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/*-----------------------------------------------------------------------------
* MurmurHash2, by Austin Appleby
*
* Note - This code makes a few assumptions about how your machine behaves -
*
* 1. We can read a 4-byte value from any address without crashing
* 2. sizeof(int) == 4
*
* And it has a few limitations -
*
* 1. It will not work incrementally.
* 2. It will not produce the same results on little-endian and big-endian
* machines.
*/
unsigned int murmurhash2 ( const void * key, int len, unsigned int seed )
{
/* 'm' and 'r' are mixing constants generated offline.
* They're not really 'magic', they just happen to work well.
*/
const unsigned int m = 0x5bd1e995;
const int r = 24;
/* Initialize the hash to a 'random' value */
unsigned int h = seed ^ len;
/* Mix 4 bytes at a time into the hash */
const unsigned char * data = (const unsigned char *)key;
while(len >= 4)
{
unsigned int k = *(unsigned int *)data;
k *= m;
k ^= k >> r;
k *= m;
h *= m;
h ^= k;
data += 4;
len -= 4;
}
/* Handle the last few bytes of the input array */
switch(len)
{
case 3: h ^= data[2] << 16;
case 2: h ^= data[1] << 8;
case 1: h ^= data[0];
h *= m;
};
/* Do a few final mixes of the hash to ensure the last few
* bytes are well-incorporated.
*/
h ^= h >> 13;
h *= m;
h ^= h >> 15;
return h;
}