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/* This is the Murmur3 hash algorithm.
*
* MurmurHash3 was written by Austin Appleby, and is placed in the public
* domain. The author hereby disclaims copyright to this source code.
*/
#include <stdint.h>
#include <stdio.h>
#define FORCE_INLINE static 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)
/* Block read - if your platform needs to do endian-swapping or can
only handle aligned reads, do the conversion here. */
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. */
FORCE_INLINE uint32_t fmix32 ( uint32_t h )
{
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
/* The Murmur3 hash function. */
static uint32_t
MurmurHash3_x86_32 (const void *key, size_t len, uint32_t seed)
{
const uint8_t * data = (const uint8_t*)key;
const int nblocks = (int) (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;
}
uint32_t hurd_ihash_hash32 (const void *, size_t, uint32_t)
__attribute__ ((weak, alias ("MurmurHash3_x86_32")));
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