secp256k1GejAddVar static method

Implementation

static void secp256k1GejAddVar(
    Secp256k1Gej r, Secp256k1Gej a, Secp256k1Gej b, Secp256k1Fe? rzr) {
  /// 12 mul, 4 sqr, 11 add/negate/normalizes_to_zero (ignoring special cases)
  Secp256k1Fe z22 = Secp256k1Fe(),
      z12 = Secp256k1Fe(),
      u1 = Secp256k1Fe(),
      u2 = Secp256k1Fe(),
      s1 = Secp256k1Fe(),
      s2 = Secp256k1Fe(),
      h = Secp256k1Fe(),
      i = Secp256k1Fe(),
      h2 = Secp256k1Fe(),
      h3 = Secp256k1Fe(),
      t = Secp256k1Fe();
  if (a.infinity.toBool) {
    _cond(rzr == null, "secp256k1GejAddVar");
    r.set(b);
    return;
  }
  if (b.infinity.toBool) {
    if (rzr != null) {
      secp256k1FeSetInt(rzr, 1);
    }
    r.set(a);
    return;
  }

  secp256k1FeSqr(z22, b.z);
  secp256k1FeSqr(z12, a.z);
  secp256k1FeMul(u1, a.x, z22);
  secp256k1FeMul(u2, b.x, z12);
  secp256k1FeMul(s1, a.y, z22);
  secp256k1FeMul(s1, s1, b.z);
  secp256k1FeMul(s2, b.y, z12);
  secp256k1FeMul(s2, s2, a.z);
  secp256k1FeNegate(h, u1, 1);
  secp256k1FeAdd(h, u2);
  secp256k1FeNegate(i, s2, 1);
  secp256k1FeAdd(i, s1);
  if (secp256k1FeNormalizesToZeroVar(h).toBool) {
    if (secp256k1FeNormalizesToZeroVar(i).toBool) {
      secp256k1GejDoubleVar(r, a, rzr);
    } else {
      if (rzr != null) {
        secp256k1FeSetInt(rzr, 0);
      }
      secp256k1GejSetInfinity(r);
    }
    return;
  }

  r.infinity = 0;
  secp256k1FeMul(t, h, b.z);
  if (rzr != null) {
    rzr.set(t);
  }
  secp256k1FeMul(r.z, a.z, t);

  secp256k1FeSqr(h2, h);
  secp256k1FeNegate(h2, h2, 1);
  secp256k1FeMul(h3, h2, h);
  secp256k1FeMul(t, u1, h2);

  secp256k1FeSqr(r.x, i);
  secp256k1FeAdd(r.x, h3);
  secp256k1FeAdd(r.x, t);
  secp256k1FeAdd(r.x, t);

  secp256k1FeAdd(t, r.x);
  secp256k1FeMul(r.y, t, i);
  secp256k1FeMul(h3, h3, s1);
  secp256k1FeAdd(r.y, h3);
}