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#ifndef MURMUR3_H
#define MURMUR3_H
//-----------------------------------------------------------------------------
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.
// Note - The x86 and x64 versions do _not_ produce the same results, as the
// algorithms are optimized for their respective platforms. You can still
// compile and run any of them on any platform, but your performance with the
// non-native version will be less than optimal.
//-----------------------------------------------------------------------------
// Platform-specific functions and macros
// Microsoft Visual Studio
#if defined(_MSC_VER)
#define FORCE_INLINE __forceinline
typedef unsigned char uint8_t;
typedef unsigned long uint32_t;
typedef unsigned __int64 uint64_t;
// Other compilers
#else // defined(_MSC_VER)
#include <stdint.h>
#endif // !defined(_MSC_VER)
#define FORCE_INLINE inline __attribute__((always_inline))
inline uint32_t rotl32(uint32_t x, int8_t r) {
return (x << r) | (x >> (32 - r));
}
#define BIG_CONSTANT(x) (x##LLU)
/* NO-OP for little-endian platforms */
#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__)
# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define BYTESWAP(x) (x)
# endif
/* if __BYTE_ORDER__ is not predefined (like FreeBSD), use arch */
#elif defined(__i386) || defined(__x86_64) \
|| defined(__alpha) || defined(__vax)
# define BYTESWAP(x) (x)
/* use __builtin_bswap32 if available */
#elif defined(__GNUC__) || defined(__clang__)
#ifdef __has_builtin
#if __has_builtin(__builtin_bswap32)
#define BYTESWAP(x) __builtin_bswap32(x)
#endif // __has_builtin(__builtin_bswap32)
#endif // __has_builtin
#endif // defined(__GNUC__) || defined(__clang__)
/* last resort (big-endian w/o __builtin_bswap) */
#ifndef BYTESWAP
# define BYTESWAP(x) ((((x)&0xFF)<<24) \
|(((x)>>24)&0xFF) \
|(((x)&0x0000FF00)<<8) \
|(((x)&0x00FF0000)>>8) )
#endif
//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here
#define getblock(p, i) BYTESWAP(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;
}
//-----------------------------------------------------------------------------
#ifdef __cplusplus
extern "C"
#else
extern
#endif
void MurmurHash3_32(const void * key, int len, uint32_t seed, void * out) {
const uint8_t * data = (const uint8_t*) key;
const int nblocks = len / 4;
int i;
uint32_t h1 = seed;
uint32_t c1 = 0xcc9e2d51;
uint32_t c2 = 0x1b873593;
//----------
// body
const uint32_t * blocks = (const uint32_t *) (data + nblocks * 4);
for (i = -nblocks; i; i++) {
uint32_t k1 = getblock(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);
*(uint32_t*) out = h1;
}
#endif
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