private static void Marvin32Mix(ref Marvin32State state, uint value)
{
state.Lo += value;
state.Hi ^= state.Lo;
state.Lo = RotateLeft(state.Lo, 20) + state.Hi;
state.Hi = RotateLeft(state.Hi, 09) ^ state.Lo;
state.Lo = RotateLeft(state.Lo, 27) + state.Hi;
state.Hi = RotateLeft(state.Hi, 19);
}
private static int GetMarvin32HashCore(string str, int startIndex, int length, ulong seed)
{
// NB: This code is adapted from the CoreCLR hash code in https://github.com/dotnet/coreclr/blob/master/src/vm/marvin32.cpp
// and is patented by Microsoft (US 20130262421 A1).
var state = new Marvin32State
{
Lo = (uint)(seed),
Hi = (uint)(seed >> 32)
};
var len = length;
for (var i = startIndex; len >= 2; i += 2, len -= 2)
{
Marvin32Mix(ref state, TwoInt16ToInt32LittleEndian(str, i));
}
uint final = 0x80;
if (len != 0)
{
Debug.Assert(len == 1);
var c = (uint)str[length - 1];
var b1 = c & 0x00FF;
var b2 = c >> 8;
final = (final << 8) | b1;
final = (final << 8) | b2;
}
Marvin32Mix(ref state, final);
Marvin32Mix(ref state, 0);
return(unchecked ((int)(state.Lo ^ state.Hi)));
}
