class Ed25519FieldElement implements Serializable {

  public Ed25519FieldElement multiply(final Ed25519FieldElement g) {
    final int[] gValues = g.values;
    final int f0 = this.values[0];
    final int f1 = this.values[1];
    final int f2 = this.values[2];
    final int f3 = this.values[3];
    final int f4 = this.values[4];
    final int f5 = this.values[5];
    final int f6 = this.values[6];
    final int f7 = this.values[7];
    final int f8 = this.values[8];
    final int f9 = this.values[9];
    final int g0 = gValues[0];
    final int g1 = gValues[1];
    final int g2 = gValues[2];
    final int g3 = gValues[3];
    final int g4 = gValues[4];
    final int g5 = gValues[5];
    final int g6 = gValues[6];
    final int g7 = gValues[7];
    final int g8 = gValues[8];
    final int g9 = gValues[9];
    final int g1_19 = 19 * g1; /* 1.959375*2^29 */
    final int g2_19 = 19 * g2; /* 1.959375*2^30; still ok */
    final int g3_19 = 19 * g3;
    final int g4_19 = 19 * g4;
    final int g5_19 = 19 * g5;
    final int g6_19 = 19 * g6;
    final int g7_19 = 19 * g7;
    final int g8_19 = 19 * g8;
    final int g9_19 = 19 * g9;
    final int f1_2 = 2 * f1;
    final int f3_2 = 2 * f3;
    final int f5_2 = 2 * f5;
    final int f7_2 = 2 * f7;
    final int f9_2 = 2 * f9;
    final long f0g0 = f0 * (long) g0;
    final long f0g1 = f0 * (long) g1;
    final long f0g2 = f0 * (long) g2;
    final long f0g3 = f0 * (long) g3;
    final long f0g4 = f0 * (long) g4;
    final long f0g5 = f0 * (long) g5;
    final long f0g6 = f0 * (long) g6;
    final long f0g7 = f0 * (long) g7;
    final long f0g8 = f0 * (long) g8;
    final long f0g9 = f0 * (long) g9;
    final long f1g0 = f1 * (long) g0;
    final long f1g1_2 = f1_2 * (long) g1;
    final long f1g2 = f1 * (long) g2;
    final long f1g3_2 = f1_2 * (long) g3;
    final long f1g4 = f1 * (long) g4;
    final long f1g5_2 = f1_2 * (long) g5;
    final long f1g6 = f1 * (long) g6;
    final long f1g7_2 = f1_2 * (long) g7;
    final long f1g8 = f1 * (long) g8;
    final long f1g9_38 = f1_2 * (long) g9_19;
    final long f2g0 = f2 * (long) g0;
    final long f2g1 = f2 * (long) g1;
    final long f2g2 = f2 * (long) g2;
    final long f2g3 = f2 * (long) g3;
    final long f2g4 = f2 * (long) g4;
    final long f2g5 = f2 * (long) g5;
    final long f2g6 = f2 * (long) g6;
    final long f2g7 = f2 * (long) g7;
    final long f2g8_19 = f2 * (long) g8_19;
    final long f2g9_19 = f2 * (long) g9_19;
    final long f3g0 = f3 * (long) g0;
    final long f3g1_2 = f3_2 * (long) g1;
    final long f3g2 = f3 * (long) g2;
    final long f3g3_2 = f3_2 * (long) g3;
    final long f3g4 = f3 * (long) g4;
    final long f3g5_2 = f3_2 * (long) g5;
    final long f3g6 = f3 * (long) g6;
    final long f3g7_38 = f3_2 * (long) g7_19;
    final long f3g8_19 = f3 * (long) g8_19;
    final long f3g9_38 = f3_2 * (long) g9_19;
    final long f4g0 = f4 * (long) g0;
    final long f4g1 = f4 * (long) g1;
    final long f4g2 = f4 * (long) g2;
    final long f4g3 = f4 * (long) g3;
    final long f4g4 = f4 * (long) g4;
    final long f4g5 = f4 * (long) g5;
    final long f4g6_19 = f4 * (long) g6_19;
    final long f4g7_19 = f4 * (long) g7_19;
    final long f4g8_19 = f4 * (long) g8_19;
    final long f4g9_19 = f4 * (long) g9_19;
    final long f5g0 = f5 * (long) g0;
    final long f5g1_2 = f5_2 * (long) g1;
    final long f5g2 = f5 * (long) g2;
    final long f5g3_2 = f5_2 * (long) g3;
    final long f5g4 = f5 * (long) g4;
    final long f5g5_38 = f5_2 * (long) g5_19;
    final long f5g6_19 = f5 * (long) g6_19;
    final long f5g7_38 = f5_2 * (long) g7_19;
    final long f5g8_19 = f5 * (long) g8_19;
    final long f5g9_38 = f5_2 * (long) g9_19;
    final long f6g0 = f6 * (long) g0;
    final long f6g1 = f6 * (long) g1;
    final long f6g2 = f6 * (long) g2;
    final long f6g3 = f6 * (long) g3;
    final long f6g4_19 = f6 * (long) g4_19;
    final long f6g5_19 = f6 * (long) g5_19;
    final long f6g6_19 = f6 * (long) g6_19;
    final long f6g7_19 = f6 * (long) g7_19;
    final long f6g8_19 = f6 * (long) g8_19;
    final long f6g9_19 = f6 * (long) g9_19;
    final long f7g0 = f7 * (long) g0;
    final long f7g1_2 = f7_2 * (long) g1;
    final long f7g2 = f7 * (long) g2;
    final long f7g3_38 = f7_2 * (long) g3_19;
    final long f7g4_19 = f7 * (long) g4_19;
    final long f7g5_38 = f7_2 * (long) g5_19;
    final long f7g6_19 = f7 * (long) g6_19;
    final long f7g7_38 = f7_2 * (long) g7_19;
    final long f7g8_19 = f7 * (long) g8_19;
    final long f7g9_38 = f7_2 * (long) g9_19;
    final long f8g0 = f8 * (long) g0;
    final long f8g1 = f8 * (long) g1;
    final long f8g2_19 = f8 * (long) g2_19;
    final long f8g3_19 = f8 * (long) g3_19;
    final long f8g4_19 = f8 * (long) g4_19;
    final long f8g5_19 = f8 * (long) g5_19;
    final long f8g6_19 = f8 * (long) g6_19;
    final long f8g7_19 = f8 * (long) g7_19;
    final long f8g8_19 = f8 * (long) g8_19;
    final long f8g9_19 = f8 * (long) g9_19;
    final long f9g0 = f9 * (long) g0;
    final long f9g1_38 = f9_2 * (long) g1_19;
    final long f9g2_19 = f9 * (long) g2_19;
    final long f9g3_38 = f9_2 * (long) g3_19;
    final long f9g4_19 = f9 * (long) g4_19;
    final long f9g5_38 = f9_2 * (long) g5_19;
    final long f9g6_19 = f9 * (long) g6_19;
    final long f9g7_38 = f9_2 * (long) g7_19;
    final long f9g8_19 = f9 * (long) g8_19;
    final long f9g9_38 = f9_2 * (long) g9_19;

    /**
     * Remember: 2^255 congruent 19 modulo p. h = h0 * 2^0 + h1 * 2^26 + h2 * 2^(26+25) + h3 *
     * 2^(26+25+26) + ... + h9 * 2^(5*26+5*25). So to get the real number we would have to multiply
     * the coefficients with the corresponding powers of 2. To get an idea what is going on below,
     * look at the calculation of h0: h0 is the coefficient to the power 2^0 so it collects (sums)
     * all products that have the power 2^0. f0 * g0 really is f0 * 2^0 * g0 * 2^0 = (f0 * g0) *
     * 2^0. f1 * g9 really is f1 * 2^26 * g9 * 2^230 = f1 * g9 * 2^256 = 2 * f1 * g9 * 2^255
     * congruent 2 * 19 * f1 * g9 * 2^0 modulo p. f2 * g8 really is f2 * 2^51 * g8 * 2^204 = f2 * g8
     * * 2^255 congruent 19 * f2 * g8 * 2^0 modulo p. and so on...
     */
    long h0 =
        f0g0 + f1g9_38 + f2g8_19 + f3g7_38 + f4g6_19 + f5g5_38 + f6g4_19 + f7g3_38 + f8g2_19
            + f9g1_38;
    long h1 =
        f0g1 + f1g0 + f2g9_19 + f3g8_19 + f4g7_19 + f5g6_19 + f6g5_19 + f7g4_19 + f8g3_19 + f9g2_19;
    long h2 =
        f0g2 + f1g1_2 + f2g0 + f3g9_38 + f4g8_19 + f5g7_38 + f6g6_19 + f7g5_38 + f8g4_19 + f9g3_38;
    long h3 = f0g3 + f1g2 + f2g1 + f3g0 + f4g9_19 + f5g8_19 + f6g7_19 + f7g6_19 + f8g5_19 + f9g4_19;
    long h4 =
        f0g4 + f1g3_2 + f2g2 + f3g1_2 + f4g0 + f5g9_38 + f6g8_19 + f7g7_38 + f8g6_19 + f9g5_38;
    long h5 = f0g5 + f1g4 + f2g3 + f3g2 + f4g1 + f5g0 + f6g9_19 + f7g8_19 + f8g7_19 + f9g6_19;
    long h6 = f0g6 + f1g5_2 + f2g4 + f3g3_2 + f4g2 + f5g1_2 + f6g0 + f7g9_38 + f8g8_19 + f9g7_38;
    long h7 = f0g7 + f1g6 + f2g5 + f3g4 + f4g3 + f5g2 + f6g1 + f7g0 + f8g9_19 + f9g8_19;
    long h8 = f0g8 + f1g7_2 + f2g6 + f3g5_2 + f4g4 + f5g3_2 + f6g2 + f7g1_2 + f8g0 + f9g9_38;
    long h9 = f0g9 + f1g8 + f2g7 + f3g6 + f4g5 + f5g4 + f6g3 + f7g2 + f8g1 + f9g0;
    long carry0;
    final long carry1;
    final long carry2;
    final long carry3;
    long carry4;
    final long carry5;
    final long carry6;
    final long carry7;
    final long carry8;
    final long carry9;

    /**
     * |h0| <= (1.65*1.65*2^52*(1+19+19+19+19)+1.65*1.65*2^50*(38+38+38+38+38)) i.e. |h0| <=
     * 1.4*2^60; narrower ranges for h2, h4, h6, h8 |h1| <=
     * (1.65*1.65*2^51*(1+1+19+19+19+19+19+19+19+19)) i.e. |h1| <= 1.7*2^59; narrower ranges for h3,
     * h5, h7, h9
     */
    carry0 = (h0 + (long) (1 << 25)) >> 26;
    h1 += carry0;
    h0 -= carry0 << 26;
    carry4 = (h4 + (long) (1 << 25)) >> 26;
    h5 += carry4;
    h4 -= carry4 << 26;
    /* |h0| <= 2^25 */
    /* |h4| <= 2^25 */
    /* |h1| <= 1.71*2^59 */
    /* |h5| <= 1.71*2^59 */

    carry1 = (h1 + (long) (1 << 24)) >> 25;
    h2 += carry1;
    h1 -= carry1 << 25;
    carry5 = (h5 + (long) (1 << 24)) >> 25;
    h6 += carry5;
    h5 -= carry5 << 25;
    /* |h1| <= 2^24; from now on fits into int32 */
    /* |h5| <= 2^24; from now on fits into int32 */
    /* |h2| <= 1.41*2^60 */
    /* |h6| <= 1.41*2^60 */

    carry2 = (h2 + (long) (1 << 25)) >> 26;
    h3 += carry2;
    h2 -= carry2 << 26;
    carry6 = (h6 + (long) (1 << 25)) >> 26;
    h7 += carry6;
    h6 -= carry6 << 26;
    /* |h2| <= 2^25; from now on fits into int32 unchanged */
    /* |h6| <= 2^25; from now on fits into int32 unchanged */
    /* |h3| <= 1.71*2^59 */
    /* |h7| <= 1.71*2^59 */

    carry3 = (h3 + (long) (1 << 24)) >> 25;
    h4 += carry3;
    h3 -= carry3 << 25;
    carry7 = (h7 + (long) (1 << 24)) >> 25;
    h8 += carry7;
    h7 -= carry7 << 25;
    /* |h3| <= 2^24; from now on fits into int32 unchanged */
    /* |h7| <= 2^24; from now on fits into int32 unchanged */
    /* |h4| <= 1.72*2^34 */
    /* |h8| <= 1.41*2^60 */

    carry4 = (h4 + (long) (1 << 25)) >> 26;
    h5 += carry4;
    h4 -= carry4 << 26;
    carry8 = (h8 + (long) (1 << 25)) >> 26;
    h9 += carry8;
    h8 -= carry8 << 26;
    /* |h4| <= 2^25; from now on fits into int32 unchanged */
    /* |h8| <= 2^25; from now on fits into int32 unchanged */
    /* |h5| <= 1.01*2^24 */
    /* |h9| <= 1.71*2^59 */

    carry9 = (h9 + (long) (1 << 24)) >> 25;
    h0 += carry9 * 19;
    h9 -= carry9 << 25;
    /* |h9| <= 2^24; from now on fits into int32 unchanged */
    /* |h0| <= 1.1*2^39 */

    carry0 = (h0 + (long) (1 << 25)) >> 26;
    h1 += carry0;
    h0 -= carry0 << 26;
    /* |h0| <= 2^25; from now on fits into int32 unchanged */
    /* |h1| <= 1.01*2^24 */

    final int[] h = new int[10];
    h[0] = (int) h0;
    h[1] = (int) h1;
    h[2] = (int) h2;
    h[3] = (int) h3;
    h[4] = (int) h4;
    h[5] = (int) h5;
    h[6] = (int) h6;
    h[7] = (int) h7;
    h[8] = (int) h8;
    h[9] = (int) h9;

    return new Ed25519FieldElement(h);
  }

  public  Ed25519FieldElement(final int[] values);

}