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module axi_protocol_converter_v2_1_b2s_simple_fifo #
(
parameter C_WIDTH = 8,
parameter C_AWIDTH = 4,
parameter C_DEPTH = 16
)
(
input wire clk, // Main System Clock (Sync FIFO)
input wire rst, // FIFO Counter Reset (Clk
input wire wr_en, // FIFO Write Enable (Clk)
input wire rd_en, // FIFO Read Enable (Clk)
input wire [C_WIDTH-1:0] din, // FIFO Data Input (Clk)
output wire [C_WIDTH-1:0] dout, // FIFO Data Output (Clk)
output wire a_full,
output wire full, // FIFO FULL Status (Clk)
output wire a_empty,
output wire empty // FIFO EMPTY Status (Clk)
);
///////////////////////////////////////
// FIFO Local Parameters
///////////////////////////////////////
localparam [C_AWIDTH-1:0] C_EMPTY = ~(0);
localparam [C_AWIDTH-1:0] C_EMPTY_PRE = (0);
localparam [C_AWIDTH-1:0] C_FULL = C_EMPTY-1;
localparam [C_AWIDTH-1:0] C_FULL_PRE = (C_DEPTH < 8) ? C_FULL-1 : C_FULL-(C_DEPTH/8);
///////////////////////////////////////
// FIFO Internal Signals
///////////////////////////////////////
reg [C_WIDTH-1:0] memory [C_DEPTH-1:0];
reg [C_AWIDTH-1:0] cnt_read;
// synthesis attribute MAX_FANOUT of cnt_read is 10;
///////////////////////////////////////
// Main simple FIFO Array
///////////////////////////////////////
always @(posedge clk) begin : BLKSRL
integer i;
if (wr_en) begin
for (i = 0; i < C_DEPTH-1; i = i + 1) begin
memory[i+1] <= memory[i];
end
memory[0] <= din;
end
end
///////////////////////////////////////
// Read Index Counter
// Up/Down Counter
// *** Notice that there is no ***
// *** OVERRUN protection. ***
///////////////////////////////////////
always @(posedge clk) begin
if (rst) cnt_read <= C_EMPTY;
else if ( wr_en & !rd_en) cnt_read <= cnt_read + 1'b1;
else if (!wr_en & rd_en) cnt_read <= cnt_read - 1'b1;
end
///////////////////////////////////////
// Status Flags / Outputs
// These could be registered, but would
// increase logic in order to pre-decode
// FULL/EMPTY status.
///////////////////////////////////////
assign full = (cnt_read == C_FULL);
assign empty = (cnt_read == C_EMPTY);
assign a_full = ((cnt_read >= C_FULL_PRE) && (cnt_read != C_EMPTY));
assign a_empty = (cnt_read == C_EMPTY_PRE);
assign dout = (C_DEPTH == 1) ? memory[0] : memory[cnt_read];
endmodule
|
module axi_protocol_converter_v2_1_b2s_simple_fifo #
(
parameter C_WIDTH = 8,
parameter C_AWIDTH = 4,
parameter C_DEPTH = 16
)
(
input wire clk, // Main System Clock (Sync FIFO)
input wire rst, // FIFO Counter Reset (Clk
input wire wr_en, // FIFO Write Enable (Clk)
input wire rd_en, // FIFO Read Enable (Clk)
input wire [C_WIDTH-1:0] din, // FIFO Data Input (Clk)
output wire [C_WIDTH-1:0] dout, // FIFO Data Output (Clk)
output wire a_full,
output wire full, // FIFO FULL Status (Clk)
output wire a_empty,
output wire empty // FIFO EMPTY Status (Clk)
);
///////////////////////////////////////
// FIFO Local Parameters
///////////////////////////////////////
localparam [C_AWIDTH-1:0] C_EMPTY = ~(0);
localparam [C_AWIDTH-1:0] C_EMPTY_PRE = (0);
localparam [C_AWIDTH-1:0] C_FULL = C_EMPTY-1;
localparam [C_AWIDTH-1:0] C_FULL_PRE = (C_DEPTH < 8) ? C_FULL-1 : C_FULL-(C_DEPTH/8);
///////////////////////////////////////
// FIFO Internal Signals
///////////////////////////////////////
reg [C_WIDTH-1:0] memory [C_DEPTH-1:0];
reg [C_AWIDTH-1:0] cnt_read;
// synthesis attribute MAX_FANOUT of cnt_read is 10;
///////////////////////////////////////
// Main simple FIFO Array
///////////////////////////////////////
always @(posedge clk) begin : BLKSRL
integer i;
if (wr_en) begin
for (i = 0; i < C_DEPTH-1; i = i + 1) begin
memory[i+1] <= memory[i];
end
memory[0] <= din;
end
end
///////////////////////////////////////
// Read Index Counter
// Up/Down Counter
// *** Notice that there is no ***
// *** OVERRUN protection. ***
///////////////////////////////////////
always @(posedge clk) begin
if (rst) cnt_read <= C_EMPTY;
else if ( wr_en & !rd_en) cnt_read <= cnt_read + 1'b1;
else if (!wr_en & rd_en) cnt_read <= cnt_read - 1'b1;
end
///////////////////////////////////////
// Status Flags / Outputs
// These could be registered, but would
// increase logic in order to pre-decode
// FULL/EMPTY status.
///////////////////////////////////////
assign full = (cnt_read == C_FULL);
assign empty = (cnt_read == C_EMPTY);
assign a_full = ((cnt_read >= C_FULL_PRE) && (cnt_read != C_EMPTY));
assign a_empty = (cnt_read == C_EMPTY_PRE);
assign dout = (C_DEPTH == 1) ? memory[0] : memory[cnt_read];
endmodule
|
module axi_protocol_converter_v2_1_b2s_simple_fifo #
(
parameter C_WIDTH = 8,
parameter C_AWIDTH = 4,
parameter C_DEPTH = 16
)
(
input wire clk, // Main System Clock (Sync FIFO)
input wire rst, // FIFO Counter Reset (Clk
input wire wr_en, // FIFO Write Enable (Clk)
input wire rd_en, // FIFO Read Enable (Clk)
input wire [C_WIDTH-1:0] din, // FIFO Data Input (Clk)
output wire [C_WIDTH-1:0] dout, // FIFO Data Output (Clk)
output wire a_full,
output wire full, // FIFO FULL Status (Clk)
output wire a_empty,
output wire empty // FIFO EMPTY Status (Clk)
);
///////////////////////////////////////
// FIFO Local Parameters
///////////////////////////////////////
localparam [C_AWIDTH-1:0] C_EMPTY = ~(0);
localparam [C_AWIDTH-1:0] C_EMPTY_PRE = (0);
localparam [C_AWIDTH-1:0] C_FULL = C_EMPTY-1;
localparam [C_AWIDTH-1:0] C_FULL_PRE = (C_DEPTH < 8) ? C_FULL-1 : C_FULL-(C_DEPTH/8);
///////////////////////////////////////
// FIFO Internal Signals
///////////////////////////////////////
reg [C_WIDTH-1:0] memory [C_DEPTH-1:0];
reg [C_AWIDTH-1:0] cnt_read;
// synthesis attribute MAX_FANOUT of cnt_read is 10;
///////////////////////////////////////
// Main simple FIFO Array
///////////////////////////////////////
always @(posedge clk) begin : BLKSRL
integer i;
if (wr_en) begin
for (i = 0; i < C_DEPTH-1; i = i + 1) begin
memory[i+1] <= memory[i];
end
memory[0] <= din;
end
end
///////////////////////////////////////
// Read Index Counter
// Up/Down Counter
// *** Notice that there is no ***
// *** OVERRUN protection. ***
///////////////////////////////////////
always @(posedge clk) begin
if (rst) cnt_read <= C_EMPTY;
else if ( wr_en & !rd_en) cnt_read <= cnt_read + 1'b1;
else if (!wr_en & rd_en) cnt_read <= cnt_read - 1'b1;
end
///////////////////////////////////////
// Status Flags / Outputs
// These could be registered, but would
// increase logic in order to pre-decode
// FULL/EMPTY status.
///////////////////////////////////////
assign full = (cnt_read == C_FULL);
assign empty = (cnt_read == C_EMPTY);
assign a_full = ((cnt_read >= C_FULL_PRE) && (cnt_read != C_EMPTY));
assign a_empty = (cnt_read == C_EMPTY_PRE);
assign dout = (C_DEPTH == 1) ? memory[0] : memory[cnt_read];
endmodule
|
module axi_protocol_converter_v2_1_b2s_simple_fifo #
(
parameter C_WIDTH = 8,
parameter C_AWIDTH = 4,
parameter C_DEPTH = 16
)
(
input wire clk, // Main System Clock (Sync FIFO)
input wire rst, // FIFO Counter Reset (Clk
input wire wr_en, // FIFO Write Enable (Clk)
input wire rd_en, // FIFO Read Enable (Clk)
input wire [C_WIDTH-1:0] din, // FIFO Data Input (Clk)
output wire [C_WIDTH-1:0] dout, // FIFO Data Output (Clk)
output wire a_full,
output wire full, // FIFO FULL Status (Clk)
output wire a_empty,
output wire empty // FIFO EMPTY Status (Clk)
);
///////////////////////////////////////
// FIFO Local Parameters
///////////////////////////////////////
localparam [C_AWIDTH-1:0] C_EMPTY = ~(0);
localparam [C_AWIDTH-1:0] C_EMPTY_PRE = (0);
localparam [C_AWIDTH-1:0] C_FULL = C_EMPTY-1;
localparam [C_AWIDTH-1:0] C_FULL_PRE = (C_DEPTH < 8) ? C_FULL-1 : C_FULL-(C_DEPTH/8);
///////////////////////////////////////
// FIFO Internal Signals
///////////////////////////////////////
reg [C_WIDTH-1:0] memory [C_DEPTH-1:0];
reg [C_AWIDTH-1:0] cnt_read;
// synthesis attribute MAX_FANOUT of cnt_read is 10;
///////////////////////////////////////
// Main simple FIFO Array
///////////////////////////////////////
always @(posedge clk) begin : BLKSRL
integer i;
if (wr_en) begin
for (i = 0; i < C_DEPTH-1; i = i + 1) begin
memory[i+1] <= memory[i];
end
memory[0] <= din;
end
end
///////////////////////////////////////
// Read Index Counter
// Up/Down Counter
// *** Notice that there is no ***
// *** OVERRUN protection. ***
///////////////////////////////////////
always @(posedge clk) begin
if (rst) cnt_read <= C_EMPTY;
else if ( wr_en & !rd_en) cnt_read <= cnt_read + 1'b1;
else if (!wr_en & rd_en) cnt_read <= cnt_read - 1'b1;
end
///////////////////////////////////////
// Status Flags / Outputs
// These could be registered, but would
// increase logic in order to pre-decode
// FULL/EMPTY status.
///////////////////////////////////////
assign full = (cnt_read == C_FULL);
assign empty = (cnt_read == C_EMPTY);
assign a_full = ((cnt_read >= C_FULL_PRE) && (cnt_read != C_EMPTY));
assign a_empty = (cnt_read == C_EMPTY_PRE);
assign dout = (C_DEPTH == 1) ? memory[0] : memory[cnt_read];
endmodule
|
module sha256_transform #(
parameter LOOP = 7'd64 // For ltcminer
) (
input clk,
input feedback,
input [5:0] cnt,
input [255:0] rx_state,
input [511:0] rx_input,
output reg [255:0] tx_hash
);
// Constants defined by the SHA-2 standard.
localparam Ks = {
32'h428a2f98, 32'h71374491, 32'hb5c0fbcf, 32'he9b5dba5,
32'h3956c25b, 32'h59f111f1, 32'h923f82a4, 32'hab1c5ed5,
32'hd807aa98, 32'h12835b01, 32'h243185be, 32'h550c7dc3,
32'h72be5d74, 32'h80deb1fe, 32'h9bdc06a7, 32'hc19bf174,
32'he49b69c1, 32'hefbe4786, 32'h0fc19dc6, 32'h240ca1cc,
32'h2de92c6f, 32'h4a7484aa, 32'h5cb0a9dc, 32'h76f988da,
32'h983e5152, 32'ha831c66d, 32'hb00327c8, 32'hbf597fc7,
32'hc6e00bf3, 32'hd5a79147, 32'h06ca6351, 32'h14292967,
32'h27b70a85, 32'h2e1b2138, 32'h4d2c6dfc, 32'h53380d13,
32'h650a7354, 32'h766a0abb, 32'h81c2c92e, 32'h92722c85,
32'ha2bfe8a1, 32'ha81a664b, 32'hc24b8b70, 32'hc76c51a3,
32'hd192e819, 32'hd6990624, 32'hf40e3585, 32'h106aa070,
32'h19a4c116, 32'h1e376c08, 32'h2748774c, 32'h34b0bcb5,
32'h391c0cb3, 32'h4ed8aa4a, 32'h5b9cca4f, 32'h682e6ff3,
32'h748f82ee, 32'h78a5636f, 32'h84c87814, 32'h8cc70208,
32'h90befffa, 32'ha4506ceb, 32'hbef9a3f7, 32'hc67178f2};
genvar i;
generate
for (i = 0; i < 64/LOOP; i = i + 1) begin : HASHERS
// These are declared as registers in sha256_digester
wire [511:0] W; // reg tx_w
wire [255:0] state; // reg tx_state
if(i == 0)
sha256_digester U (
.clk(clk),
.k(Ks[32*(63-cnt) +: 32]),
.rx_w(feedback ? W : rx_input),
.rx_state(feedback ? state : rx_state),
.tx_w(W),
.tx_state(state)
);
else
sha256_digester U (
.clk(clk),
.k(Ks[32*(63-LOOP*i-cnt) +: 32]),
.rx_w(feedback ? W : HASHERS[i-1].W),
.rx_state(feedback ? state : HASHERS[i-1].state),
.tx_w(W),
.tx_state(state)
);
end
endgenerate
always @ (posedge clk)
begin
if (!feedback)
begin
tx_hash[`IDX(0)] <= rx_state[`IDX(0)] + HASHERS[64/LOOP-6'd1].state[`IDX(0)];
tx_hash[`IDX(1)] <= rx_state[`IDX(1)] + HASHERS[64/LOOP-6'd1].state[`IDX(1)];
tx_hash[`IDX(2)] <= rx_state[`IDX(2)] + HASHERS[64/LOOP-6'd1].state[`IDX(2)];
tx_hash[`IDX(3)] <= rx_state[`IDX(3)] + HASHERS[64/LOOP-6'd1].state[`IDX(3)];
tx_hash[`IDX(4)] <= rx_state[`IDX(4)] + HASHERS[64/LOOP-6'd1].state[`IDX(4)];
tx_hash[`IDX(5)] <= rx_state[`IDX(5)] + HASHERS[64/LOOP-6'd1].state[`IDX(5)];
tx_hash[`IDX(6)] <= rx_state[`IDX(6)] + HASHERS[64/LOOP-6'd1].state[`IDX(6)];
tx_hash[`IDX(7)] <= rx_state[`IDX(7)] + HASHERS[64/LOOP-6'd1].state[`IDX(7)];
end
end
endmodule
|
module sha256_digester (clk, k, rx_w, rx_state, tx_w, tx_state);
input clk;
input [31:0] k;
input [511:0] rx_w;
input [255:0] rx_state;
output reg [511:0] tx_w;
output reg [255:0] tx_state;
wire [31:0] e0_w, e1_w, ch_w, maj_w, s0_w, s1_w;
e0 e0_blk (rx_state[`IDX(0)], e0_w);
e1 e1_blk (rx_state[`IDX(4)], e1_w);
ch ch_blk (rx_state[`IDX(4)], rx_state[`IDX(5)], rx_state[`IDX(6)], ch_w);
maj maj_blk (rx_state[`IDX(0)], rx_state[`IDX(1)], rx_state[`IDX(2)], maj_w);
s0 s0_blk (rx_w[63:32], s0_w);
s1 s1_blk (rx_w[479:448], s1_w);
wire [31:0] t1 = rx_state[`IDX(7)] + e1_w + ch_w + rx_w[31:0] + k;
wire [31:0] t2 = e0_w + maj_w;
wire [31:0] new_w = s1_w + rx_w[319:288] + s0_w + rx_w[31:0];
always @ (posedge clk)
begin
tx_w[511:480] <= new_w;
tx_w[479:0] <= rx_w[511:32];
tx_state[`IDX(7)] <= rx_state[`IDX(6)];
tx_state[`IDX(6)] <= rx_state[`IDX(5)];
tx_state[`IDX(5)] <= rx_state[`IDX(4)];
tx_state[`IDX(4)] <= rx_state[`IDX(3)] + t1;
tx_state[`IDX(3)] <= rx_state[`IDX(2)];
tx_state[`IDX(2)] <= rx_state[`IDX(1)];
tx_state[`IDX(1)] <= rx_state[`IDX(0)];
tx_state[`IDX(0)] <= t1 + t2;
end
endmodule
|
module sha256_transform #(
parameter LOOP = 7'd64 // For ltcminer
) (
input clk,
input feedback,
input [5:0] cnt,
input [255:0] rx_state,
input [511:0] rx_input,
output reg [255:0] tx_hash
);
// Constants defined by the SHA-2 standard.
localparam Ks = {
32'h428a2f98, 32'h71374491, 32'hb5c0fbcf, 32'he9b5dba5,
32'h3956c25b, 32'h59f111f1, 32'h923f82a4, 32'hab1c5ed5,
32'hd807aa98, 32'h12835b01, 32'h243185be, 32'h550c7dc3,
32'h72be5d74, 32'h80deb1fe, 32'h9bdc06a7, 32'hc19bf174,
32'he49b69c1, 32'hefbe4786, 32'h0fc19dc6, 32'h240ca1cc,
32'h2de92c6f, 32'h4a7484aa, 32'h5cb0a9dc, 32'h76f988da,
32'h983e5152, 32'ha831c66d, 32'hb00327c8, 32'hbf597fc7,
32'hc6e00bf3, 32'hd5a79147, 32'h06ca6351, 32'h14292967,
32'h27b70a85, 32'h2e1b2138, 32'h4d2c6dfc, 32'h53380d13,
32'h650a7354, 32'h766a0abb, 32'h81c2c92e, 32'h92722c85,
32'ha2bfe8a1, 32'ha81a664b, 32'hc24b8b70, 32'hc76c51a3,
32'hd192e819, 32'hd6990624, 32'hf40e3585, 32'h106aa070,
32'h19a4c116, 32'h1e376c08, 32'h2748774c, 32'h34b0bcb5,
32'h391c0cb3, 32'h4ed8aa4a, 32'h5b9cca4f, 32'h682e6ff3,
32'h748f82ee, 32'h78a5636f, 32'h84c87814, 32'h8cc70208,
32'h90befffa, 32'ha4506ceb, 32'hbef9a3f7, 32'hc67178f2};
genvar i;
generate
for (i = 0; i < 64/LOOP; i = i + 1) begin : HASHERS
// These are declared as registers in sha256_digester
wire [511:0] W; // reg tx_w
wire [255:0] state; // reg tx_state
if(i == 0)
sha256_digester U (
.clk(clk),
.k(Ks[32*(63-cnt) +: 32]),
.rx_w(feedback ? W : rx_input),
.rx_state(feedback ? state : rx_state),
.tx_w(W),
.tx_state(state)
);
else
sha256_digester U (
.clk(clk),
.k(Ks[32*(63-LOOP*i-cnt) +: 32]),
.rx_w(feedback ? W : HASHERS[i-1].W),
.rx_state(feedback ? state : HASHERS[i-1].state),
.tx_w(W),
.tx_state(state)
);
end
endgenerate
always @ (posedge clk)
begin
if (!feedback)
begin
tx_hash[`IDX(0)] <= rx_state[`IDX(0)] + HASHERS[64/LOOP-6'd1].state[`IDX(0)];
tx_hash[`IDX(1)] <= rx_state[`IDX(1)] + HASHERS[64/LOOP-6'd1].state[`IDX(1)];
tx_hash[`IDX(2)] <= rx_state[`IDX(2)] + HASHERS[64/LOOP-6'd1].state[`IDX(2)];
tx_hash[`IDX(3)] <= rx_state[`IDX(3)] + HASHERS[64/LOOP-6'd1].state[`IDX(3)];
tx_hash[`IDX(4)] <= rx_state[`IDX(4)] + HASHERS[64/LOOP-6'd1].state[`IDX(4)];
tx_hash[`IDX(5)] <= rx_state[`IDX(5)] + HASHERS[64/LOOP-6'd1].state[`IDX(5)];
tx_hash[`IDX(6)] <= rx_state[`IDX(6)] + HASHERS[64/LOOP-6'd1].state[`IDX(6)];
tx_hash[`IDX(7)] <= rx_state[`IDX(7)] + HASHERS[64/LOOP-6'd1].state[`IDX(7)];
end
end
endmodule
|
module sha256_digester (clk, k, rx_w, rx_state, tx_w, tx_state);
input clk;
input [31:0] k;
input [511:0] rx_w;
input [255:0] rx_state;
output reg [511:0] tx_w;
output reg [255:0] tx_state;
wire [31:0] e0_w, e1_w, ch_w, maj_w, s0_w, s1_w;
e0 e0_blk (rx_state[`IDX(0)], e0_w);
e1 e1_blk (rx_state[`IDX(4)], e1_w);
ch ch_blk (rx_state[`IDX(4)], rx_state[`IDX(5)], rx_state[`IDX(6)], ch_w);
maj maj_blk (rx_state[`IDX(0)], rx_state[`IDX(1)], rx_state[`IDX(2)], maj_w);
s0 s0_blk (rx_w[63:32], s0_w);
s1 s1_blk (rx_w[479:448], s1_w);
wire [31:0] t1 = rx_state[`IDX(7)] + e1_w + ch_w + rx_w[31:0] + k;
wire [31:0] t2 = e0_w + maj_w;
wire [31:0] new_w = s1_w + rx_w[319:288] + s0_w + rx_w[31:0];
always @ (posedge clk)
begin
tx_w[511:480] <= new_w;
tx_w[479:0] <= rx_w[511:32];
tx_state[`IDX(7)] <= rx_state[`IDX(6)];
tx_state[`IDX(6)] <= rx_state[`IDX(5)];
tx_state[`IDX(5)] <= rx_state[`IDX(4)];
tx_state[`IDX(4)] <= rx_state[`IDX(3)] + t1;
tx_state[`IDX(3)] <= rx_state[`IDX(2)];
tx_state[`IDX(2)] <= rx_state[`IDX(1)];
tx_state[`IDX(1)] <= rx_state[`IDX(0)];
tx_state[`IDX(0)] <= t1 + t2;
end
endmodule
|
module sha256_transform #(
parameter LOOP = 7'd64 // For ltcminer
) (
input clk,
input feedback,
input [5:0] cnt,
input [255:0] rx_state,
input [511:0] rx_input,
output reg [255:0] tx_hash
);
// Constants defined by the SHA-2 standard.
localparam Ks = {
32'h428a2f98, 32'h71374491, 32'hb5c0fbcf, 32'he9b5dba5,
32'h3956c25b, 32'h59f111f1, 32'h923f82a4, 32'hab1c5ed5,
32'hd807aa98, 32'h12835b01, 32'h243185be, 32'h550c7dc3,
32'h72be5d74, 32'h80deb1fe, 32'h9bdc06a7, 32'hc19bf174,
32'he49b69c1, 32'hefbe4786, 32'h0fc19dc6, 32'h240ca1cc,
32'h2de92c6f, 32'h4a7484aa, 32'h5cb0a9dc, 32'h76f988da,
32'h983e5152, 32'ha831c66d, 32'hb00327c8, 32'hbf597fc7,
32'hc6e00bf3, 32'hd5a79147, 32'h06ca6351, 32'h14292967,
32'h27b70a85, 32'h2e1b2138, 32'h4d2c6dfc, 32'h53380d13,
32'h650a7354, 32'h766a0abb, 32'h81c2c92e, 32'h92722c85,
32'ha2bfe8a1, 32'ha81a664b, 32'hc24b8b70, 32'hc76c51a3,
32'hd192e819, 32'hd6990624, 32'hf40e3585, 32'h106aa070,
32'h19a4c116, 32'h1e376c08, 32'h2748774c, 32'h34b0bcb5,
32'h391c0cb3, 32'h4ed8aa4a, 32'h5b9cca4f, 32'h682e6ff3,
32'h748f82ee, 32'h78a5636f, 32'h84c87814, 32'h8cc70208,
32'h90befffa, 32'ha4506ceb, 32'hbef9a3f7, 32'hc67178f2};
genvar i;
generate
for (i = 0; i < 64/LOOP; i = i + 1) begin : HASHERS
// These are declared as registers in sha256_digester
wire [511:0] W; // reg tx_w
wire [255:0] state; // reg tx_state
if(i == 0)
sha256_digester U (
.clk(clk),
.k(Ks[32*(63-cnt) +: 32]),
.rx_w(feedback ? W : rx_input),
.rx_state(feedback ? state : rx_state),
.tx_w(W),
.tx_state(state)
);
else
sha256_digester U (
.clk(clk),
.k(Ks[32*(63-LOOP*i-cnt) +: 32]),
.rx_w(feedback ? W : HASHERS[i-1].W),
.rx_state(feedback ? state : HASHERS[i-1].state),
.tx_w(W),
.tx_state(state)
);
end
endgenerate
always @ (posedge clk)
begin
if (!feedback)
begin
tx_hash[`IDX(0)] <= rx_state[`IDX(0)] + HASHERS[64/LOOP-6'd1].state[`IDX(0)];
tx_hash[`IDX(1)] <= rx_state[`IDX(1)] + HASHERS[64/LOOP-6'd1].state[`IDX(1)];
tx_hash[`IDX(2)] <= rx_state[`IDX(2)] + HASHERS[64/LOOP-6'd1].state[`IDX(2)];
tx_hash[`IDX(3)] <= rx_state[`IDX(3)] + HASHERS[64/LOOP-6'd1].state[`IDX(3)];
tx_hash[`IDX(4)] <= rx_state[`IDX(4)] + HASHERS[64/LOOP-6'd1].state[`IDX(4)];
tx_hash[`IDX(5)] <= rx_state[`IDX(5)] + HASHERS[64/LOOP-6'd1].state[`IDX(5)];
tx_hash[`IDX(6)] <= rx_state[`IDX(6)] + HASHERS[64/LOOP-6'd1].state[`IDX(6)];
tx_hash[`IDX(7)] <= rx_state[`IDX(7)] + HASHERS[64/LOOP-6'd1].state[`IDX(7)];
end
end
endmodule
|
module sha256_digester (clk, k, rx_w, rx_state, tx_w, tx_state);
input clk;
input [31:0] k;
input [511:0] rx_w;
input [255:0] rx_state;
output reg [511:0] tx_w;
output reg [255:0] tx_state;
wire [31:0] e0_w, e1_w, ch_w, maj_w, s0_w, s1_w;
e0 e0_blk (rx_state[`IDX(0)], e0_w);
e1 e1_blk (rx_state[`IDX(4)], e1_w);
ch ch_blk (rx_state[`IDX(4)], rx_state[`IDX(5)], rx_state[`IDX(6)], ch_w);
maj maj_blk (rx_state[`IDX(0)], rx_state[`IDX(1)], rx_state[`IDX(2)], maj_w);
s0 s0_blk (rx_w[63:32], s0_w);
s1 s1_blk (rx_w[479:448], s1_w);
wire [31:0] t1 = rx_state[`IDX(7)] + e1_w + ch_w + rx_w[31:0] + k;
wire [31:0] t2 = e0_w + maj_w;
wire [31:0] new_w = s1_w + rx_w[319:288] + s0_w + rx_w[31:0];
always @ (posedge clk)
begin
tx_w[511:480] <= new_w;
tx_w[479:0] <= rx_w[511:32];
tx_state[`IDX(7)] <= rx_state[`IDX(6)];
tx_state[`IDX(6)] <= rx_state[`IDX(5)];
tx_state[`IDX(5)] <= rx_state[`IDX(4)];
tx_state[`IDX(4)] <= rx_state[`IDX(3)] + t1;
tx_state[`IDX(3)] <= rx_state[`IDX(2)];
tx_state[`IDX(2)] <= rx_state[`IDX(1)];
tx_state[`IDX(1)] <= rx_state[`IDX(0)];
tx_state[`IDX(0)] <= t1 + t2;
end
endmodule
|
module testbed_hi_simulate;
reg pck0;
reg [7:0] adc_d;
reg mod_type;
wire pwr_lo;
wire adc_clk;
reg ck_1356meg;
reg ck_1356megb;
wire ssp_frame;
wire ssp_din;
wire ssp_clk;
reg ssp_dout;
wire pwr_hi;
wire pwr_oe1;
wire pwr_oe2;
wire pwr_oe3;
wire pwr_oe4;
wire cross_lo;
wire cross_hi;
wire dbg;
hi_simulate #(5,200) dut(
.pck0(pck0),
.ck_1356meg(ck_1356meg),
.ck_1356megb(ck_1356megb),
.pwr_lo(pwr_lo),
.pwr_hi(pwr_hi),
.pwr_oe1(pwr_oe1),
.pwr_oe2(pwr_oe2),
.pwr_oe3(pwr_oe3),
.pwr_oe4(pwr_oe4),
.adc_d(adc_d),
.adc_clk(adc_clk),
.ssp_frame(ssp_frame),
.ssp_din(ssp_din),
.ssp_dout(ssp_dout),
.ssp_clk(ssp_clk),
.cross_hi(cross_hi),
.cross_lo(cross_lo),
.dbg(dbg),
.mod_type(mod_type)
);
integer idx, i;
// main clock
always #5 begin
ck_1356megb = !ck_1356megb;
ck_1356meg = ck_1356megb;
end
always begin
@(negedge adc_clk) ;
adc_d = $random;
end
//crank DUT
task crank_dut;
begin
@(negedge ssp_clk) ;
ssp_dout = $random;
end
endtask
initial begin
// init inputs
ck_1356megb = 0;
// random values
adc_d = 0;
ssp_dout=1;
// shallow modulation off
mod_type=0;
for (i = 0 ; i < 16 ; i = i + 1) begin
crank_dut;
end
// shallow modulation on
mod_type=1;
for (i = 0 ; i < 16 ; i = i + 1) begin
crank_dut;
end
$finish;
end
endmodule
|
module processing_system7_v5_5_atc #
(
parameter C_FAMILY = "rtl",
// FPGA Family. Current version: virtex6, spartan6 or later.
parameter integer C_AXI_ID_WIDTH = 4,
// Width of all ID signals on SI and MI side of checker.
// Range: >= 1.
parameter integer C_AXI_ADDR_WIDTH = 32,
// Width of all ADDR signals on SI and MI side of checker.
// Range: 32.
parameter integer C_AXI_DATA_WIDTH = 64,
// Width of all DATA signals on SI and MI side of checker.
// Range: 64.
parameter integer C_AXI_AWUSER_WIDTH = 1,
// Width of AWUSER signals.
// Range: >= 1.
parameter integer C_AXI_ARUSER_WIDTH = 1,
// Width of ARUSER signals.
// Range: >= 1.
parameter integer C_AXI_WUSER_WIDTH = 1,
// Width of WUSER signals.
// Range: >= 1.
parameter integer C_AXI_RUSER_WIDTH = 1,
// Width of RUSER signals.
// Range: >= 1.
parameter integer C_AXI_BUSER_WIDTH = 1
// Width of BUSER signals.
// Range: >= 1.
)
(
// Global Signals
input wire ACLK,
input wire ARESETN,
// Slave Interface Write Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_AWID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_AWADDR,
input wire [4-1:0] S_AXI_AWLEN,
input wire [3-1:0] S_AXI_AWSIZE,
input wire [2-1:0] S_AXI_AWBURST,
input wire [2-1:0] S_AXI_AWLOCK,
input wire [4-1:0] S_AXI_AWCACHE,
input wire [3-1:0] S_AXI_AWPROT,
input wire [C_AXI_AWUSER_WIDTH-1:0] S_AXI_AWUSER,
input wire S_AXI_AWVALID,
output wire S_AXI_AWREADY,
// Slave Interface Write Data Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_WID,
input wire [C_AXI_DATA_WIDTH-1:0] S_AXI_WDATA,
input wire [C_AXI_DATA_WIDTH/8-1:0] S_AXI_WSTRB,
input wire S_AXI_WLAST,
input wire [C_AXI_WUSER_WIDTH-1:0] S_AXI_WUSER,
input wire S_AXI_WVALID,
output wire S_AXI_WREADY,
// Slave Interface Write Response Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_BID,
output wire [2-1:0] S_AXI_BRESP,
output wire [C_AXI_BUSER_WIDTH-1:0] S_AXI_BUSER,
output wire S_AXI_BVALID,
input wire S_AXI_BREADY,
// Slave Interface Read Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_ARID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_ARADDR,
input wire [4-1:0] S_AXI_ARLEN,
input wire [3-1:0] S_AXI_ARSIZE,
input wire [2-1:0] S_AXI_ARBURST,
input wire [2-1:0] S_AXI_ARLOCK,
input wire [4-1:0] S_AXI_ARCACHE,
input wire [3-1:0] S_AXI_ARPROT,
input wire [C_AXI_ARUSER_WIDTH-1:0] S_AXI_ARUSER,
input wire S_AXI_ARVALID,
output wire S_AXI_ARREADY,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Write Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_AWID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_AWADDR,
output wire [4-1:0] M_AXI_AWLEN,
output wire [3-1:0] M_AXI_AWSIZE,
output wire [2-1:0] M_AXI_AWBURST,
output wire [2-1:0] M_AXI_AWLOCK,
output wire [4-1:0] M_AXI_AWCACHE,
output wire [3-1:0] M_AXI_AWPROT,
output wire [C_AXI_AWUSER_WIDTH-1:0] M_AXI_AWUSER,
output wire M_AXI_AWVALID,
input wire M_AXI_AWREADY,
// Master Interface Write Data Ports
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_WID,
output wire [C_AXI_DATA_WIDTH-1:0] M_AXI_WDATA,
output wire [C_AXI_DATA_WIDTH/8-1:0] M_AXI_WSTRB,
output wire M_AXI_WLAST,
output wire [C_AXI_WUSER_WIDTH-1:0] M_AXI_WUSER,
output wire M_AXI_WVALID,
input wire M_AXI_WREADY,
// Master Interface Write Response Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_BID,
input wire [2-1:0] M_AXI_BRESP,
input wire [C_AXI_BUSER_WIDTH-1:0] M_AXI_BUSER,
input wire M_AXI_BVALID,
output wire M_AXI_BREADY,
// Master Interface Read Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_ARID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_ARADDR,
output wire [4-1:0] M_AXI_ARLEN,
output wire [3-1:0] M_AXI_ARSIZE,
output wire [2-1:0] M_AXI_ARBURST,
output wire [2-1:0] M_AXI_ARLOCK,
output wire [4-1:0] M_AXI_ARCACHE,
output wire [3-1:0] M_AXI_ARPROT,
output wire [C_AXI_ARUSER_WIDTH-1:0] M_AXI_ARUSER,
output wire M_AXI_ARVALID,
input wire M_AXI_ARREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY,
output wire ERROR_TRIGGER,
output wire [C_AXI_ID_WIDTH-1:0] ERROR_TRANSACTION_ID
);
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
localparam C_FIFO_DEPTH_LOG = 4;
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Internal reset.
reg ARESET;
// AW->W command queue signals.
wire cmd_w_valid;
wire cmd_w_check;
wire [C_AXI_ID_WIDTH-1:0] cmd_w_id;
wire cmd_w_ready;
// W->B command queue signals.
wire cmd_b_push;
wire cmd_b_error;
wire [C_AXI_ID_WIDTH-1:0] cmd_b_id;
wire cmd_b_full;
wire [C_FIFO_DEPTH_LOG-1:0] cmd_b_addr;
wire cmd_b_ready;
/////////////////////////////////////////////////////////////////////////////
// Handle Internal Reset
/////////////////////////////////////////////////////////////////////////////
always @ (posedge ACLK) begin
ARESET <= !ARESETN;
end
/////////////////////////////////////////////////////////////////////////////
// Handle Write Channels (AW/W/B)
/////////////////////////////////////////////////////////////////////////////
// Write Address Channel.
processing_system7_v5_5_aw_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_ADDR_WIDTH (C_AXI_ADDR_WIDTH),
.C_AXI_AWUSER_WIDTH (C_AXI_AWUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_addr_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (Out)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Address Ports
.S_AXI_AWID (S_AXI_AWID),
.S_AXI_AWADDR (S_AXI_AWADDR),
.S_AXI_AWLEN (S_AXI_AWLEN),
.S_AXI_AWSIZE (S_AXI_AWSIZE),
.S_AXI_AWBURST (S_AXI_AWBURST),
.S_AXI_AWLOCK (S_AXI_AWLOCK),
.S_AXI_AWCACHE (S_AXI_AWCACHE),
.S_AXI_AWPROT (S_AXI_AWPROT),
.S_AXI_AWUSER (S_AXI_AWUSER),
.S_AXI_AWVALID (S_AXI_AWVALID),
.S_AXI_AWREADY (S_AXI_AWREADY),
// Master Interface Write Address Port
.M_AXI_AWID (M_AXI_AWID),
.M_AXI_AWADDR (M_AXI_AWADDR),
.M_AXI_AWLEN (M_AXI_AWLEN),
.M_AXI_AWSIZE (M_AXI_AWSIZE),
.M_AXI_AWBURST (M_AXI_AWBURST),
.M_AXI_AWLOCK (M_AXI_AWLOCK),
.M_AXI_AWCACHE (M_AXI_AWCACHE),
.M_AXI_AWPROT (M_AXI_AWPROT),
.M_AXI_AWUSER (M_AXI_AWUSER),
.M_AXI_AWVALID (M_AXI_AWVALID),
.M_AXI_AWREADY (M_AXI_AWREADY)
);
// Write Data channel.
processing_system7_v5_5_w_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_DATA_WIDTH (C_AXI_DATA_WIDTH),
.C_AXI_WUSER_WIDTH (C_AXI_WUSER_WIDTH)
) write_data_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
// Command Interface (Out)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
// Slave Interface Write Data Ports
.S_AXI_WID (S_AXI_WID),
.S_AXI_WDATA (S_AXI_WDATA),
.S_AXI_WSTRB (S_AXI_WSTRB),
.S_AXI_WLAST (S_AXI_WLAST),
.S_AXI_WUSER (S_AXI_WUSER),
.S_AXI_WVALID (S_AXI_WVALID),
.S_AXI_WREADY (S_AXI_WREADY),
// Master Interface Write Data Ports
.M_AXI_WID (M_AXI_WID),
.M_AXI_WDATA (M_AXI_WDATA),
.M_AXI_WSTRB (M_AXI_WSTRB),
.M_AXI_WLAST (M_AXI_WLAST),
.M_AXI_WUSER (M_AXI_WUSER),
.M_AXI_WVALID (M_AXI_WVALID),
.M_AXI_WREADY (M_AXI_WREADY)
);
// Write Response channel.
processing_system7_v5_5_b_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_BUSER_WIDTH (C_AXI_BUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_response_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Response Ports
.S_AXI_BID (S_AXI_BID),
.S_AXI_BRESP (S_AXI_BRESP),
.S_AXI_BUSER (S_AXI_BUSER),
.S_AXI_BVALID (S_AXI_BVALID),
.S_AXI_BREADY (S_AXI_BREADY),
// Master Interface Write Response Ports
.M_AXI_BID (M_AXI_BID),
.M_AXI_BRESP (M_AXI_BRESP),
.M_AXI_BUSER (M_AXI_BUSER),
.M_AXI_BVALID (M_AXI_BVALID),
.M_AXI_BREADY (M_AXI_BREADY),
// Trigger detection
.ERROR_TRIGGER (ERROR_TRIGGER),
.ERROR_TRANSACTION_ID (ERROR_TRANSACTION_ID)
);
/////////////////////////////////////////////////////////////////////////////
// Handle Read Channels (AR/R)
/////////////////////////////////////////////////////////////////////////////
// Read Address Port
assign M_AXI_ARID = S_AXI_ARID;
assign M_AXI_ARADDR = S_AXI_ARADDR;
assign M_AXI_ARLEN = S_AXI_ARLEN;
assign M_AXI_ARSIZE = S_AXI_ARSIZE;
assign M_AXI_ARBURST = S_AXI_ARBURST;
assign M_AXI_ARLOCK = S_AXI_ARLOCK;
assign M_AXI_ARCACHE = S_AXI_ARCACHE;
assign M_AXI_ARPROT = S_AXI_ARPROT;
assign M_AXI_ARUSER = S_AXI_ARUSER;
assign M_AXI_ARVALID = S_AXI_ARVALID;
assign S_AXI_ARREADY = M_AXI_ARREADY;
// Read Data Port
assign S_AXI_RID = M_AXI_RID;
assign S_AXI_RDATA = M_AXI_RDATA;
assign S_AXI_RRESP = M_AXI_RRESP;
assign S_AXI_RLAST = M_AXI_RLAST;
assign S_AXI_RUSER = M_AXI_RUSER;
assign S_AXI_RVALID = M_AXI_RVALID;
assign M_AXI_RREADY = S_AXI_RREADY;
endmodule
|
module processing_system7_v5_5_atc #
(
parameter C_FAMILY = "rtl",
// FPGA Family. Current version: virtex6, spartan6 or later.
parameter integer C_AXI_ID_WIDTH = 4,
// Width of all ID signals on SI and MI side of checker.
// Range: >= 1.
parameter integer C_AXI_ADDR_WIDTH = 32,
// Width of all ADDR signals on SI and MI side of checker.
// Range: 32.
parameter integer C_AXI_DATA_WIDTH = 64,
// Width of all DATA signals on SI and MI side of checker.
// Range: 64.
parameter integer C_AXI_AWUSER_WIDTH = 1,
// Width of AWUSER signals.
// Range: >= 1.
parameter integer C_AXI_ARUSER_WIDTH = 1,
// Width of ARUSER signals.
// Range: >= 1.
parameter integer C_AXI_WUSER_WIDTH = 1,
// Width of WUSER signals.
// Range: >= 1.
parameter integer C_AXI_RUSER_WIDTH = 1,
// Width of RUSER signals.
// Range: >= 1.
parameter integer C_AXI_BUSER_WIDTH = 1
// Width of BUSER signals.
// Range: >= 1.
)
(
// Global Signals
input wire ACLK,
input wire ARESETN,
// Slave Interface Write Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_AWID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_AWADDR,
input wire [4-1:0] S_AXI_AWLEN,
input wire [3-1:0] S_AXI_AWSIZE,
input wire [2-1:0] S_AXI_AWBURST,
input wire [2-1:0] S_AXI_AWLOCK,
input wire [4-1:0] S_AXI_AWCACHE,
input wire [3-1:0] S_AXI_AWPROT,
input wire [C_AXI_AWUSER_WIDTH-1:0] S_AXI_AWUSER,
input wire S_AXI_AWVALID,
output wire S_AXI_AWREADY,
// Slave Interface Write Data Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_WID,
input wire [C_AXI_DATA_WIDTH-1:0] S_AXI_WDATA,
input wire [C_AXI_DATA_WIDTH/8-1:0] S_AXI_WSTRB,
input wire S_AXI_WLAST,
input wire [C_AXI_WUSER_WIDTH-1:0] S_AXI_WUSER,
input wire S_AXI_WVALID,
output wire S_AXI_WREADY,
// Slave Interface Write Response Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_BID,
output wire [2-1:0] S_AXI_BRESP,
output wire [C_AXI_BUSER_WIDTH-1:0] S_AXI_BUSER,
output wire S_AXI_BVALID,
input wire S_AXI_BREADY,
// Slave Interface Read Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_ARID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_ARADDR,
input wire [4-1:0] S_AXI_ARLEN,
input wire [3-1:0] S_AXI_ARSIZE,
input wire [2-1:0] S_AXI_ARBURST,
input wire [2-1:0] S_AXI_ARLOCK,
input wire [4-1:0] S_AXI_ARCACHE,
input wire [3-1:0] S_AXI_ARPROT,
input wire [C_AXI_ARUSER_WIDTH-1:0] S_AXI_ARUSER,
input wire S_AXI_ARVALID,
output wire S_AXI_ARREADY,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Write Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_AWID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_AWADDR,
output wire [4-1:0] M_AXI_AWLEN,
output wire [3-1:0] M_AXI_AWSIZE,
output wire [2-1:0] M_AXI_AWBURST,
output wire [2-1:0] M_AXI_AWLOCK,
output wire [4-1:0] M_AXI_AWCACHE,
output wire [3-1:0] M_AXI_AWPROT,
output wire [C_AXI_AWUSER_WIDTH-1:0] M_AXI_AWUSER,
output wire M_AXI_AWVALID,
input wire M_AXI_AWREADY,
// Master Interface Write Data Ports
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_WID,
output wire [C_AXI_DATA_WIDTH-1:0] M_AXI_WDATA,
output wire [C_AXI_DATA_WIDTH/8-1:0] M_AXI_WSTRB,
output wire M_AXI_WLAST,
output wire [C_AXI_WUSER_WIDTH-1:0] M_AXI_WUSER,
output wire M_AXI_WVALID,
input wire M_AXI_WREADY,
// Master Interface Write Response Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_BID,
input wire [2-1:0] M_AXI_BRESP,
input wire [C_AXI_BUSER_WIDTH-1:0] M_AXI_BUSER,
input wire M_AXI_BVALID,
output wire M_AXI_BREADY,
// Master Interface Read Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_ARID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_ARADDR,
output wire [4-1:0] M_AXI_ARLEN,
output wire [3-1:0] M_AXI_ARSIZE,
output wire [2-1:0] M_AXI_ARBURST,
output wire [2-1:0] M_AXI_ARLOCK,
output wire [4-1:0] M_AXI_ARCACHE,
output wire [3-1:0] M_AXI_ARPROT,
output wire [C_AXI_ARUSER_WIDTH-1:0] M_AXI_ARUSER,
output wire M_AXI_ARVALID,
input wire M_AXI_ARREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY,
output wire ERROR_TRIGGER,
output wire [C_AXI_ID_WIDTH-1:0] ERROR_TRANSACTION_ID
);
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
localparam C_FIFO_DEPTH_LOG = 4;
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Internal reset.
reg ARESET;
// AW->W command queue signals.
wire cmd_w_valid;
wire cmd_w_check;
wire [C_AXI_ID_WIDTH-1:0] cmd_w_id;
wire cmd_w_ready;
// W->B command queue signals.
wire cmd_b_push;
wire cmd_b_error;
wire [C_AXI_ID_WIDTH-1:0] cmd_b_id;
wire cmd_b_full;
wire [C_FIFO_DEPTH_LOG-1:0] cmd_b_addr;
wire cmd_b_ready;
/////////////////////////////////////////////////////////////////////////////
// Handle Internal Reset
/////////////////////////////////////////////////////////////////////////////
always @ (posedge ACLK) begin
ARESET <= !ARESETN;
end
/////////////////////////////////////////////////////////////////////////////
// Handle Write Channels (AW/W/B)
/////////////////////////////////////////////////////////////////////////////
// Write Address Channel.
processing_system7_v5_5_aw_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_ADDR_WIDTH (C_AXI_ADDR_WIDTH),
.C_AXI_AWUSER_WIDTH (C_AXI_AWUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_addr_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (Out)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Address Ports
.S_AXI_AWID (S_AXI_AWID),
.S_AXI_AWADDR (S_AXI_AWADDR),
.S_AXI_AWLEN (S_AXI_AWLEN),
.S_AXI_AWSIZE (S_AXI_AWSIZE),
.S_AXI_AWBURST (S_AXI_AWBURST),
.S_AXI_AWLOCK (S_AXI_AWLOCK),
.S_AXI_AWCACHE (S_AXI_AWCACHE),
.S_AXI_AWPROT (S_AXI_AWPROT),
.S_AXI_AWUSER (S_AXI_AWUSER),
.S_AXI_AWVALID (S_AXI_AWVALID),
.S_AXI_AWREADY (S_AXI_AWREADY),
// Master Interface Write Address Port
.M_AXI_AWID (M_AXI_AWID),
.M_AXI_AWADDR (M_AXI_AWADDR),
.M_AXI_AWLEN (M_AXI_AWLEN),
.M_AXI_AWSIZE (M_AXI_AWSIZE),
.M_AXI_AWBURST (M_AXI_AWBURST),
.M_AXI_AWLOCK (M_AXI_AWLOCK),
.M_AXI_AWCACHE (M_AXI_AWCACHE),
.M_AXI_AWPROT (M_AXI_AWPROT),
.M_AXI_AWUSER (M_AXI_AWUSER),
.M_AXI_AWVALID (M_AXI_AWVALID),
.M_AXI_AWREADY (M_AXI_AWREADY)
);
// Write Data channel.
processing_system7_v5_5_w_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_DATA_WIDTH (C_AXI_DATA_WIDTH),
.C_AXI_WUSER_WIDTH (C_AXI_WUSER_WIDTH)
) write_data_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
// Command Interface (Out)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
// Slave Interface Write Data Ports
.S_AXI_WID (S_AXI_WID),
.S_AXI_WDATA (S_AXI_WDATA),
.S_AXI_WSTRB (S_AXI_WSTRB),
.S_AXI_WLAST (S_AXI_WLAST),
.S_AXI_WUSER (S_AXI_WUSER),
.S_AXI_WVALID (S_AXI_WVALID),
.S_AXI_WREADY (S_AXI_WREADY),
// Master Interface Write Data Ports
.M_AXI_WID (M_AXI_WID),
.M_AXI_WDATA (M_AXI_WDATA),
.M_AXI_WSTRB (M_AXI_WSTRB),
.M_AXI_WLAST (M_AXI_WLAST),
.M_AXI_WUSER (M_AXI_WUSER),
.M_AXI_WVALID (M_AXI_WVALID),
.M_AXI_WREADY (M_AXI_WREADY)
);
// Write Response channel.
processing_system7_v5_5_b_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_BUSER_WIDTH (C_AXI_BUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_response_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Response Ports
.S_AXI_BID (S_AXI_BID),
.S_AXI_BRESP (S_AXI_BRESP),
.S_AXI_BUSER (S_AXI_BUSER),
.S_AXI_BVALID (S_AXI_BVALID),
.S_AXI_BREADY (S_AXI_BREADY),
// Master Interface Write Response Ports
.M_AXI_BID (M_AXI_BID),
.M_AXI_BRESP (M_AXI_BRESP),
.M_AXI_BUSER (M_AXI_BUSER),
.M_AXI_BVALID (M_AXI_BVALID),
.M_AXI_BREADY (M_AXI_BREADY),
// Trigger detection
.ERROR_TRIGGER (ERROR_TRIGGER),
.ERROR_TRANSACTION_ID (ERROR_TRANSACTION_ID)
);
/////////////////////////////////////////////////////////////////////////////
// Handle Read Channels (AR/R)
/////////////////////////////////////////////////////////////////////////////
// Read Address Port
assign M_AXI_ARID = S_AXI_ARID;
assign M_AXI_ARADDR = S_AXI_ARADDR;
assign M_AXI_ARLEN = S_AXI_ARLEN;
assign M_AXI_ARSIZE = S_AXI_ARSIZE;
assign M_AXI_ARBURST = S_AXI_ARBURST;
assign M_AXI_ARLOCK = S_AXI_ARLOCK;
assign M_AXI_ARCACHE = S_AXI_ARCACHE;
assign M_AXI_ARPROT = S_AXI_ARPROT;
assign M_AXI_ARUSER = S_AXI_ARUSER;
assign M_AXI_ARVALID = S_AXI_ARVALID;
assign S_AXI_ARREADY = M_AXI_ARREADY;
// Read Data Port
assign S_AXI_RID = M_AXI_RID;
assign S_AXI_RDATA = M_AXI_RDATA;
assign S_AXI_RRESP = M_AXI_RRESP;
assign S_AXI_RLAST = M_AXI_RLAST;
assign S_AXI_RUSER = M_AXI_RUSER;
assign S_AXI_RVALID = M_AXI_RVALID;
assign M_AXI_RREADY = S_AXI_RREADY;
endmodule
|
module processing_system7_v5_5_atc #
(
parameter C_FAMILY = "rtl",
// FPGA Family. Current version: virtex6, spartan6 or later.
parameter integer C_AXI_ID_WIDTH = 4,
// Width of all ID signals on SI and MI side of checker.
// Range: >= 1.
parameter integer C_AXI_ADDR_WIDTH = 32,
// Width of all ADDR signals on SI and MI side of checker.
// Range: 32.
parameter integer C_AXI_DATA_WIDTH = 64,
// Width of all DATA signals on SI and MI side of checker.
// Range: 64.
parameter integer C_AXI_AWUSER_WIDTH = 1,
// Width of AWUSER signals.
// Range: >= 1.
parameter integer C_AXI_ARUSER_WIDTH = 1,
// Width of ARUSER signals.
// Range: >= 1.
parameter integer C_AXI_WUSER_WIDTH = 1,
// Width of WUSER signals.
// Range: >= 1.
parameter integer C_AXI_RUSER_WIDTH = 1,
// Width of RUSER signals.
// Range: >= 1.
parameter integer C_AXI_BUSER_WIDTH = 1
// Width of BUSER signals.
// Range: >= 1.
)
(
// Global Signals
input wire ACLK,
input wire ARESETN,
// Slave Interface Write Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_AWID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_AWADDR,
input wire [4-1:0] S_AXI_AWLEN,
input wire [3-1:0] S_AXI_AWSIZE,
input wire [2-1:0] S_AXI_AWBURST,
input wire [2-1:0] S_AXI_AWLOCK,
input wire [4-1:0] S_AXI_AWCACHE,
input wire [3-1:0] S_AXI_AWPROT,
input wire [C_AXI_AWUSER_WIDTH-1:0] S_AXI_AWUSER,
input wire S_AXI_AWVALID,
output wire S_AXI_AWREADY,
// Slave Interface Write Data Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_WID,
input wire [C_AXI_DATA_WIDTH-1:0] S_AXI_WDATA,
input wire [C_AXI_DATA_WIDTH/8-1:0] S_AXI_WSTRB,
input wire S_AXI_WLAST,
input wire [C_AXI_WUSER_WIDTH-1:0] S_AXI_WUSER,
input wire S_AXI_WVALID,
output wire S_AXI_WREADY,
// Slave Interface Write Response Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_BID,
output wire [2-1:0] S_AXI_BRESP,
output wire [C_AXI_BUSER_WIDTH-1:0] S_AXI_BUSER,
output wire S_AXI_BVALID,
input wire S_AXI_BREADY,
// Slave Interface Read Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_ARID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_ARADDR,
input wire [4-1:0] S_AXI_ARLEN,
input wire [3-1:0] S_AXI_ARSIZE,
input wire [2-1:0] S_AXI_ARBURST,
input wire [2-1:0] S_AXI_ARLOCK,
input wire [4-1:0] S_AXI_ARCACHE,
input wire [3-1:0] S_AXI_ARPROT,
input wire [C_AXI_ARUSER_WIDTH-1:0] S_AXI_ARUSER,
input wire S_AXI_ARVALID,
output wire S_AXI_ARREADY,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Write Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_AWID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_AWADDR,
output wire [4-1:0] M_AXI_AWLEN,
output wire [3-1:0] M_AXI_AWSIZE,
output wire [2-1:0] M_AXI_AWBURST,
output wire [2-1:0] M_AXI_AWLOCK,
output wire [4-1:0] M_AXI_AWCACHE,
output wire [3-1:0] M_AXI_AWPROT,
output wire [C_AXI_AWUSER_WIDTH-1:0] M_AXI_AWUSER,
output wire M_AXI_AWVALID,
input wire M_AXI_AWREADY,
// Master Interface Write Data Ports
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_WID,
output wire [C_AXI_DATA_WIDTH-1:0] M_AXI_WDATA,
output wire [C_AXI_DATA_WIDTH/8-1:0] M_AXI_WSTRB,
output wire M_AXI_WLAST,
output wire [C_AXI_WUSER_WIDTH-1:0] M_AXI_WUSER,
output wire M_AXI_WVALID,
input wire M_AXI_WREADY,
// Master Interface Write Response Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_BID,
input wire [2-1:0] M_AXI_BRESP,
input wire [C_AXI_BUSER_WIDTH-1:0] M_AXI_BUSER,
input wire M_AXI_BVALID,
output wire M_AXI_BREADY,
// Master Interface Read Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_ARID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_ARADDR,
output wire [4-1:0] M_AXI_ARLEN,
output wire [3-1:0] M_AXI_ARSIZE,
output wire [2-1:0] M_AXI_ARBURST,
output wire [2-1:0] M_AXI_ARLOCK,
output wire [4-1:0] M_AXI_ARCACHE,
output wire [3-1:0] M_AXI_ARPROT,
output wire [C_AXI_ARUSER_WIDTH-1:0] M_AXI_ARUSER,
output wire M_AXI_ARVALID,
input wire M_AXI_ARREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY,
output wire ERROR_TRIGGER,
output wire [C_AXI_ID_WIDTH-1:0] ERROR_TRANSACTION_ID
);
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
localparam C_FIFO_DEPTH_LOG = 4;
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Internal reset.
reg ARESET;
// AW->W command queue signals.
wire cmd_w_valid;
wire cmd_w_check;
wire [C_AXI_ID_WIDTH-1:0] cmd_w_id;
wire cmd_w_ready;
// W->B command queue signals.
wire cmd_b_push;
wire cmd_b_error;
wire [C_AXI_ID_WIDTH-1:0] cmd_b_id;
wire cmd_b_full;
wire [C_FIFO_DEPTH_LOG-1:0] cmd_b_addr;
wire cmd_b_ready;
/////////////////////////////////////////////////////////////////////////////
// Handle Internal Reset
/////////////////////////////////////////////////////////////////////////////
always @ (posedge ACLK) begin
ARESET <= !ARESETN;
end
/////////////////////////////////////////////////////////////////////////////
// Handle Write Channels (AW/W/B)
/////////////////////////////////////////////////////////////////////////////
// Write Address Channel.
processing_system7_v5_5_aw_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_ADDR_WIDTH (C_AXI_ADDR_WIDTH),
.C_AXI_AWUSER_WIDTH (C_AXI_AWUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_addr_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (Out)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Address Ports
.S_AXI_AWID (S_AXI_AWID),
.S_AXI_AWADDR (S_AXI_AWADDR),
.S_AXI_AWLEN (S_AXI_AWLEN),
.S_AXI_AWSIZE (S_AXI_AWSIZE),
.S_AXI_AWBURST (S_AXI_AWBURST),
.S_AXI_AWLOCK (S_AXI_AWLOCK),
.S_AXI_AWCACHE (S_AXI_AWCACHE),
.S_AXI_AWPROT (S_AXI_AWPROT),
.S_AXI_AWUSER (S_AXI_AWUSER),
.S_AXI_AWVALID (S_AXI_AWVALID),
.S_AXI_AWREADY (S_AXI_AWREADY),
// Master Interface Write Address Port
.M_AXI_AWID (M_AXI_AWID),
.M_AXI_AWADDR (M_AXI_AWADDR),
.M_AXI_AWLEN (M_AXI_AWLEN),
.M_AXI_AWSIZE (M_AXI_AWSIZE),
.M_AXI_AWBURST (M_AXI_AWBURST),
.M_AXI_AWLOCK (M_AXI_AWLOCK),
.M_AXI_AWCACHE (M_AXI_AWCACHE),
.M_AXI_AWPROT (M_AXI_AWPROT),
.M_AXI_AWUSER (M_AXI_AWUSER),
.M_AXI_AWVALID (M_AXI_AWVALID),
.M_AXI_AWREADY (M_AXI_AWREADY)
);
// Write Data channel.
processing_system7_v5_5_w_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_DATA_WIDTH (C_AXI_DATA_WIDTH),
.C_AXI_WUSER_WIDTH (C_AXI_WUSER_WIDTH)
) write_data_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
// Command Interface (Out)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
// Slave Interface Write Data Ports
.S_AXI_WID (S_AXI_WID),
.S_AXI_WDATA (S_AXI_WDATA),
.S_AXI_WSTRB (S_AXI_WSTRB),
.S_AXI_WLAST (S_AXI_WLAST),
.S_AXI_WUSER (S_AXI_WUSER),
.S_AXI_WVALID (S_AXI_WVALID),
.S_AXI_WREADY (S_AXI_WREADY),
// Master Interface Write Data Ports
.M_AXI_WID (M_AXI_WID),
.M_AXI_WDATA (M_AXI_WDATA),
.M_AXI_WSTRB (M_AXI_WSTRB),
.M_AXI_WLAST (M_AXI_WLAST),
.M_AXI_WUSER (M_AXI_WUSER),
.M_AXI_WVALID (M_AXI_WVALID),
.M_AXI_WREADY (M_AXI_WREADY)
);
// Write Response channel.
processing_system7_v5_5_b_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_BUSER_WIDTH (C_AXI_BUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_response_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Response Ports
.S_AXI_BID (S_AXI_BID),
.S_AXI_BRESP (S_AXI_BRESP),
.S_AXI_BUSER (S_AXI_BUSER),
.S_AXI_BVALID (S_AXI_BVALID),
.S_AXI_BREADY (S_AXI_BREADY),
// Master Interface Write Response Ports
.M_AXI_BID (M_AXI_BID),
.M_AXI_BRESP (M_AXI_BRESP),
.M_AXI_BUSER (M_AXI_BUSER),
.M_AXI_BVALID (M_AXI_BVALID),
.M_AXI_BREADY (M_AXI_BREADY),
// Trigger detection
.ERROR_TRIGGER (ERROR_TRIGGER),
.ERROR_TRANSACTION_ID (ERROR_TRANSACTION_ID)
);
/////////////////////////////////////////////////////////////////////////////
// Handle Read Channels (AR/R)
/////////////////////////////////////////////////////////////////////////////
// Read Address Port
assign M_AXI_ARID = S_AXI_ARID;
assign M_AXI_ARADDR = S_AXI_ARADDR;
assign M_AXI_ARLEN = S_AXI_ARLEN;
assign M_AXI_ARSIZE = S_AXI_ARSIZE;
assign M_AXI_ARBURST = S_AXI_ARBURST;
assign M_AXI_ARLOCK = S_AXI_ARLOCK;
assign M_AXI_ARCACHE = S_AXI_ARCACHE;
assign M_AXI_ARPROT = S_AXI_ARPROT;
assign M_AXI_ARUSER = S_AXI_ARUSER;
assign M_AXI_ARVALID = S_AXI_ARVALID;
assign S_AXI_ARREADY = M_AXI_ARREADY;
// Read Data Port
assign S_AXI_RID = M_AXI_RID;
assign S_AXI_RDATA = M_AXI_RDATA;
assign S_AXI_RRESP = M_AXI_RRESP;
assign S_AXI_RLAST = M_AXI_RLAST;
assign S_AXI_RUSER = M_AXI_RUSER;
assign S_AXI_RVALID = M_AXI_RVALID;
assign M_AXI_RREADY = S_AXI_RREADY;
endmodule
|
module processing_system7_v5_5_atc #
(
parameter C_FAMILY = "rtl",
// FPGA Family. Current version: virtex6, spartan6 or later.
parameter integer C_AXI_ID_WIDTH = 4,
// Width of all ID signals on SI and MI side of checker.
// Range: >= 1.
parameter integer C_AXI_ADDR_WIDTH = 32,
// Width of all ADDR signals on SI and MI side of checker.
// Range: 32.
parameter integer C_AXI_DATA_WIDTH = 64,
// Width of all DATA signals on SI and MI side of checker.
// Range: 64.
parameter integer C_AXI_AWUSER_WIDTH = 1,
// Width of AWUSER signals.
// Range: >= 1.
parameter integer C_AXI_ARUSER_WIDTH = 1,
// Width of ARUSER signals.
// Range: >= 1.
parameter integer C_AXI_WUSER_WIDTH = 1,
// Width of WUSER signals.
// Range: >= 1.
parameter integer C_AXI_RUSER_WIDTH = 1,
// Width of RUSER signals.
// Range: >= 1.
parameter integer C_AXI_BUSER_WIDTH = 1
// Width of BUSER signals.
// Range: >= 1.
)
(
// Global Signals
input wire ACLK,
input wire ARESETN,
// Slave Interface Write Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_AWID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_AWADDR,
input wire [4-1:0] S_AXI_AWLEN,
input wire [3-1:0] S_AXI_AWSIZE,
input wire [2-1:0] S_AXI_AWBURST,
input wire [2-1:0] S_AXI_AWLOCK,
input wire [4-1:0] S_AXI_AWCACHE,
input wire [3-1:0] S_AXI_AWPROT,
input wire [C_AXI_AWUSER_WIDTH-1:0] S_AXI_AWUSER,
input wire S_AXI_AWVALID,
output wire S_AXI_AWREADY,
// Slave Interface Write Data Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_WID,
input wire [C_AXI_DATA_WIDTH-1:0] S_AXI_WDATA,
input wire [C_AXI_DATA_WIDTH/8-1:0] S_AXI_WSTRB,
input wire S_AXI_WLAST,
input wire [C_AXI_WUSER_WIDTH-1:0] S_AXI_WUSER,
input wire S_AXI_WVALID,
output wire S_AXI_WREADY,
// Slave Interface Write Response Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_BID,
output wire [2-1:0] S_AXI_BRESP,
output wire [C_AXI_BUSER_WIDTH-1:0] S_AXI_BUSER,
output wire S_AXI_BVALID,
input wire S_AXI_BREADY,
// Slave Interface Read Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_ARID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_ARADDR,
input wire [4-1:0] S_AXI_ARLEN,
input wire [3-1:0] S_AXI_ARSIZE,
input wire [2-1:0] S_AXI_ARBURST,
input wire [2-1:0] S_AXI_ARLOCK,
input wire [4-1:0] S_AXI_ARCACHE,
input wire [3-1:0] S_AXI_ARPROT,
input wire [C_AXI_ARUSER_WIDTH-1:0] S_AXI_ARUSER,
input wire S_AXI_ARVALID,
output wire S_AXI_ARREADY,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Write Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_AWID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_AWADDR,
output wire [4-1:0] M_AXI_AWLEN,
output wire [3-1:0] M_AXI_AWSIZE,
output wire [2-1:0] M_AXI_AWBURST,
output wire [2-1:0] M_AXI_AWLOCK,
output wire [4-1:0] M_AXI_AWCACHE,
output wire [3-1:0] M_AXI_AWPROT,
output wire [C_AXI_AWUSER_WIDTH-1:0] M_AXI_AWUSER,
output wire M_AXI_AWVALID,
input wire M_AXI_AWREADY,
// Master Interface Write Data Ports
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_WID,
output wire [C_AXI_DATA_WIDTH-1:0] M_AXI_WDATA,
output wire [C_AXI_DATA_WIDTH/8-1:0] M_AXI_WSTRB,
output wire M_AXI_WLAST,
output wire [C_AXI_WUSER_WIDTH-1:0] M_AXI_WUSER,
output wire M_AXI_WVALID,
input wire M_AXI_WREADY,
// Master Interface Write Response Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_BID,
input wire [2-1:0] M_AXI_BRESP,
input wire [C_AXI_BUSER_WIDTH-1:0] M_AXI_BUSER,
input wire M_AXI_BVALID,
output wire M_AXI_BREADY,
// Master Interface Read Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_ARID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_ARADDR,
output wire [4-1:0] M_AXI_ARLEN,
output wire [3-1:0] M_AXI_ARSIZE,
output wire [2-1:0] M_AXI_ARBURST,
output wire [2-1:0] M_AXI_ARLOCK,
output wire [4-1:0] M_AXI_ARCACHE,
output wire [3-1:0] M_AXI_ARPROT,
output wire [C_AXI_ARUSER_WIDTH-1:0] M_AXI_ARUSER,
output wire M_AXI_ARVALID,
input wire M_AXI_ARREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY,
output wire ERROR_TRIGGER,
output wire [C_AXI_ID_WIDTH-1:0] ERROR_TRANSACTION_ID
);
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
localparam C_FIFO_DEPTH_LOG = 4;
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Internal reset.
reg ARESET;
// AW->W command queue signals.
wire cmd_w_valid;
wire cmd_w_check;
wire [C_AXI_ID_WIDTH-1:0] cmd_w_id;
wire cmd_w_ready;
// W->B command queue signals.
wire cmd_b_push;
wire cmd_b_error;
wire [C_AXI_ID_WIDTH-1:0] cmd_b_id;
wire cmd_b_full;
wire [C_FIFO_DEPTH_LOG-1:0] cmd_b_addr;
wire cmd_b_ready;
/////////////////////////////////////////////////////////////////////////////
// Handle Internal Reset
/////////////////////////////////////////////////////////////////////////////
always @ (posedge ACLK) begin
ARESET <= !ARESETN;
end
/////////////////////////////////////////////////////////////////////////////
// Handle Write Channels (AW/W/B)
/////////////////////////////////////////////////////////////////////////////
// Write Address Channel.
processing_system7_v5_5_aw_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_ADDR_WIDTH (C_AXI_ADDR_WIDTH),
.C_AXI_AWUSER_WIDTH (C_AXI_AWUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_addr_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (Out)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Address Ports
.S_AXI_AWID (S_AXI_AWID),
.S_AXI_AWADDR (S_AXI_AWADDR),
.S_AXI_AWLEN (S_AXI_AWLEN),
.S_AXI_AWSIZE (S_AXI_AWSIZE),
.S_AXI_AWBURST (S_AXI_AWBURST),
.S_AXI_AWLOCK (S_AXI_AWLOCK),
.S_AXI_AWCACHE (S_AXI_AWCACHE),
.S_AXI_AWPROT (S_AXI_AWPROT),
.S_AXI_AWUSER (S_AXI_AWUSER),
.S_AXI_AWVALID (S_AXI_AWVALID),
.S_AXI_AWREADY (S_AXI_AWREADY),
// Master Interface Write Address Port
.M_AXI_AWID (M_AXI_AWID),
.M_AXI_AWADDR (M_AXI_AWADDR),
.M_AXI_AWLEN (M_AXI_AWLEN),
.M_AXI_AWSIZE (M_AXI_AWSIZE),
.M_AXI_AWBURST (M_AXI_AWBURST),
.M_AXI_AWLOCK (M_AXI_AWLOCK),
.M_AXI_AWCACHE (M_AXI_AWCACHE),
.M_AXI_AWPROT (M_AXI_AWPROT),
.M_AXI_AWUSER (M_AXI_AWUSER),
.M_AXI_AWVALID (M_AXI_AWVALID),
.M_AXI_AWREADY (M_AXI_AWREADY)
);
// Write Data channel.
processing_system7_v5_5_w_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_DATA_WIDTH (C_AXI_DATA_WIDTH),
.C_AXI_WUSER_WIDTH (C_AXI_WUSER_WIDTH)
) write_data_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
// Command Interface (Out)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
// Slave Interface Write Data Ports
.S_AXI_WID (S_AXI_WID),
.S_AXI_WDATA (S_AXI_WDATA),
.S_AXI_WSTRB (S_AXI_WSTRB),
.S_AXI_WLAST (S_AXI_WLAST),
.S_AXI_WUSER (S_AXI_WUSER),
.S_AXI_WVALID (S_AXI_WVALID),
.S_AXI_WREADY (S_AXI_WREADY),
// Master Interface Write Data Ports
.M_AXI_WID (M_AXI_WID),
.M_AXI_WDATA (M_AXI_WDATA),
.M_AXI_WSTRB (M_AXI_WSTRB),
.M_AXI_WLAST (M_AXI_WLAST),
.M_AXI_WUSER (M_AXI_WUSER),
.M_AXI_WVALID (M_AXI_WVALID),
.M_AXI_WREADY (M_AXI_WREADY)
);
// Write Response channel.
processing_system7_v5_5_b_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_BUSER_WIDTH (C_AXI_BUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_response_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Response Ports
.S_AXI_BID (S_AXI_BID),
.S_AXI_BRESP (S_AXI_BRESP),
.S_AXI_BUSER (S_AXI_BUSER),
.S_AXI_BVALID (S_AXI_BVALID),
.S_AXI_BREADY (S_AXI_BREADY),
// Master Interface Write Response Ports
.M_AXI_BID (M_AXI_BID),
.M_AXI_BRESP (M_AXI_BRESP),
.M_AXI_BUSER (M_AXI_BUSER),
.M_AXI_BVALID (M_AXI_BVALID),
.M_AXI_BREADY (M_AXI_BREADY),
// Trigger detection
.ERROR_TRIGGER (ERROR_TRIGGER),
.ERROR_TRANSACTION_ID (ERROR_TRANSACTION_ID)
);
/////////////////////////////////////////////////////////////////////////////
// Handle Read Channels (AR/R)
/////////////////////////////////////////////////////////////////////////////
// Read Address Port
assign M_AXI_ARID = S_AXI_ARID;
assign M_AXI_ARADDR = S_AXI_ARADDR;
assign M_AXI_ARLEN = S_AXI_ARLEN;
assign M_AXI_ARSIZE = S_AXI_ARSIZE;
assign M_AXI_ARBURST = S_AXI_ARBURST;
assign M_AXI_ARLOCK = S_AXI_ARLOCK;
assign M_AXI_ARCACHE = S_AXI_ARCACHE;
assign M_AXI_ARPROT = S_AXI_ARPROT;
assign M_AXI_ARUSER = S_AXI_ARUSER;
assign M_AXI_ARVALID = S_AXI_ARVALID;
assign S_AXI_ARREADY = M_AXI_ARREADY;
// Read Data Port
assign S_AXI_RID = M_AXI_RID;
assign S_AXI_RDATA = M_AXI_RDATA;
assign S_AXI_RRESP = M_AXI_RRESP;
assign S_AXI_RLAST = M_AXI_RLAST;
assign S_AXI_RUSER = M_AXI_RUSER;
assign S_AXI_RVALID = M_AXI_RVALID;
assign M_AXI_RREADY = S_AXI_RREADY;
endmodule
|
module processing_system7_v5_5_atc #
(
parameter C_FAMILY = "rtl",
// FPGA Family. Current version: virtex6, spartan6 or later.
parameter integer C_AXI_ID_WIDTH = 4,
// Width of all ID signals on SI and MI side of checker.
// Range: >= 1.
parameter integer C_AXI_ADDR_WIDTH = 32,
// Width of all ADDR signals on SI and MI side of checker.
// Range: 32.
parameter integer C_AXI_DATA_WIDTH = 64,
// Width of all DATA signals on SI and MI side of checker.
// Range: 64.
parameter integer C_AXI_AWUSER_WIDTH = 1,
// Width of AWUSER signals.
// Range: >= 1.
parameter integer C_AXI_ARUSER_WIDTH = 1,
// Width of ARUSER signals.
// Range: >= 1.
parameter integer C_AXI_WUSER_WIDTH = 1,
// Width of WUSER signals.
// Range: >= 1.
parameter integer C_AXI_RUSER_WIDTH = 1,
// Width of RUSER signals.
// Range: >= 1.
parameter integer C_AXI_BUSER_WIDTH = 1
// Width of BUSER signals.
// Range: >= 1.
)
(
// Global Signals
input wire ACLK,
input wire ARESETN,
// Slave Interface Write Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_AWID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_AWADDR,
input wire [4-1:0] S_AXI_AWLEN,
input wire [3-1:0] S_AXI_AWSIZE,
input wire [2-1:0] S_AXI_AWBURST,
input wire [2-1:0] S_AXI_AWLOCK,
input wire [4-1:0] S_AXI_AWCACHE,
input wire [3-1:0] S_AXI_AWPROT,
input wire [C_AXI_AWUSER_WIDTH-1:0] S_AXI_AWUSER,
input wire S_AXI_AWVALID,
output wire S_AXI_AWREADY,
// Slave Interface Write Data Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_WID,
input wire [C_AXI_DATA_WIDTH-1:0] S_AXI_WDATA,
input wire [C_AXI_DATA_WIDTH/8-1:0] S_AXI_WSTRB,
input wire S_AXI_WLAST,
input wire [C_AXI_WUSER_WIDTH-1:0] S_AXI_WUSER,
input wire S_AXI_WVALID,
output wire S_AXI_WREADY,
// Slave Interface Write Response Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_BID,
output wire [2-1:0] S_AXI_BRESP,
output wire [C_AXI_BUSER_WIDTH-1:0] S_AXI_BUSER,
output wire S_AXI_BVALID,
input wire S_AXI_BREADY,
// Slave Interface Read Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_ARID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_ARADDR,
input wire [4-1:0] S_AXI_ARLEN,
input wire [3-1:0] S_AXI_ARSIZE,
input wire [2-1:0] S_AXI_ARBURST,
input wire [2-1:0] S_AXI_ARLOCK,
input wire [4-1:0] S_AXI_ARCACHE,
input wire [3-1:0] S_AXI_ARPROT,
input wire [C_AXI_ARUSER_WIDTH-1:0] S_AXI_ARUSER,
input wire S_AXI_ARVALID,
output wire S_AXI_ARREADY,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Write Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_AWID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_AWADDR,
output wire [4-1:0] M_AXI_AWLEN,
output wire [3-1:0] M_AXI_AWSIZE,
output wire [2-1:0] M_AXI_AWBURST,
output wire [2-1:0] M_AXI_AWLOCK,
output wire [4-1:0] M_AXI_AWCACHE,
output wire [3-1:0] M_AXI_AWPROT,
output wire [C_AXI_AWUSER_WIDTH-1:0] M_AXI_AWUSER,
output wire M_AXI_AWVALID,
input wire M_AXI_AWREADY,
// Master Interface Write Data Ports
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_WID,
output wire [C_AXI_DATA_WIDTH-1:0] M_AXI_WDATA,
output wire [C_AXI_DATA_WIDTH/8-1:0] M_AXI_WSTRB,
output wire M_AXI_WLAST,
output wire [C_AXI_WUSER_WIDTH-1:0] M_AXI_WUSER,
output wire M_AXI_WVALID,
input wire M_AXI_WREADY,
// Master Interface Write Response Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_BID,
input wire [2-1:0] M_AXI_BRESP,
input wire [C_AXI_BUSER_WIDTH-1:0] M_AXI_BUSER,
input wire M_AXI_BVALID,
output wire M_AXI_BREADY,
// Master Interface Read Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_ARID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_ARADDR,
output wire [4-1:0] M_AXI_ARLEN,
output wire [3-1:0] M_AXI_ARSIZE,
output wire [2-1:0] M_AXI_ARBURST,
output wire [2-1:0] M_AXI_ARLOCK,
output wire [4-1:0] M_AXI_ARCACHE,
output wire [3-1:0] M_AXI_ARPROT,
output wire [C_AXI_ARUSER_WIDTH-1:0] M_AXI_ARUSER,
output wire M_AXI_ARVALID,
input wire M_AXI_ARREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY,
output wire ERROR_TRIGGER,
output wire [C_AXI_ID_WIDTH-1:0] ERROR_TRANSACTION_ID
);
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
localparam C_FIFO_DEPTH_LOG = 4;
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Internal reset.
reg ARESET;
// AW->W command queue signals.
wire cmd_w_valid;
wire cmd_w_check;
wire [C_AXI_ID_WIDTH-1:0] cmd_w_id;
wire cmd_w_ready;
// W->B command queue signals.
wire cmd_b_push;
wire cmd_b_error;
wire [C_AXI_ID_WIDTH-1:0] cmd_b_id;
wire cmd_b_full;
wire [C_FIFO_DEPTH_LOG-1:0] cmd_b_addr;
wire cmd_b_ready;
/////////////////////////////////////////////////////////////////////////////
// Handle Internal Reset
/////////////////////////////////////////////////////////////////////////////
always @ (posedge ACLK) begin
ARESET <= !ARESETN;
end
/////////////////////////////////////////////////////////////////////////////
// Handle Write Channels (AW/W/B)
/////////////////////////////////////////////////////////////////////////////
// Write Address Channel.
processing_system7_v5_5_aw_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_ADDR_WIDTH (C_AXI_ADDR_WIDTH),
.C_AXI_AWUSER_WIDTH (C_AXI_AWUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_addr_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (Out)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Address Ports
.S_AXI_AWID (S_AXI_AWID),
.S_AXI_AWADDR (S_AXI_AWADDR),
.S_AXI_AWLEN (S_AXI_AWLEN),
.S_AXI_AWSIZE (S_AXI_AWSIZE),
.S_AXI_AWBURST (S_AXI_AWBURST),
.S_AXI_AWLOCK (S_AXI_AWLOCK),
.S_AXI_AWCACHE (S_AXI_AWCACHE),
.S_AXI_AWPROT (S_AXI_AWPROT),
.S_AXI_AWUSER (S_AXI_AWUSER),
.S_AXI_AWVALID (S_AXI_AWVALID),
.S_AXI_AWREADY (S_AXI_AWREADY),
// Master Interface Write Address Port
.M_AXI_AWID (M_AXI_AWID),
.M_AXI_AWADDR (M_AXI_AWADDR),
.M_AXI_AWLEN (M_AXI_AWLEN),
.M_AXI_AWSIZE (M_AXI_AWSIZE),
.M_AXI_AWBURST (M_AXI_AWBURST),
.M_AXI_AWLOCK (M_AXI_AWLOCK),
.M_AXI_AWCACHE (M_AXI_AWCACHE),
.M_AXI_AWPROT (M_AXI_AWPROT),
.M_AXI_AWUSER (M_AXI_AWUSER),
.M_AXI_AWVALID (M_AXI_AWVALID),
.M_AXI_AWREADY (M_AXI_AWREADY)
);
// Write Data channel.
processing_system7_v5_5_w_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_DATA_WIDTH (C_AXI_DATA_WIDTH),
.C_AXI_WUSER_WIDTH (C_AXI_WUSER_WIDTH)
) write_data_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
// Command Interface (Out)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
// Slave Interface Write Data Ports
.S_AXI_WID (S_AXI_WID),
.S_AXI_WDATA (S_AXI_WDATA),
.S_AXI_WSTRB (S_AXI_WSTRB),
.S_AXI_WLAST (S_AXI_WLAST),
.S_AXI_WUSER (S_AXI_WUSER),
.S_AXI_WVALID (S_AXI_WVALID),
.S_AXI_WREADY (S_AXI_WREADY),
// Master Interface Write Data Ports
.M_AXI_WID (M_AXI_WID),
.M_AXI_WDATA (M_AXI_WDATA),
.M_AXI_WSTRB (M_AXI_WSTRB),
.M_AXI_WLAST (M_AXI_WLAST),
.M_AXI_WUSER (M_AXI_WUSER),
.M_AXI_WVALID (M_AXI_WVALID),
.M_AXI_WREADY (M_AXI_WREADY)
);
// Write Response channel.
processing_system7_v5_5_b_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_BUSER_WIDTH (C_AXI_BUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_response_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Response Ports
.S_AXI_BID (S_AXI_BID),
.S_AXI_BRESP (S_AXI_BRESP),
.S_AXI_BUSER (S_AXI_BUSER),
.S_AXI_BVALID (S_AXI_BVALID),
.S_AXI_BREADY (S_AXI_BREADY),
// Master Interface Write Response Ports
.M_AXI_BID (M_AXI_BID),
.M_AXI_BRESP (M_AXI_BRESP),
.M_AXI_BUSER (M_AXI_BUSER),
.M_AXI_BVALID (M_AXI_BVALID),
.M_AXI_BREADY (M_AXI_BREADY),
// Trigger detection
.ERROR_TRIGGER (ERROR_TRIGGER),
.ERROR_TRANSACTION_ID (ERROR_TRANSACTION_ID)
);
/////////////////////////////////////////////////////////////////////////////
// Handle Read Channels (AR/R)
/////////////////////////////////////////////////////////////////////////////
// Read Address Port
assign M_AXI_ARID = S_AXI_ARID;
assign M_AXI_ARADDR = S_AXI_ARADDR;
assign M_AXI_ARLEN = S_AXI_ARLEN;
assign M_AXI_ARSIZE = S_AXI_ARSIZE;
assign M_AXI_ARBURST = S_AXI_ARBURST;
assign M_AXI_ARLOCK = S_AXI_ARLOCK;
assign M_AXI_ARCACHE = S_AXI_ARCACHE;
assign M_AXI_ARPROT = S_AXI_ARPROT;
assign M_AXI_ARUSER = S_AXI_ARUSER;
assign M_AXI_ARVALID = S_AXI_ARVALID;
assign S_AXI_ARREADY = M_AXI_ARREADY;
// Read Data Port
assign S_AXI_RID = M_AXI_RID;
assign S_AXI_RDATA = M_AXI_RDATA;
assign S_AXI_RRESP = M_AXI_RRESP;
assign S_AXI_RLAST = M_AXI_RLAST;
assign S_AXI_RUSER = M_AXI_RUSER;
assign S_AXI_RVALID = M_AXI_RVALID;
assign M_AXI_RREADY = S_AXI_RREADY;
endmodule
|
module processing_system7_v5_5_atc #
(
parameter C_FAMILY = "rtl",
// FPGA Family. Current version: virtex6, spartan6 or later.
parameter integer C_AXI_ID_WIDTH = 4,
// Width of all ID signals on SI and MI side of checker.
// Range: >= 1.
parameter integer C_AXI_ADDR_WIDTH = 32,
// Width of all ADDR signals on SI and MI side of checker.
// Range: 32.
parameter integer C_AXI_DATA_WIDTH = 64,
// Width of all DATA signals on SI and MI side of checker.
// Range: 64.
parameter integer C_AXI_AWUSER_WIDTH = 1,
// Width of AWUSER signals.
// Range: >= 1.
parameter integer C_AXI_ARUSER_WIDTH = 1,
// Width of ARUSER signals.
// Range: >= 1.
parameter integer C_AXI_WUSER_WIDTH = 1,
// Width of WUSER signals.
// Range: >= 1.
parameter integer C_AXI_RUSER_WIDTH = 1,
// Width of RUSER signals.
// Range: >= 1.
parameter integer C_AXI_BUSER_WIDTH = 1
// Width of BUSER signals.
// Range: >= 1.
)
(
// Global Signals
input wire ACLK,
input wire ARESETN,
// Slave Interface Write Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_AWID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_AWADDR,
input wire [4-1:0] S_AXI_AWLEN,
input wire [3-1:0] S_AXI_AWSIZE,
input wire [2-1:0] S_AXI_AWBURST,
input wire [2-1:0] S_AXI_AWLOCK,
input wire [4-1:0] S_AXI_AWCACHE,
input wire [3-1:0] S_AXI_AWPROT,
input wire [C_AXI_AWUSER_WIDTH-1:0] S_AXI_AWUSER,
input wire S_AXI_AWVALID,
output wire S_AXI_AWREADY,
// Slave Interface Write Data Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_WID,
input wire [C_AXI_DATA_WIDTH-1:0] S_AXI_WDATA,
input wire [C_AXI_DATA_WIDTH/8-1:0] S_AXI_WSTRB,
input wire S_AXI_WLAST,
input wire [C_AXI_WUSER_WIDTH-1:0] S_AXI_WUSER,
input wire S_AXI_WVALID,
output wire S_AXI_WREADY,
// Slave Interface Write Response Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_BID,
output wire [2-1:0] S_AXI_BRESP,
output wire [C_AXI_BUSER_WIDTH-1:0] S_AXI_BUSER,
output wire S_AXI_BVALID,
input wire S_AXI_BREADY,
// Slave Interface Read Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_ARID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_ARADDR,
input wire [4-1:0] S_AXI_ARLEN,
input wire [3-1:0] S_AXI_ARSIZE,
input wire [2-1:0] S_AXI_ARBURST,
input wire [2-1:0] S_AXI_ARLOCK,
input wire [4-1:0] S_AXI_ARCACHE,
input wire [3-1:0] S_AXI_ARPROT,
input wire [C_AXI_ARUSER_WIDTH-1:0] S_AXI_ARUSER,
input wire S_AXI_ARVALID,
output wire S_AXI_ARREADY,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Write Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_AWID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_AWADDR,
output wire [4-1:0] M_AXI_AWLEN,
output wire [3-1:0] M_AXI_AWSIZE,
output wire [2-1:0] M_AXI_AWBURST,
output wire [2-1:0] M_AXI_AWLOCK,
output wire [4-1:0] M_AXI_AWCACHE,
output wire [3-1:0] M_AXI_AWPROT,
output wire [C_AXI_AWUSER_WIDTH-1:0] M_AXI_AWUSER,
output wire M_AXI_AWVALID,
input wire M_AXI_AWREADY,
// Master Interface Write Data Ports
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_WID,
output wire [C_AXI_DATA_WIDTH-1:0] M_AXI_WDATA,
output wire [C_AXI_DATA_WIDTH/8-1:0] M_AXI_WSTRB,
output wire M_AXI_WLAST,
output wire [C_AXI_WUSER_WIDTH-1:0] M_AXI_WUSER,
output wire M_AXI_WVALID,
input wire M_AXI_WREADY,
// Master Interface Write Response Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_BID,
input wire [2-1:0] M_AXI_BRESP,
input wire [C_AXI_BUSER_WIDTH-1:0] M_AXI_BUSER,
input wire M_AXI_BVALID,
output wire M_AXI_BREADY,
// Master Interface Read Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_ARID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_ARADDR,
output wire [4-1:0] M_AXI_ARLEN,
output wire [3-1:0] M_AXI_ARSIZE,
output wire [2-1:0] M_AXI_ARBURST,
output wire [2-1:0] M_AXI_ARLOCK,
output wire [4-1:0] M_AXI_ARCACHE,
output wire [3-1:0] M_AXI_ARPROT,
output wire [C_AXI_ARUSER_WIDTH-1:0] M_AXI_ARUSER,
output wire M_AXI_ARVALID,
input wire M_AXI_ARREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY,
output wire ERROR_TRIGGER,
output wire [C_AXI_ID_WIDTH-1:0] ERROR_TRANSACTION_ID
);
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
localparam C_FIFO_DEPTH_LOG = 4;
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Internal reset.
reg ARESET;
// AW->W command queue signals.
wire cmd_w_valid;
wire cmd_w_check;
wire [C_AXI_ID_WIDTH-1:0] cmd_w_id;
wire cmd_w_ready;
// W->B command queue signals.
wire cmd_b_push;
wire cmd_b_error;
wire [C_AXI_ID_WIDTH-1:0] cmd_b_id;
wire cmd_b_full;
wire [C_FIFO_DEPTH_LOG-1:0] cmd_b_addr;
wire cmd_b_ready;
/////////////////////////////////////////////////////////////////////////////
// Handle Internal Reset
/////////////////////////////////////////////////////////////////////////////
always @ (posedge ACLK) begin
ARESET <= !ARESETN;
end
/////////////////////////////////////////////////////////////////////////////
// Handle Write Channels (AW/W/B)
/////////////////////////////////////////////////////////////////////////////
// Write Address Channel.
processing_system7_v5_5_aw_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_ADDR_WIDTH (C_AXI_ADDR_WIDTH),
.C_AXI_AWUSER_WIDTH (C_AXI_AWUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_addr_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (Out)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Address Ports
.S_AXI_AWID (S_AXI_AWID),
.S_AXI_AWADDR (S_AXI_AWADDR),
.S_AXI_AWLEN (S_AXI_AWLEN),
.S_AXI_AWSIZE (S_AXI_AWSIZE),
.S_AXI_AWBURST (S_AXI_AWBURST),
.S_AXI_AWLOCK (S_AXI_AWLOCK),
.S_AXI_AWCACHE (S_AXI_AWCACHE),
.S_AXI_AWPROT (S_AXI_AWPROT),
.S_AXI_AWUSER (S_AXI_AWUSER),
.S_AXI_AWVALID (S_AXI_AWVALID),
.S_AXI_AWREADY (S_AXI_AWREADY),
// Master Interface Write Address Port
.M_AXI_AWID (M_AXI_AWID),
.M_AXI_AWADDR (M_AXI_AWADDR),
.M_AXI_AWLEN (M_AXI_AWLEN),
.M_AXI_AWSIZE (M_AXI_AWSIZE),
.M_AXI_AWBURST (M_AXI_AWBURST),
.M_AXI_AWLOCK (M_AXI_AWLOCK),
.M_AXI_AWCACHE (M_AXI_AWCACHE),
.M_AXI_AWPROT (M_AXI_AWPROT),
.M_AXI_AWUSER (M_AXI_AWUSER),
.M_AXI_AWVALID (M_AXI_AWVALID),
.M_AXI_AWREADY (M_AXI_AWREADY)
);
// Write Data channel.
processing_system7_v5_5_w_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_DATA_WIDTH (C_AXI_DATA_WIDTH),
.C_AXI_WUSER_WIDTH (C_AXI_WUSER_WIDTH)
) write_data_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
// Command Interface (Out)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
// Slave Interface Write Data Ports
.S_AXI_WID (S_AXI_WID),
.S_AXI_WDATA (S_AXI_WDATA),
.S_AXI_WSTRB (S_AXI_WSTRB),
.S_AXI_WLAST (S_AXI_WLAST),
.S_AXI_WUSER (S_AXI_WUSER),
.S_AXI_WVALID (S_AXI_WVALID),
.S_AXI_WREADY (S_AXI_WREADY),
// Master Interface Write Data Ports
.M_AXI_WID (M_AXI_WID),
.M_AXI_WDATA (M_AXI_WDATA),
.M_AXI_WSTRB (M_AXI_WSTRB),
.M_AXI_WLAST (M_AXI_WLAST),
.M_AXI_WUSER (M_AXI_WUSER),
.M_AXI_WVALID (M_AXI_WVALID),
.M_AXI_WREADY (M_AXI_WREADY)
);
// Write Response channel.
processing_system7_v5_5_b_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_BUSER_WIDTH (C_AXI_BUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_response_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Response Ports
.S_AXI_BID (S_AXI_BID),
.S_AXI_BRESP (S_AXI_BRESP),
.S_AXI_BUSER (S_AXI_BUSER),
.S_AXI_BVALID (S_AXI_BVALID),
.S_AXI_BREADY (S_AXI_BREADY),
// Master Interface Write Response Ports
.M_AXI_BID (M_AXI_BID),
.M_AXI_BRESP (M_AXI_BRESP),
.M_AXI_BUSER (M_AXI_BUSER),
.M_AXI_BVALID (M_AXI_BVALID),
.M_AXI_BREADY (M_AXI_BREADY),
// Trigger detection
.ERROR_TRIGGER (ERROR_TRIGGER),
.ERROR_TRANSACTION_ID (ERROR_TRANSACTION_ID)
);
/////////////////////////////////////////////////////////////////////////////
// Handle Read Channels (AR/R)
/////////////////////////////////////////////////////////////////////////////
// Read Address Port
assign M_AXI_ARID = S_AXI_ARID;
assign M_AXI_ARADDR = S_AXI_ARADDR;
assign M_AXI_ARLEN = S_AXI_ARLEN;
assign M_AXI_ARSIZE = S_AXI_ARSIZE;
assign M_AXI_ARBURST = S_AXI_ARBURST;
assign M_AXI_ARLOCK = S_AXI_ARLOCK;
assign M_AXI_ARCACHE = S_AXI_ARCACHE;
assign M_AXI_ARPROT = S_AXI_ARPROT;
assign M_AXI_ARUSER = S_AXI_ARUSER;
assign M_AXI_ARVALID = S_AXI_ARVALID;
assign S_AXI_ARREADY = M_AXI_ARREADY;
// Read Data Port
assign S_AXI_RID = M_AXI_RID;
assign S_AXI_RDATA = M_AXI_RDATA;
assign S_AXI_RRESP = M_AXI_RRESP;
assign S_AXI_RLAST = M_AXI_RLAST;
assign S_AXI_RUSER = M_AXI_RUSER;
assign S_AXI_RVALID = M_AXI_RVALID;
assign M_AXI_RREADY = S_AXI_RREADY;
endmodule
|
module processing_system7_v5_5_atc #
(
parameter C_FAMILY = "rtl",
// FPGA Family. Current version: virtex6, spartan6 or later.
parameter integer C_AXI_ID_WIDTH = 4,
// Width of all ID signals on SI and MI side of checker.
// Range: >= 1.
parameter integer C_AXI_ADDR_WIDTH = 32,
// Width of all ADDR signals on SI and MI side of checker.
// Range: 32.
parameter integer C_AXI_DATA_WIDTH = 64,
// Width of all DATA signals on SI and MI side of checker.
// Range: 64.
parameter integer C_AXI_AWUSER_WIDTH = 1,
// Width of AWUSER signals.
// Range: >= 1.
parameter integer C_AXI_ARUSER_WIDTH = 1,
// Width of ARUSER signals.
// Range: >= 1.
parameter integer C_AXI_WUSER_WIDTH = 1,
// Width of WUSER signals.
// Range: >= 1.
parameter integer C_AXI_RUSER_WIDTH = 1,
// Width of RUSER signals.
// Range: >= 1.
parameter integer C_AXI_BUSER_WIDTH = 1
// Width of BUSER signals.
// Range: >= 1.
)
(
// Global Signals
input wire ACLK,
input wire ARESETN,
// Slave Interface Write Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_AWID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_AWADDR,
input wire [4-1:0] S_AXI_AWLEN,
input wire [3-1:0] S_AXI_AWSIZE,
input wire [2-1:0] S_AXI_AWBURST,
input wire [2-1:0] S_AXI_AWLOCK,
input wire [4-1:0] S_AXI_AWCACHE,
input wire [3-1:0] S_AXI_AWPROT,
input wire [C_AXI_AWUSER_WIDTH-1:0] S_AXI_AWUSER,
input wire S_AXI_AWVALID,
output wire S_AXI_AWREADY,
// Slave Interface Write Data Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_WID,
input wire [C_AXI_DATA_WIDTH-1:0] S_AXI_WDATA,
input wire [C_AXI_DATA_WIDTH/8-1:0] S_AXI_WSTRB,
input wire S_AXI_WLAST,
input wire [C_AXI_WUSER_WIDTH-1:0] S_AXI_WUSER,
input wire S_AXI_WVALID,
output wire S_AXI_WREADY,
// Slave Interface Write Response Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_BID,
output wire [2-1:0] S_AXI_BRESP,
output wire [C_AXI_BUSER_WIDTH-1:0] S_AXI_BUSER,
output wire S_AXI_BVALID,
input wire S_AXI_BREADY,
// Slave Interface Read Address Ports
input wire [C_AXI_ID_WIDTH-1:0] S_AXI_ARID,
input wire [C_AXI_ADDR_WIDTH-1:0] S_AXI_ARADDR,
input wire [4-1:0] S_AXI_ARLEN,
input wire [3-1:0] S_AXI_ARSIZE,
input wire [2-1:0] S_AXI_ARBURST,
input wire [2-1:0] S_AXI_ARLOCK,
input wire [4-1:0] S_AXI_ARCACHE,
input wire [3-1:0] S_AXI_ARPROT,
input wire [C_AXI_ARUSER_WIDTH-1:0] S_AXI_ARUSER,
input wire S_AXI_ARVALID,
output wire S_AXI_ARREADY,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Write Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_AWID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_AWADDR,
output wire [4-1:0] M_AXI_AWLEN,
output wire [3-1:0] M_AXI_AWSIZE,
output wire [2-1:0] M_AXI_AWBURST,
output wire [2-1:0] M_AXI_AWLOCK,
output wire [4-1:0] M_AXI_AWCACHE,
output wire [3-1:0] M_AXI_AWPROT,
output wire [C_AXI_AWUSER_WIDTH-1:0] M_AXI_AWUSER,
output wire M_AXI_AWVALID,
input wire M_AXI_AWREADY,
// Master Interface Write Data Ports
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_WID,
output wire [C_AXI_DATA_WIDTH-1:0] M_AXI_WDATA,
output wire [C_AXI_DATA_WIDTH/8-1:0] M_AXI_WSTRB,
output wire M_AXI_WLAST,
output wire [C_AXI_WUSER_WIDTH-1:0] M_AXI_WUSER,
output wire M_AXI_WVALID,
input wire M_AXI_WREADY,
// Master Interface Write Response Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_BID,
input wire [2-1:0] M_AXI_BRESP,
input wire [C_AXI_BUSER_WIDTH-1:0] M_AXI_BUSER,
input wire M_AXI_BVALID,
output wire M_AXI_BREADY,
// Master Interface Read Address Port
output wire [C_AXI_ID_WIDTH-1:0] M_AXI_ARID,
output wire [C_AXI_ADDR_WIDTH-1:0] M_AXI_ARADDR,
output wire [4-1:0] M_AXI_ARLEN,
output wire [3-1:0] M_AXI_ARSIZE,
output wire [2-1:0] M_AXI_ARBURST,
output wire [2-1:0] M_AXI_ARLOCK,
output wire [4-1:0] M_AXI_ARCACHE,
output wire [3-1:0] M_AXI_ARPROT,
output wire [C_AXI_ARUSER_WIDTH-1:0] M_AXI_ARUSER,
output wire M_AXI_ARVALID,
input wire M_AXI_ARREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY,
output wire ERROR_TRIGGER,
output wire [C_AXI_ID_WIDTH-1:0] ERROR_TRANSACTION_ID
);
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
localparam C_FIFO_DEPTH_LOG = 4;
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Internal reset.
reg ARESET;
// AW->W command queue signals.
wire cmd_w_valid;
wire cmd_w_check;
wire [C_AXI_ID_WIDTH-1:0] cmd_w_id;
wire cmd_w_ready;
// W->B command queue signals.
wire cmd_b_push;
wire cmd_b_error;
wire [C_AXI_ID_WIDTH-1:0] cmd_b_id;
wire cmd_b_full;
wire [C_FIFO_DEPTH_LOG-1:0] cmd_b_addr;
wire cmd_b_ready;
/////////////////////////////////////////////////////////////////////////////
// Handle Internal Reset
/////////////////////////////////////////////////////////////////////////////
always @ (posedge ACLK) begin
ARESET <= !ARESETN;
end
/////////////////////////////////////////////////////////////////////////////
// Handle Write Channels (AW/W/B)
/////////////////////////////////////////////////////////////////////////////
// Write Address Channel.
processing_system7_v5_5_aw_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_ADDR_WIDTH (C_AXI_ADDR_WIDTH),
.C_AXI_AWUSER_WIDTH (C_AXI_AWUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_addr_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (Out)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Address Ports
.S_AXI_AWID (S_AXI_AWID),
.S_AXI_AWADDR (S_AXI_AWADDR),
.S_AXI_AWLEN (S_AXI_AWLEN),
.S_AXI_AWSIZE (S_AXI_AWSIZE),
.S_AXI_AWBURST (S_AXI_AWBURST),
.S_AXI_AWLOCK (S_AXI_AWLOCK),
.S_AXI_AWCACHE (S_AXI_AWCACHE),
.S_AXI_AWPROT (S_AXI_AWPROT),
.S_AXI_AWUSER (S_AXI_AWUSER),
.S_AXI_AWVALID (S_AXI_AWVALID),
.S_AXI_AWREADY (S_AXI_AWREADY),
// Master Interface Write Address Port
.M_AXI_AWID (M_AXI_AWID),
.M_AXI_AWADDR (M_AXI_AWADDR),
.M_AXI_AWLEN (M_AXI_AWLEN),
.M_AXI_AWSIZE (M_AXI_AWSIZE),
.M_AXI_AWBURST (M_AXI_AWBURST),
.M_AXI_AWLOCK (M_AXI_AWLOCK),
.M_AXI_AWCACHE (M_AXI_AWCACHE),
.M_AXI_AWPROT (M_AXI_AWPROT),
.M_AXI_AWUSER (M_AXI_AWUSER),
.M_AXI_AWVALID (M_AXI_AWVALID),
.M_AXI_AWREADY (M_AXI_AWREADY)
);
// Write Data channel.
processing_system7_v5_5_w_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_DATA_WIDTH (C_AXI_DATA_WIDTH),
.C_AXI_WUSER_WIDTH (C_AXI_WUSER_WIDTH)
) write_data_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_w_valid (cmd_w_valid),
.cmd_w_check (cmd_w_check),
.cmd_w_id (cmd_w_id),
.cmd_w_ready (cmd_w_ready),
// Command Interface (Out)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
// Slave Interface Write Data Ports
.S_AXI_WID (S_AXI_WID),
.S_AXI_WDATA (S_AXI_WDATA),
.S_AXI_WSTRB (S_AXI_WSTRB),
.S_AXI_WLAST (S_AXI_WLAST),
.S_AXI_WUSER (S_AXI_WUSER),
.S_AXI_WVALID (S_AXI_WVALID),
.S_AXI_WREADY (S_AXI_WREADY),
// Master Interface Write Data Ports
.M_AXI_WID (M_AXI_WID),
.M_AXI_WDATA (M_AXI_WDATA),
.M_AXI_WSTRB (M_AXI_WSTRB),
.M_AXI_WLAST (M_AXI_WLAST),
.M_AXI_WUSER (M_AXI_WUSER),
.M_AXI_WVALID (M_AXI_WVALID),
.M_AXI_WREADY (M_AXI_WREADY)
);
// Write Response channel.
processing_system7_v5_5_b_atc #
(
.C_FAMILY (C_FAMILY),
.C_AXI_ID_WIDTH (C_AXI_ID_WIDTH),
.C_AXI_BUSER_WIDTH (C_AXI_BUSER_WIDTH),
.C_FIFO_DEPTH_LOG (C_FIFO_DEPTH_LOG)
) write_response_inst
(
// Global Signals
.ARESET (ARESET),
.ACLK (ACLK),
// Command Interface (In)
.cmd_b_push (cmd_b_push),
.cmd_b_error (cmd_b_error),
.cmd_b_id (cmd_b_id),
.cmd_b_full (cmd_b_full),
.cmd_b_addr (cmd_b_addr),
.cmd_b_ready (cmd_b_ready),
// Slave Interface Write Response Ports
.S_AXI_BID (S_AXI_BID),
.S_AXI_BRESP (S_AXI_BRESP),
.S_AXI_BUSER (S_AXI_BUSER),
.S_AXI_BVALID (S_AXI_BVALID),
.S_AXI_BREADY (S_AXI_BREADY),
// Master Interface Write Response Ports
.M_AXI_BID (M_AXI_BID),
.M_AXI_BRESP (M_AXI_BRESP),
.M_AXI_BUSER (M_AXI_BUSER),
.M_AXI_BVALID (M_AXI_BVALID),
.M_AXI_BREADY (M_AXI_BREADY),
// Trigger detection
.ERROR_TRIGGER (ERROR_TRIGGER),
.ERROR_TRANSACTION_ID (ERROR_TRANSACTION_ID)
);
/////////////////////////////////////////////////////////////////////////////
// Handle Read Channels (AR/R)
/////////////////////////////////////////////////////////////////////////////
// Read Address Port
assign M_AXI_ARID = S_AXI_ARID;
assign M_AXI_ARADDR = S_AXI_ARADDR;
assign M_AXI_ARLEN = S_AXI_ARLEN;
assign M_AXI_ARSIZE = S_AXI_ARSIZE;
assign M_AXI_ARBURST = S_AXI_ARBURST;
assign M_AXI_ARLOCK = S_AXI_ARLOCK;
assign M_AXI_ARCACHE = S_AXI_ARCACHE;
assign M_AXI_ARPROT = S_AXI_ARPROT;
assign M_AXI_ARUSER = S_AXI_ARUSER;
assign M_AXI_ARVALID = S_AXI_ARVALID;
assign S_AXI_ARREADY = M_AXI_ARREADY;
// Read Data Port
assign S_AXI_RID = M_AXI_RID;
assign S_AXI_RDATA = M_AXI_RDATA;
assign S_AXI_RRESP = M_AXI_RRESP;
assign S_AXI_RLAST = M_AXI_RLAST;
assign S_AXI_RUSER = M_AXI_RUSER;
assign S_AXI_RVALID = M_AXI_RVALID;
assign M_AXI_RREADY = S_AXI_RREADY;
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module altera_avalon_sc_fifo
#(
// --------------------------------------------------
// Parameters
// --------------------------------------------------
parameter SYMBOLS_PER_BEAT = 1,
parameter BITS_PER_SYMBOL = 8,
parameter FIFO_DEPTH = 16,
parameter CHANNEL_WIDTH = 0,
parameter ERROR_WIDTH = 0,
parameter USE_PACKETS = 0,
parameter USE_FILL_LEVEL = 0,
parameter USE_STORE_FORWARD = 0,
parameter USE_ALMOST_FULL_IF = 0,
parameter USE_ALMOST_EMPTY_IF = 0,
// --------------------------------------------------
// Empty latency is defined as the number of cycles
// required for a write to deassert the empty flag.
// For example, a latency of 1 means that the empty
// flag is deasserted on the cycle after a write.
//
// Another way to think of it is the latency for a
// write to propagate to the output.
//
// An empty latency of 0 implies lookahead, which is
// only implemented for the register-based FIFO.
// --------------------------------------------------
parameter EMPTY_LATENCY = 3,
parameter USE_MEMORY_BLOCKS = 1,
// --------------------------------------------------
// Internal Parameters
// --------------------------------------------------
parameter DATA_WIDTH = SYMBOLS_PER_BEAT * BITS_PER_SYMBOL,
parameter EMPTY_WIDTH = log2ceil(SYMBOLS_PER_BEAT)
)
(
// --------------------------------------------------
// Ports
// --------------------------------------------------
input clk,
input reset,
input [DATA_WIDTH-1: 0] in_data,
input in_valid,
input in_startofpacket,
input in_endofpacket,
input [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] in_empty,
input [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] in_error,
input [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] in_channel,
output in_ready,
output [DATA_WIDTH-1 : 0] out_data,
output reg out_valid,
output out_startofpacket,
output out_endofpacket,
output [((EMPTY_WIDTH>0) ? (EMPTY_WIDTH-1):0) : 0] out_empty,
output [((ERROR_WIDTH>0) ? (ERROR_WIDTH-1):0) : 0] out_error,
output [((CHANNEL_WIDTH>0) ? (CHANNEL_WIDTH-1):0): 0] out_channel,
input out_ready,
input [(USE_STORE_FORWARD ? 2 : 1) : 0] csr_address,
input csr_write,
input csr_read,
input [31 : 0] csr_writedata,
output reg [31 : 0] csr_readdata,
output wire almost_full_data,
output wire almost_empty_data
);
// --------------------------------------------------
// Local Parameters
// --------------------------------------------------
localparam ADDR_WIDTH = log2ceil(FIFO_DEPTH);
localparam DEPTH = FIFO_DEPTH;
localparam PKT_SIGNALS_WIDTH = 2 + EMPTY_WIDTH;
localparam PAYLOAD_WIDTH = (USE_PACKETS == 1) ?
2 + EMPTY_WIDTH + DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH:
DATA_WIDTH + ERROR_WIDTH + CHANNEL_WIDTH;
// --------------------------------------------------
// Internal Signals
// --------------------------------------------------
genvar i;
reg [PAYLOAD_WIDTH-1 : 0] mem [DEPTH-1 : 0];
reg [ADDR_WIDTH-1 : 0] wr_ptr;
reg [ADDR_WIDTH-1 : 0] rd_ptr;
reg [DEPTH-1 : 0] mem_used;
wire [ADDR_WIDTH-1 : 0] next_wr_ptr;
wire [ADDR_WIDTH-1 : 0] next_rd_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_wr_ptr;
wire [ADDR_WIDTH-1 : 0] incremented_rd_ptr;
wire [ADDR_WIDTH-1 : 0] mem_rd_ptr;
wire read;
wire write;
reg empty;
reg next_empty;
reg full;
reg next_full;
wire [PKT_SIGNALS_WIDTH-1 : 0] in_packet_signals;
wire [PKT_SIGNALS_WIDTH-1 : 0] out_packet_signals;
wire [PAYLOAD_WIDTH-1 : 0] in_payload;
reg [PAYLOAD_WIDTH-1 : 0] internal_out_payload;
reg [PAYLOAD_WIDTH-1 : 0] out_payload;
reg internal_out_valid;
wire internal_out_ready;
reg [ADDR_WIDTH : 0] fifo_fill_level;
reg [ADDR_WIDTH : 0] fill_level;
reg [ADDR_WIDTH-1 : 0] sop_ptr = 0;
wire [ADDR_WIDTH-1 : 0] curr_sop_ptr;
reg [23:0] almost_full_threshold;
reg [23:0] almost_empty_threshold;
reg [23:0] cut_through_threshold;
reg [15:0] pkt_cnt;
reg drop_on_error_en;
reg error_in_pkt;
reg pkt_has_started;
reg sop_has_left_fifo;
reg fifo_too_small_r;
reg pkt_cnt_eq_zero;
reg pkt_cnt_eq_one;
wire wait_for_threshold;
reg pkt_mode;
wire wait_for_pkt;
wire ok_to_forward;
wire in_pkt_eop_arrive;
wire out_pkt_leave;
wire in_pkt_start;
wire in_pkt_error;
wire drop_on_error;
wire fifo_too_small;
wire out_pkt_sop_leave;
wire [31:0] max_fifo_size;
reg fifo_fill_level_lt_cut_through_threshold;
// --------------------------------------------------
// Define Payload
//
// Icky part where we decide which signals form the
// payload to the FIFO with generate blocks.
// --------------------------------------------------
generate
if (EMPTY_WIDTH > 0) begin : gen_blk1
assign in_packet_signals = {in_startofpacket, in_endofpacket, in_empty};
assign {out_startofpacket, out_endofpacket, out_empty} = out_packet_signals;
end
else begin : gen_blk1_else
assign out_empty = in_error;
assign in_packet_signals = {in_startofpacket, in_endofpacket};
assign {out_startofpacket, out_endofpacket} = out_packet_signals;
end
endgenerate
generate
if (USE_PACKETS) begin : gen_blk2
if (ERROR_WIDTH > 0) begin : gen_blk3
if (CHANNEL_WIDTH > 0) begin : gen_blk4
assign in_payload = {in_packet_signals, in_data, in_error, in_channel};
assign {out_packet_signals, out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk4_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data, in_error};
assign {out_packet_signals, out_data, out_error} = out_payload;
end
end
else begin : gen_blk3_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk5
assign in_payload = {in_packet_signals, in_data, in_channel};
assign {out_packet_signals, out_data, out_channel} = out_payload;
end
else begin : gen_blk5_else
assign out_channel = in_channel;
assign in_payload = {in_packet_signals, in_data};
assign {out_packet_signals, out_data} = out_payload;
end
end
end
else begin : gen_blk2_else
assign out_packet_signals = 0;
if (ERROR_WIDTH > 0) begin : gen_blk6
if (CHANNEL_WIDTH > 0) begin : gen_blk7
assign in_payload = {in_data, in_error, in_channel};
assign {out_data, out_error, out_channel} = out_payload;
end
else begin : gen_blk7_else
assign out_channel = in_channel;
assign in_payload = {in_data, in_error};
assign {out_data, out_error} = out_payload;
end
end
else begin : gen_blk6_else
assign out_error = in_error;
if (CHANNEL_WIDTH > 0) begin : gen_blk8
assign in_payload = {in_data, in_channel};
assign {out_data, out_channel} = out_payload;
end
else begin : gen_blk8_else
assign out_channel = in_channel;
assign in_payload = in_data;
assign out_data = out_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Memory-based FIFO storage
//
// To allow a ready latency of 0, the read index is
// obtained from the next read pointer and memory
// outputs are unregistered.
//
// If the empty latency is 1, we infer bypass logic
// around the memory so writes propagate to the
// outputs on the next cycle.
//
// Do not change the way this is coded: Quartus needs
// a perfect match to the template, and any attempt to
// refactor the two always blocks into one will break
// memory inference.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk9
if (EMPTY_LATENCY == 1) begin : gen_blk10
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] = in_payload;
internal_out_payload = mem[mem_rd_ptr];
end
end else begin : gen_blk10_else
always @(posedge clk) begin
if (in_valid && in_ready)
mem[wr_ptr] <= in_payload;
internal_out_payload <= mem[mem_rd_ptr];
end
end
assign mem_rd_ptr = next_rd_ptr;
end else begin : gen_blk9_else
// --------------------------------------------------
// Register-based FIFO storage
//
// Uses a shift register as the storage element. Each
// shift register slot has a bit which indicates if
// the slot is occupied (credit to Sam H for the idea).
// The occupancy bits are contiguous and start from the
// lsb, so 0000, 0001, 0011, 0111, 1111 for a 4-deep
// FIFO.
//
// Each slot is enabled during a read or when it
// is unoccupied. New data is always written to every
// going-to-be-empty slot (we keep track of which ones
// are actually useful with the occupancy bits). On a
// read we shift occupied slots.
//
// The exception is the last slot, which always gets
// new data when it is unoccupied.
// --------------------------------------------------
for (i = 0; i < DEPTH-1; i = i + 1) begin : shift_reg
always @(posedge clk or posedge reset) begin
if (reset) begin
mem[i] <= 0;
end
else if (read || !mem_used[i]) begin
if (!mem_used[i+1])
mem[i] <= in_payload;
else
mem[i] <= mem[i+1];
end
end
end
always @(posedge clk, posedge reset) begin
if (reset) begin
mem[DEPTH-1] <= 0;
end
else begin
if (DEPTH == 1) begin
if (write)
mem[DEPTH-1] <= in_payload;
end
else if (!mem_used[DEPTH-1])
mem[DEPTH-1] <= in_payload;
end
end
end
endgenerate
assign read = internal_out_ready && internal_out_valid && ok_to_forward;
assign write = in_ready && in_valid;
// --------------------------------------------------
// Pointer Management
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk11
assign incremented_wr_ptr = wr_ptr + 1'b1;
assign incremented_rd_ptr = rd_ptr + 1'b1;
assign next_wr_ptr = drop_on_error ? curr_sop_ptr : write ? incremented_wr_ptr : wr_ptr;
assign next_rd_ptr = (read) ? incremented_rd_ptr : rd_ptr;
always @(posedge clk or posedge reset) begin
if (reset) begin
wr_ptr <= 0;
rd_ptr <= 0;
end
else begin
wr_ptr <= next_wr_ptr;
rd_ptr <= next_rd_ptr;
end
end
end else begin : gen_blk11_else
// --------------------------------------------------
// Shift Register Occupancy Bits
//
// Consider a 4-deep FIFO with 2 entries: 0011
// On a read and write, do not modify the bits.
// On a write, left-shift the bits to get 0111.
// On a read, right-shift the bits to get 0001.
//
// Also, on a write we set bit0 (the head), while
// clearing the tail on a read.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[0] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[0] <= 1;
else if (read) begin
if (DEPTH > 1)
mem_used[0] <= mem_used[1];
else
mem_used[0] <= 0;
end
end
end
end
if (DEPTH > 1) begin : gen_blk12
always @(posedge clk or posedge reset) begin
if (reset) begin
mem_used[DEPTH-1] <= 0;
end
else begin
if (write ^ read) begin
mem_used[DEPTH-1] <= 0;
if (write)
mem_used[DEPTH-1] <= mem_used[DEPTH-2];
end
end
end
end
for (i = 1; i < DEPTH-1; i = i + 1) begin : storage_logic
always @(posedge clk, posedge reset) begin
if (reset) begin
mem_used[i] <= 0;
end
else begin
if (write ^ read) begin
if (write)
mem_used[i] <= mem_used[i-1];
else if (read)
mem_used[i] <= mem_used[i+1];
end
end
end
end
end
endgenerate
// --------------------------------------------------
// Memory FIFO Status Management
//
// Generates the full and empty signals from the
// pointers. The FIFO is full when the next write
// pointer will be equal to the read pointer after
// a write. Reading from a FIFO clears full.
//
// The FIFO is empty when the next read pointer will
// be equal to the write pointer after a read. Writing
// to a FIFO clears empty.
//
// A simultaneous read and write must not change any of
// the empty or full flags unless there is a drop on error event.
// --------------------------------------------------
generate if (USE_MEMORY_BLOCKS == 1) begin : gen_blk13
always @* begin
next_full = full;
next_empty = empty;
if (read && !write) begin
next_full = 1'b0;
if (incremented_rd_ptr == wr_ptr)
next_empty = 1'b1;
end
if (write && !read) begin
if (!drop_on_error)
next_empty = 1'b0;
else if (curr_sop_ptr == rd_ptr) // drop on error and only 1 pkt in fifo
next_empty = 1'b1;
if (incremented_wr_ptr == rd_ptr && !drop_on_error)
next_full = 1'b1;
end
if (write && read && drop_on_error) begin
if (curr_sop_ptr == next_rd_ptr)
next_empty = 1'b1;
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
empty <= 1;
full <= 0;
end
else begin
empty <= next_empty;
full <= next_full;
end
end
end else begin : gen_blk13_else
// --------------------------------------------------
// Register FIFO Status Management
//
// Full when the tail occupancy bit is 1. Empty when
// the head occupancy bit is 0.
// --------------------------------------------------
always @* begin
full = mem_used[DEPTH-1];
empty = !mem_used[0];
// ------------------------------------------
// For a single slot FIFO, reading clears the
// full status immediately.
// ------------------------------------------
if (DEPTH == 1)
full = mem_used[0] && !read;
internal_out_payload = mem[0];
// ------------------------------------------
// Writes clear empty immediately for lookahead modes.
// Note that we use in_valid instead of write to avoid
// combinational loops (in lookahead mode, qualifying
// with in_ready is meaningless).
//
// In a 1-deep FIFO, a possible combinational loop runs
// from write -> out_valid -> out_ready -> write
// ------------------------------------------
if (EMPTY_LATENCY == 0) begin
empty = !mem_used[0] && !in_valid;
if (!mem_used[0] && in_valid)
internal_out_payload = in_payload;
end
end
end
endgenerate
// --------------------------------------------------
// Avalon-ST Signals
//
// The in_ready signal is straightforward.
//
// To match memory latency when empty latency > 1,
// out_valid assertions must be delayed by one clock
// cycle.
//
// Note: out_valid deassertions must not be delayed or
// the FIFO will underflow.
// --------------------------------------------------
assign in_ready = !full;
assign internal_out_ready = out_ready || !out_valid;
generate if (EMPTY_LATENCY > 1) begin : gen_blk14
always @(posedge clk or posedge reset) begin
if (reset)
internal_out_valid <= 0;
else begin
internal_out_valid <= !empty & ok_to_forward & ~drop_on_error;
if (read) begin
if (incremented_rd_ptr == wr_ptr)
internal_out_valid <= 1'b0;
end
end
end
end else begin : gen_blk14_else
always @* begin
internal_out_valid = !empty & ok_to_forward;
end
end
endgenerate
// --------------------------------------------------
// Single Output Pipeline Stage
//
// This output pipeline stage is enabled if the FIFO's
// empty latency is set to 3 (default). It is disabled
// for all other allowed latencies.
//
// Reason: The memory outputs are unregistered, so we have to
// register the output or fmax will drop if combinatorial
// logic is present on the output datapath.
//
// Q: The Avalon-ST spec says that I have to register my outputs
// But isn't the memory counted as a register?
// A: The path from the address lookup to the memory output is
// slow. Registering the memory outputs is a good idea.
//
// The registers get packed into the memory by the fitter
// which means minimal resources are consumed (the result
// is a altsyncram with registered outputs, available on
// all modern Altera devices).
//
// This output stage acts as an extra slot in the FIFO,
// and complicates the fill level.
// --------------------------------------------------
generate if (EMPTY_LATENCY == 3) begin : gen_blk15
always @(posedge clk or posedge reset) begin
if (reset) begin
out_valid <= 0;
out_payload <= 0;
end
else begin
if (internal_out_ready) begin
out_valid <= internal_out_valid & ok_to_forward;
out_payload <= internal_out_payload;
end
end
end
end
else begin : gen_blk15_else
always @* begin
out_valid = internal_out_valid;
out_payload = internal_out_payload;
end
end
endgenerate
// --------------------------------------------------
// Fill Level
//
// The fill level is calculated from the next write
// and read pointers to avoid unnecessary latency
// and logic.
//
// However, if the store-and-forward mode of the FIFO
// is enabled, the fill level is an up-down counter
// for fmax optimization reasons.
//
// If the output pipeline is enabled, the fill level
// must account for it, or we'll always be off by one.
// This may, or may not be important depending on the
// application.
//
// For now, we'll always calculate the exact fill level
// at the cost of an extra adder when the output stage
// is enabled.
// --------------------------------------------------
generate if (USE_FILL_LEVEL) begin : gen_blk16
wire [31:0] depth32;
assign depth32 = DEPTH;
if (USE_STORE_FORWARD) begin
reg [ADDR_WIDTH : 0] curr_packet_len_less_one;
// --------------------------------------------------
// We only drop on endofpacket. As long as we don't add to the fill
// level on the dropped endofpacket cycle, we can simply subtract
// (packet length - 1) from the fill level for dropped packets.
// --------------------------------------------------
always @(posedge clk or posedge reset) begin
if (reset) begin
curr_packet_len_less_one <= 0;
end else begin
if (write) begin
curr_packet_len_less_one <= curr_packet_len_less_one + 1'b1;
if (in_endofpacket)
curr_packet_len_less_one <= 0;
end
end
end
always @(posedge clk or posedge reset) begin
if (reset) begin
fifo_fill_level <= 0;
end else if (drop_on_error) begin
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one;
if (read)
fifo_fill_level <= fifo_fill_level - curr_packet_len_less_one - 1'b1;
end else if (write && !read) begin
fifo_fill_level <= fifo_fill_level + 1'b1;
end else if (read && !write) begin
fifo_fill_level <= fifo_fill_level - 1'b1;
end
end
end else begin
always @(posedge clk or posedge reset) begin
if (reset)
fifo_fill_level <= 0;
else if (next_full & !drop_on_error)
fifo_fill_level <= depth32[ADDR_WIDTH:0];
else begin
fifo_fill_level[ADDR_WIDTH] <= 1'b0;
fifo_fill_level[ADDR_WIDTH-1 : 0] <= next_wr_ptr - next_rd_ptr;
end
end
end
always @* begin
fill_level = fifo_fill_level;
if (EMPTY_LATENCY == 3)
fill_level = fifo_fill_level + {{ADDR_WIDTH{1'b0}}, out_valid};
end
end
else begin : gen_blk16_else
always @* begin
fill_level = 0;
end
end
endgenerate
generate if (USE_ALMOST_FULL_IF) begin : gen_blk17
assign almost_full_data = (fill_level >= almost_full_threshold);
end
else
assign almost_full_data = 0;
endgenerate
generate if (USE_ALMOST_EMPTY_IF) begin : gen_blk18
assign almost_empty_data = (fill_level <= almost_empty_threshold);
end
else
assign almost_empty_data = 0;
endgenerate
// --------------------------------------------------
// Avalon-MM Status & Control Connection Point
//
// Register map:
//
// | Addr | RW | 31 - 0 |
// | 0 | R | Fill level |
//
// The registering of this connection point means
// that there is a cycle of latency between
// reads/writes and the updating of the fill level.
// --------------------------------------------------
generate if (USE_STORE_FORWARD) begin : gen_blk19
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
cut_through_threshold <= 0;
drop_on_error_en <= 0;
csr_readdata <= 0;
pkt_mode <= 1'b1;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 5)
csr_readdata <= {31'b0, drop_on_error_en};
else if (csr_address == 4)
csr_readdata <= {8'b0, cut_through_threshold};
else if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b101)
drop_on_error_en <= csr_writedata[0];
else if(csr_address == 3'b100) begin
cut_through_threshold <= csr_writedata[23:0];
pkt_mode <= (csr_writedata[23:0] == 0);
end
else if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else if (USE_ALMOST_FULL_IF || USE_ALMOST_EMPTY_IF) begin : gen_blk19_else1
assign max_fifo_size = FIFO_DEPTH - 1;
always @(posedge clk or posedge reset) begin
if (reset) begin
almost_full_threshold <= max_fifo_size[23 : 0];
almost_empty_threshold <= 0;
csr_readdata <= 0;
end
else begin
if (csr_read) begin
csr_readdata <= 32'b0;
if (csr_address == 3)
csr_readdata <= {8'b0, almost_empty_threshold};
else if (csr_address == 2)
csr_readdata <= {8'b0, almost_full_threshold};
else if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
else if (csr_write) begin
if(csr_address == 3'b011)
almost_empty_threshold <= csr_writedata[23:0];
else if(csr_address == 3'b010)
almost_full_threshold <= csr_writedata[23:0];
end
end
end
end
else begin : gen_blk19_else2
always @(posedge clk or posedge reset) begin
if (reset) begin
csr_readdata <= 0;
end
else if (csr_read) begin
csr_readdata <= 0;
if (csr_address == 0)
csr_readdata <= {{(31 - ADDR_WIDTH){1'b0}}, fill_level};
end
end
end
endgenerate
// --------------------------------------------------
// Store and forward logic
// --------------------------------------------------
// if the fifo gets full before the entire packet or the
// cut-threshold condition is met then start sending out
// data in order to avoid dead-lock situation
generate if (USE_STORE_FORWARD) begin : gen_blk20
assign wait_for_threshold = (fifo_fill_level_lt_cut_through_threshold) & wait_for_pkt ;
assign wait_for_pkt = pkt_cnt_eq_zero | (pkt_cnt_eq_one & out_pkt_leave);
assign ok_to_forward = (pkt_mode ? (~wait_for_pkt | ~pkt_has_started) :
~wait_for_threshold) | fifo_too_small_r;
assign in_pkt_eop_arrive = in_valid & in_ready & in_endofpacket;
assign in_pkt_start = in_valid & in_ready & in_startofpacket;
assign in_pkt_error = in_valid & in_ready & |in_error;
assign out_pkt_sop_leave = out_valid & out_ready & out_startofpacket;
assign out_pkt_leave = out_valid & out_ready & out_endofpacket;
assign fifo_too_small = (pkt_mode ? wait_for_pkt : wait_for_threshold) & full & out_ready;
// count packets coming and going into the fifo
always @(posedge clk or posedge reset) begin
if (reset) begin
pkt_cnt <= 0;
pkt_has_started <= 0;
sop_has_left_fifo <= 0;
fifo_too_small_r <= 0;
pkt_cnt_eq_zero <= 1'b1;
pkt_cnt_eq_one <= 1'b0;
fifo_fill_level_lt_cut_through_threshold <= 1'b1;
end
else begin
fifo_fill_level_lt_cut_through_threshold <= fifo_fill_level < cut_through_threshold;
fifo_too_small_r <= fifo_too_small;
if( in_pkt_eop_arrive )
sop_has_left_fifo <= 1'b0;
else if (out_pkt_sop_leave & pkt_cnt_eq_zero )
sop_has_left_fifo <= 1'b1;
if (in_pkt_eop_arrive & ~out_pkt_leave & ~drop_on_error ) begin
pkt_cnt <= pkt_cnt + 1'b1;
pkt_cnt_eq_zero <= 0;
if (pkt_cnt == 0)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
else if((~in_pkt_eop_arrive | drop_on_error) & out_pkt_leave) begin
pkt_cnt <= pkt_cnt - 1'b1;
if (pkt_cnt == 1)
pkt_cnt_eq_zero <= 1'b1;
else
pkt_cnt_eq_zero <= 1'b0;
if (pkt_cnt == 2)
pkt_cnt_eq_one <= 1'b1;
else
pkt_cnt_eq_one <= 1'b0;
end
if (in_pkt_start)
pkt_has_started <= 1'b1;
else if (in_pkt_eop_arrive)
pkt_has_started <= 1'b0;
end
end
// drop on error logic
always @(posedge clk or posedge reset) begin
if (reset) begin
sop_ptr <= 0;
error_in_pkt <= 0;
end
else begin
// save the location of the SOP
if ( in_pkt_start )
sop_ptr <= wr_ptr;
// remember if error in pkt
// log error only if packet has already started
if (in_pkt_eop_arrive)
error_in_pkt <= 1'b0;
else if ( in_pkt_error & (pkt_has_started | in_pkt_start))
error_in_pkt <= 1'b1;
end
end
assign drop_on_error = drop_on_error_en & (error_in_pkt | in_pkt_error) & in_pkt_eop_arrive &
~sop_has_left_fifo & ~(out_pkt_sop_leave & pkt_cnt_eq_zero);
assign curr_sop_ptr = (write && in_startofpacket && in_endofpacket) ? wr_ptr : sop_ptr;
end
else begin : gen_blk20_else
assign ok_to_forward = 1'b1;
assign drop_on_error = 1'b0;
if (ADDR_WIDTH <= 1)
assign curr_sop_ptr = 1'b0;
else
assign curr_sop_ptr = {ADDR_WIDTH - 1 { 1'b0 }};
end
endgenerate
// --------------------------------------------------
// Calculates the log2ceil of the input value
// --------------------------------------------------
function integer log2ceil;
input integer val;
reg[31:0] i;
begin
i = 1;
log2ceil = 0;
while (i < val) begin
log2ceil = log2ceil + 1;
i = i[30:0] << 1;
end
end
endfunction
endmodule
|
module axi_protocol_converter_v2_1_r_axi3_conv #
(
parameter C_FAMILY = "none",
parameter integer C_AXI_ID_WIDTH = 1,
parameter integer C_AXI_ADDR_WIDTH = 32,
parameter integer C_AXI_DATA_WIDTH = 32,
parameter integer C_AXI_SUPPORTS_USER_SIGNALS = 0,
parameter integer C_AXI_RUSER_WIDTH = 1,
parameter integer C_SUPPORT_SPLITTING = 1,
// Implement transaction splitting logic.
// Disabled whan all connected masters are AXI3 and have same or narrower data width.
parameter integer C_SUPPORT_BURSTS = 1
// Disabled when all connected masters are AxiLite,
// allowing logic to be simplified.
)
(
// System Signals
input wire ACLK,
input wire ARESET,
// Command Interface
input wire cmd_valid,
input wire cmd_split,
output wire cmd_ready,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY
);
/////////////////////////////////////////////////////////////////////////////
// Variables for generating parameter controlled instances.
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
// Constants for packing levels.
localparam [2-1:0] C_RESP_OKAY = 2'b00;
localparam [2-1:0] C_RESP_EXOKAY = 2'b01;
localparam [2-1:0] C_RESP_SLVERROR = 2'b10;
localparam [2-1:0] C_RESP_DECERR = 2'b11;
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Throttling help signals.
wire cmd_ready_i;
wire pop_si_data;
wire si_stalling;
// Internal MI-side control signals.
wire M_AXI_RREADY_I;
// Internal signals for SI-side.
wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID_I;
wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA_I;
wire [2-1:0] S_AXI_RRESP_I;
wire S_AXI_RLAST_I;
wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER_I;
wire S_AXI_RVALID_I;
wire S_AXI_RREADY_I;
/////////////////////////////////////////////////////////////////////////////
// Handle interface handshaking:
//
// Forward data from MI-Side to SI-Side while a command is available. When
// the transaction has completed the command is popped from the Command FIFO.
//
//
/////////////////////////////////////////////////////////////////////////////
// Pop word from SI-side.
assign M_AXI_RREADY_I = ~si_stalling & cmd_valid;
assign M_AXI_RREADY = M_AXI_RREADY_I;
// Indicate when there is data available @ SI-side.
assign S_AXI_RVALID_I = M_AXI_RVALID & cmd_valid;
// Get SI-side data.
assign pop_si_data = S_AXI_RVALID_I & S_AXI_RREADY_I;
// Signal that the command is done (so that it can be poped from command queue).
assign cmd_ready_i = cmd_valid & pop_si_data & M_AXI_RLAST;
assign cmd_ready = cmd_ready_i;
// Detect when MI-side is stalling.
assign si_stalling = S_AXI_RVALID_I & ~S_AXI_RREADY_I;
/////////////////////////////////////////////////////////////////////////////
// Simple AXI signal forwarding:
//
// USER, ID, DATA and RRESP passes through untouched.
//
// LAST has to be filtered to remove any intermediate LAST (due to split
// trasactions). LAST is only removed for the first parts of a split
// transaction. When splitting is unsupported is the LAST filtering completely
// completely removed.
//
/////////////////////////////////////////////////////////////////////////////
// Calculate last, i.e. mask from split transactions.
assign S_AXI_RLAST_I = M_AXI_RLAST &
( ~cmd_split | ( C_SUPPORT_SPLITTING == 0 ) );
// Data is passed through.
assign S_AXI_RID_I = M_AXI_RID;
assign S_AXI_RUSER_I = M_AXI_RUSER;
assign S_AXI_RDATA_I = M_AXI_RDATA;
assign S_AXI_RRESP_I = M_AXI_RRESP;
/////////////////////////////////////////////////////////////////////////////
// SI-side output handling
//
/////////////////////////////////////////////////////////////////////////////
// TODO: registered?
assign S_AXI_RREADY_I = S_AXI_RREADY;
assign S_AXI_RVALID = S_AXI_RVALID_I;
assign S_AXI_RID = S_AXI_RID_I;
assign S_AXI_RDATA = S_AXI_RDATA_I;
assign S_AXI_RRESP = S_AXI_RRESP_I;
assign S_AXI_RLAST = S_AXI_RLAST_I;
assign S_AXI_RUSER = S_AXI_RUSER_I;
endmodule
|
module axi_protocol_converter_v2_1_r_axi3_conv #
(
parameter C_FAMILY = "none",
parameter integer C_AXI_ID_WIDTH = 1,
parameter integer C_AXI_ADDR_WIDTH = 32,
parameter integer C_AXI_DATA_WIDTH = 32,
parameter integer C_AXI_SUPPORTS_USER_SIGNALS = 0,
parameter integer C_AXI_RUSER_WIDTH = 1,
parameter integer C_SUPPORT_SPLITTING = 1,
// Implement transaction splitting logic.
// Disabled whan all connected masters are AXI3 and have same or narrower data width.
parameter integer C_SUPPORT_BURSTS = 1
// Disabled when all connected masters are AxiLite,
// allowing logic to be simplified.
)
(
// System Signals
input wire ACLK,
input wire ARESET,
// Command Interface
input wire cmd_valid,
input wire cmd_split,
output wire cmd_ready,
// Slave Interface Read Data Ports
output wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID,
output wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA,
output wire [2-1:0] S_AXI_RRESP,
output wire S_AXI_RLAST,
output wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER,
output wire S_AXI_RVALID,
input wire S_AXI_RREADY,
// Master Interface Read Data Ports
input wire [C_AXI_ID_WIDTH-1:0] M_AXI_RID,
input wire [C_AXI_DATA_WIDTH-1:0] M_AXI_RDATA,
input wire [2-1:0] M_AXI_RRESP,
input wire M_AXI_RLAST,
input wire [C_AXI_RUSER_WIDTH-1:0] M_AXI_RUSER,
input wire M_AXI_RVALID,
output wire M_AXI_RREADY
);
/////////////////////////////////////////////////////////////////////////////
// Variables for generating parameter controlled instances.
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Local params
/////////////////////////////////////////////////////////////////////////////
// Constants for packing levels.
localparam [2-1:0] C_RESP_OKAY = 2'b00;
localparam [2-1:0] C_RESP_EXOKAY = 2'b01;
localparam [2-1:0] C_RESP_SLVERROR = 2'b10;
localparam [2-1:0] C_RESP_DECERR = 2'b11;
/////////////////////////////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Internal signals
/////////////////////////////////////////////////////////////////////////////
// Throttling help signals.
wire cmd_ready_i;
wire pop_si_data;
wire si_stalling;
// Internal MI-side control signals.
wire M_AXI_RREADY_I;
// Internal signals for SI-side.
wire [C_AXI_ID_WIDTH-1:0] S_AXI_RID_I;
wire [C_AXI_DATA_WIDTH-1:0] S_AXI_RDATA_I;
wire [2-1:0] S_AXI_RRESP_I;
wire S_AXI_RLAST_I;
wire [C_AXI_RUSER_WIDTH-1:0] S_AXI_RUSER_I;
wire S_AXI_RVALID_I;
wire S_AXI_RREADY_I;
/////////////////////////////////////////////////////////////////////////////
// Handle interface handshaking:
//
// Forward data from MI-Side to SI-Side while a command is available. When
// the transaction has completed the command is popped from the Command FIFO.
//
//
/////////////////////////////////////////////////////////////////////////////
// Pop word from SI-side.
assign M_AXI_RREADY_I = ~si_stalling & cmd_valid;
assign M_AXI_RREADY = M_AXI_RREADY_I;
// Indicate when there is data available @ SI-side.
assign S_AXI_RVALID_I = M_AXI_RVALID & cmd_valid;
// Get SI-side data.
assign pop_si_data = S_AXI_RVALID_I & S_AXI_RREADY_I;
// Signal that the command is done (so that it can be poped from command queue).
assign cmd_ready_i = cmd_valid & pop_si_data & M_AXI_RLAST;
assign cmd_ready = cmd_ready_i;
// Detect when MI-side is stalling.
assign si_stalling = S_AXI_RVALID_I & ~S_AXI_RREADY_I;
/////////////////////////////////////////////////////////////////////////////
// Simple AXI signal forwarding:
//
// USER, ID, DATA and RRESP passes through untouched.
//
// LAST has to be filtered to remove any intermediate LAST (due to split
// trasactions). LAST is only removed for the first parts of a split
// transaction. When splitting is unsupported is the LAST filtering completely
// completely removed.
//
/////////////////////////////////////////////////////////////////////////////
// Calculate last, i.e. mask from split transactions.
assign S_AXI_RLAST_I = M_AXI_RLAST &
( ~cmd_split | ( C_SUPPORT_SPLITTING == 0 ) );
// Data is passed through.
assign S_AXI_RID_I = M_AXI_RID;
assign S_AXI_RUSER_I = M_AXI_RUSER;
assign S_AXI_RDATA_I = M_AXI_RDATA;
assign S_AXI_RRESP_I = M_AXI_RRESP;
/////////////////////////////////////////////////////////////////////////////
// SI-side output handling
//
/////////////////////////////////////////////////////////////////////////////
// TODO: registered?
assign S_AXI_RREADY_I = S_AXI_RREADY;
assign S_AXI_RVALID = S_AXI_RVALID_I;
assign S_AXI_RID = S_AXI_RID_I;
assign S_AXI_RDATA = S_AXI_RDATA_I;
assign S_AXI_RRESP = S_AXI_RRESP_I;
assign S_AXI_RLAST = S_AXI_RLAST_I;
assign S_AXI_RUSER = S_AXI_RUSER_I;
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
|
module e1 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
endmodule
|
module ch (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = z ^ (x & (y ^ z));
endmodule
|
module maj (x, y, z, o);
input [31:0] x, y, z;
output [31:0] o;
assign o = (x & y) | (z & (x | y));
endmodule
|
module s0 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:29] = x[6:4] ^ x[17:15];
assign y[28:0] = {x[3:0], x[31:7]} ^ {x[14:0],x[31:18]} ^ x[31:3];
endmodule
|
module s1 (x, y);
input [31:0] x;
output [31:0] y;
assign y[31:22] = x[16:7] ^ x[18:9];
assign y[21:0] = {x[6:0],x[31:17]} ^ {x[8:0],x[31:19]} ^ x[31:10];
endmodule
|
module e0 (x, y);
input [31:0] x;
output [31:0] y;
assign y = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
endmodule
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