public static FourierPoint operator >>(FourierPoint x, int shift)
{
ulong[] number = new ulong[2] {
x.Low, x.High
};
while (shift >= 64)
{
ulong carry = AsmX64Operations.MultiplyDigitAndAdd(PrimeModuloDigits, NegativeInverseLowP * number[0], number, 2);
number[0] = number[1];
number[1] = carry;
shift -= 64;
}
if (shift != 0)
{
ulong mask = (1UL << shift) - 1UL;
ulong carry = AsmX64Operations.MultiplyDigitAndAdd(PrimeModuloDigits, NegativeInverseLowP * number[0] & mask, number, 2);
return(new FourierPoint((number[0] >> shift) | (number[1] << (64 - shift)), (number[1] >> shift) | (carry << (64 - shift))));
}
return(new FourierPoint(number[0], number[1]));
}
//return: P * factor on the elliptic curves domain.
public OwnECPoint Multiply(OwnECPoint p, ulong[] factor)
{
ulong[] exp = new ulong[factor.Length + 1];
ulong[] exp3 = new ulong[factor.Length + 1];
factor.CopyTo(exp, 0);
exp3[factor.Length] = AsmX64Operations.MultiplyDigitAndAdd(exp, 3, exp3, factor.Length);
for (int i = exp.Length; --i >= 0;)
{
exp3[i] ^= exp[i]; //exp3= (exp*3) ^ exp
}
int high = HighBit(exp3);
if (high < 0)
{
return(new OwnECPoint(p.X, p.Y, true));
}
JacobianECPoint x = new JacobianECPoint(p.X, p.Y, true);
ulong mask = 1UL << (high & 63);
for (int i = high; --i >= 0;)
{
GetDouble(ref x);
if ((exp3[(i + 1) >> 6] & mask) != 0)
{
if ((exp[(i + 1) >> 6] & mask) != 0)
{
Subtract(ref x, p);
}
else
{
Add(ref x, p);
}
}
mask = (mask >> 1) | (mask << 63);
}
OwnECPoint result = x.ToECPoint(this);
return(result);
}
