{
    "modulus"          : "2^255-19",
    "base"             : "51",
    "a24"              : "121665",
    "sz"               : "5",
    "bitwidth"         : "64",
    "carry_chains"     : "default",
    "coef_div_modulus" : "2",
    "operations"       : ["femul", "feadd", "fesub", "fecarry", "fesquare", "freeze", "ladderstep"],
    "extra_files"      : ["X25519_C64/scalarmult.c"],
    "compiler"         : "gcc -march=native -mbmi2 -mtune=native -std=gnu11 -O3 -flto -fomit-frame-pointer -fwrapv -Wno-attributes",
    "mul_header"       : "(* Micro-optimized form from curve25519-donna-c64 by Adam Langley (Google) and Daniel Bernstein. See <https://github.com/agl/curve25519-donna/blob/master/LICENSE.md>. *)",
    "mul_code"
    :
    "
  uint128_t t[5];
  limb r0,r1,r2,r3,r4,s0,s1,s2,s3,s4,c;

  r0 = in[0];
  r1 = in[1];
  r2 = in[2];
  r3 = in[3];
  r4 = in[4];

  s0 = in2[0];
  s1 = in2[1];
  s2 = in2[2];
  s3 = in2[3];
  s4 = in2[4];

  t[0]  =  ((uint128_t) r0) * s0;
  t[1]  =  ((uint128_t) r0) * s1 + ((uint128_t) r1) * s0;
  t[2]  =  ((uint128_t) r0) * s2 + ((uint128_t) r2) * s0 + ((uint128_t) r1) * s1;
  t[3]  =  ((uint128_t) r0) * s3 + ((uint128_t) r3) * s0 + ((uint128_t) r1) * s2 + ((uint128_t) r2) * s1;
  t[4]  =  ((uint128_t) r0) * s4 + ((uint128_t) r4) * s0 + ((uint128_t) r3) * s1 + ((uint128_t) r1) * s3 + ((uint128_t) r2) * s2;

  r4 *= 19;
  r1 *= 19;
  r2 *= 19;
  r3 *= 19;

  t[0] += ((uint128_t) r4) * s1 + ((uint128_t) r1) * s4 + ((uint128_t) r2) * s3 + ((uint128_t) r3) * s2;
  t[1] += ((uint128_t) r4) * s2 + ((uint128_t) r2) * s4 + ((uint128_t) r3) * s3;
  t[2] += ((uint128_t) r4) * s3 + ((uint128_t) r3) * s4;
  t[3] += ((uint128_t) r4) * s4;
",
    "square_header"    : "(* Micro-optimized form from curve25519-donna-c64 by Adam Langley (Google) and Daniel Bernstein. See <https://github.com/agl/curve25519-donna/blob/master/LICENSE.md>. *)",
    "square_code"
    :
    "
  uint128_t t[5];
  limb r0,r1,r2,r3,r4,c;
  limb d0,d1,d2,d4,d419;

  r0 = in[0];
  r1 = in[1];
  r2 = in[2];
  r3 = in[3];
  r4 = in[4];

  do {
    d0 = r0 * 2;
    d1 = r1 * 2;
    d2 = r2 * 2 * 19;
    d419 = r4 * 19;
    d4 = d419 * 2;

    t[0] = ((uint128_t) r0) * r0 + ((uint128_t) d4) * r1 + (((uint128_t) d2) * (r3     ));
    t[1] = ((uint128_t) d0) * r1 + ((uint128_t) d4) * r2 + (((uint128_t) r3) * (r3 * 19));
    t[2] = ((uint128_t) d0) * r2 + ((uint128_t) r1) * r1 + (((uint128_t) d4) * (r3     ));
    t[3] = ((uint128_t) d0) * r3 + ((uint128_t) d1) * r2 + (((uint128_t) r4) * (d419   ));
    t[4] = ((uint128_t) d0) * r4 + ((uint128_t) d1) * r3 + (((uint128_t) r2) * (r2     ));
"
}