public override ECPoint Twice()
{
if (this.IsInfinity)
{
return(this);
}
ECCurve curve = this.Curve;
SecP256K1FieldElement Y1 = (SecP256K1FieldElement)this.RawYCoord;
if (Y1.IsZero)
{
return(curve.Infinity);
}
SecP256K1FieldElement X1 = (SecP256K1FieldElement)this.RawXCoord, Z1 = (SecP256K1FieldElement)this.RawZCoords[0];
uint c;
uint[] Y1Squared = Nat256.Create();
SecP256K1Field.Square(Y1.x, Y1Squared);
uint[] T = Nat256.Create();
SecP256K1Field.Square(Y1Squared, T);
uint[] M = Nat256.Create();
SecP256K1Field.Square(X1.x, M);
c = Nat256.AddBothTo(M, M, M);
SecP256K1Field.Reduce32(c, M);
uint[] S = Y1Squared;
SecP256K1Field.Multiply(Y1Squared, X1.x, S);
c = Nat.ShiftUpBits(8, S, 2, 0);
SecP256K1Field.Reduce32(c, S);
uint[] t1 = Nat256.Create();
c = Nat.ShiftUpBits(8, T, 3, 0, t1);
SecP256K1Field.Reduce32(c, t1);
SecP256K1FieldElement X3 = new SecP256K1FieldElement(T);
SecP256K1Field.Square(M, X3.x);
SecP256K1Field.Subtract(X3.x, S, X3.x);
SecP256K1Field.Subtract(X3.x, S, X3.x);
SecP256K1FieldElement Y3 = new SecP256K1FieldElement(S);
SecP256K1Field.Subtract(S, X3.x, Y3.x);
SecP256K1Field.Multiply(Y3.x, M, Y3.x);
SecP256K1Field.Subtract(Y3.x, t1, Y3.x);
SecP256K1FieldElement Z3 = new SecP256K1FieldElement(M);
SecP256K1Field.Twice(Y1.x, Z3.x);
if (!Z1.IsOne)
{
SecP256K1Field.Multiply(Z3.x, Z1.x, Z3.x);
}
return(new SecP256K1Point(curve, X3, Y3, new ECFieldElement[] { Z3 }, IsCompressed));
}
