| #include "murmur3.h" |
| |
| static inline uint32_t rotl32(uint32_t x, int8_t r) |
| { |
| return (x << r) | (x >> (32 - r)); |
| } |
| |
| //----------------------------------------------------------------------------- |
| // Finalization mix - force all bits of a hash block to avalanche |
| |
| static inline uint32_t fmix32(uint32_t h) |
| { |
| h ^= h >> 16; |
| h *= 0x85ebca6b; |
| h ^= h >> 13; |
| h *= 0xc2b2ae35; |
| h ^= h >> 16; |
| |
| return h; |
| } |
| |
| static uint32_t murmur3_tail(const uint8_t *data, const int nblocks, |
| uint32_t len, const uint32_t c1, |
| const uint32_t c2, uint32_t h1) |
| { |
| 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; |
| }; |
| |
| return fmix32(h1 ^ len); |
| } |
| |
| uint32_t murmurhash3(const void *key, uint32_t 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; |
| const uint32_t *blocks = (const uint32_t *)(data + nblocks * 4); |
| int i; |
| |
| for (i = -nblocks; i; i++) { |
| uint32_t k1 = blocks[i]; |
| |
| k1 *= c1; |
| k1 = rotl32(k1, 15); |
| k1 *= c2; |
| |
| h1 ^= k1; |
| h1 = rotl32(h1, 13); |
| h1 = h1 * 5 + 0xe6546b64; |
| } |
| |
| return murmur3_tail(data, nblocks, len, c1, c2, h1); |
| } |