printf, uprintf, tprintf -- formatted output conversion
printf(const char *fmt, ...);
tprintf(struct proc *p, int pri, const char *fmt, ...);
uprintf(const char *fmt, ...);
The printf(9) family of functions are similar to the printf(3) family of
functions. The three functions each use a different output stream. The
uprintf() function outputs to the current process' controlling tty, while
printf() writes to the console as well as to the logging facility. The
tprintf() function outputs to the tty associated with the process p and
the logging facility if pri is not -1.
Each of these related functions use the fmt parameter in the same manner
as printf(3). However, printf(9) adds two other conversion specifiers.
The %b identifier expects two arguments: an int and a char *. These are
used as a register value and a print mask for decoding bitmasks. The
print mask is made up of two parts: the base and the arguments. The base
value is the output base expressed as an integer value; for example, \10
gives octal and \20 gives hexadecimal. The arguments are made up of a
sequence of bit identifiers. Each bit identifier begins with an integer
value which is the number of the bit this identifier describes. The rest
of the identifier is a string of characters containing the name of the
bit. The string is terminated by either the bit number at the start of
the next bit identifier or NUL for the last bit identifier.
The %D identifier is meant to assist in hexdumps. It requires two arguments:
a u_char * pointer and a char * string. The memory pointed to be
the pointer is output in hexadecimal one byte at a time. The string is
used as a delimiter between individual bytes. If present, a width directive
will specify the number of bytes to display. By default, 16 bytes
of data are output.
The printf() and the uprintf() functions return the number of characters
This example demonstrates the use of the %b and %D conversion specifiers.
printf("reg=%b\n", 3, "\10\2BITTWO\1BITONE\n");
printf("out: %4D\n", "AAAA", ":");
will produce the following output:
FreeBSD 5.2.1 April 25, 2001 FreeBSD 5.2.1 [ Back ]