/// <summary>
/// Returns the MurmurHash3_x86_32 hash.
/// Original source/tests at <a href="https://github.com/yonik/java_util/">https://github.com/yonik/java_util/</a>.
/// </summary>
public static int Murmurhash3_x86_32(byte[] data, int offset, int len, int seed)
{
const int c1 = unchecked ((int)0xcc9e2d51);
const int c2 = 0x1b873593;
int h1 = seed;
int roundedEnd = offset + (len & unchecked ((int)0xfffffffc)); // round down to 4 byte block
for (int i = offset; i < roundedEnd; i += 4)
{
// little endian load order
int k1 = (((sbyte)data[i]) & 0xff) | ((((sbyte)data[i + 1]) & 0xff) << 8) | ((((sbyte)data[i + 2]) & 0xff) << 16) | (((sbyte)data[i + 3]) << 24);
k1 *= c1;
k1 = Number.RotateLeft(k1, 15);
k1 *= c2;
h1 ^= k1;
h1 = Number.RotateLeft(h1, 13);
h1 = h1 * 5 + unchecked ((int)0xe6546b64);
}
// tail
int k2 = 0;
switch (len & 0x03)
{
case 3:
k2 = (((sbyte)data[roundedEnd + 2]) & 0xff) << 16;
// fallthrough
goto case 2;
case 2:
k2 |= (((sbyte)data[roundedEnd + 1]) & 0xff) << 8;
// fallthrough
goto case 1;
case 1:
k2 |= (((sbyte)data[roundedEnd]) & 0xff);
k2 *= c1;
k2 = Number.RotateLeft(k2, 15);
k2 *= c2;
h1 ^= k2;
break;
}
// finalization
h1 ^= len;
// fmix(h1);
h1 ^= (int)((uint)h1 >> 16);
h1 *= unchecked ((int)0x85ebca6b);
h1 ^= (int)((uint)h1 >> 13);
h1 *= unchecked ((int)0xc2b2ae35);
h1 ^= (int)((uint)h1 >> 16);
return(h1);
}
public override int GetHashCode()
{
int h = base.GetHashCode();
h = Number.RotateLeft(h, 1);
h ^= include.GetHashCode();
h = Number.RotateLeft(h, 1);
h ^= exclude.GetHashCode();
h = Number.RotateLeft(h, 1);
h ^= pre;
h = Number.RotateLeft(h, 1);
h ^= post;
return(h);
}
