diff --git a/src/util/hash.c b/src/util/hash.c new file mode 100644 index 000000000..96e2ffb7f --- /dev/null +++ b/src/util/hash.c @@ -0,0 +1,99 @@ +// MurmurHash3 was written by Austin Appleby, and is placed in the public +// domain. The author hereby disclaims copyright to this source code. + +#include "hash.h" + +#if defined(_MSC_VER) + +#define FORCE_INLINE __forceinline + +#include + +#define ROTL32(x,y) _rotl(x,y) + +#else + +#define FORCE_INLINE inline __attribute__((always_inline)) + +static inline uint32_t rotl32 ( uint32_t x, int8_t r ) { + return (x << r) | (x >> (32 - r)); +} + +#define ROTL32(x,y) rotl32(x,y) + +#endif + +//----------------------------------------------------------------------------- +// Block read - if your platform needs to do endian-swapping or can only +// handle aligned reads, do the conversion here + +static FORCE_INLINE uint32_t getblock32 ( const uint32_t * p, int i ) { + return p[i]; +} + +//----------------------------------------------------------------------------- +// Finalization mix - force all bits of a hash block to avalanche + +static FORCE_INLINE uint32_t fmix32 (uint32_t h) { + h ^= h >> 16; + h *= 0x85ebca6b; + h ^= h >> 13; + h *= 0xc2b2ae35; + h ^= h >> 16; + + return h; +} + +//----------------------------------------------------------------------------- + +uint32_t hash32(const void* key, int len, uint32_t seed) { + const uint8_t * data = (const uint8_t*)key; + const int nblocks = len / 4; + + uint32_t h1 = seed; + + const uint32_t c1 = 0xcc9e2d51; + const uint32_t c2 = 0x1b873593; + + //---------- + // body + + const uint32_t * blocks = (const uint32_t *)(data + nblocks*4); + + for(int i = -nblocks; i; i++) + { + uint32_t k1 = getblock32(blocks,i); + + k1 *= c1; + k1 = ROTL32(k1,15); + k1 *= c2; + + h1 ^= k1; + h1 = ROTL32(h1,13); + h1 = h1*5+0xe6546b64; + } + + //---------- + // tail + + const uint8_t * tail = (const uint8_t*)(data + nblocks*4); + + uint32_t k1 = 0; + + switch(len & 3) + { + case 3: k1 ^= tail[2] << 16; + case 2: k1 ^= tail[1] << 8; + case 1: k1 ^= tail[0]; + k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1; + }; + + //---------- + // finalization + + h1 ^= len; + + h1 = fmix32(h1); + + return h1; +} diff --git a/src/util/hash.h b/src/util/hash.h new file mode 100644 index 000000000..825d3e152 --- /dev/null +++ b/src/util/hash.h @@ -0,0 +1,8 @@ +#ifndef HASH_H +#define HASH_H + +#include "util/common.h" + +uint32_t hash32(const void* key, int len, uint32_t seed); + +#endif