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#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);
}
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