//nb: Constructing two new Int128 objects every time we want to multiply longs
//is slow. So, although calling the Int128Mul method doesn't look as clean, the
//code runs significantly faster than if we'd used the * operator.
public static ClipperInt128 Int128Mul(long lhs, long rhs)
{
bool negate = (lhs < 0) != (rhs < 0);
if (lhs < 0)
{
lhs = -lhs;
}
if (rhs < 0)
{
rhs = -rhs;
}
ulong int1Hi = (ulong)lhs >> 32;
ulong int1Lo = (ulong)lhs & 0xFFFFFFFF;
ulong int2Hi = (ulong)rhs >> 32;
ulong int2Lo = (ulong)rhs & 0xFFFFFFFF;
//nb: see comments in clipper.pas
ulong a = int1Hi * int2Hi;
ulong b = int1Lo * int2Lo;
ulong c = int1Hi * int2Lo + int1Lo * int2Hi;
ulong lo;
long hi;
hi = (long)(a + (c >> 32));
unchecked { lo = (c << 32) + b; }
if (lo < b)
{
hi++;
}
ClipperInt128 result = new ClipperInt128(hi, lo);
return(negate ? -result : result);
}
public ClipperInt128(ClipperInt128 val)
{
hi = val.hi;
lo = val.lo;
}
