hash.c


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#include <stdint.h>
#include <stdlib.h>
#include "hash.h"

//-----------------------------------------------------------------------------
// MurmurHashNeutral2, by Austin Appleby

// Same as MurmurHash2, but endian- and alignment-neutral.
uint32_t hash_murmur2(const void * key, int len)
{
	const unsigned int seed = 0xdeadc0de;
	const unsigned int m = 0x5bd1e995;
	const int r = 24;

	unsigned int h = seed ^ len;

	const unsigned char * data = (const unsigned char *)key;

	while(len >= 4)
	{
		unsigned int k;

		k  = data[0];
		k |= data[1] << 8;
		k |= data[2] << 16;
		k |= data[3] << 24;

		k *= m;
		k ^= k >> r;
		k *= m;

		h *= m;
		h ^= k;

		data += 4;
		len -= 4;
	}

	switch(len)
	{
	case 3: h ^= data[2] << 16;
	case 2: h ^= data[1] << 8;
	case 1: h ^= data[0];
	        h *= m;
	};

	h ^= h >> 13;
	h *= m;
	h ^= h >> 15;

	return h;
}