134 lines
3.0 KiB
C
134 lines
3.0 KiB
C
//-----------------------------------------------------------------------------
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// MurmurHash3 was written by Austin Appleby, and is placed in the public
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// domain. The author hereby disclaims copyright to this source code.
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// Note - The x86 and x64 versions do _not_ produce the same results, as the
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// algorithms are optimized for their respective platforms. You can still
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// compile and run any of them on any platform, but your performance with the
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// non-native version will be less than optimal.
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#include "murmur3.h"
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//-----------------------------------------------------------------------------
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#ifdef _MSC_FULL_VER
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#define FORCE_INLINE static
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#else
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#define FORCE_INLINE inline __attribute__((always_inline))
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#endif
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inline uint32_t rotl32 ( uint32_t x, int8_t r )
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{
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return (x << r) | (x >> (32 - r));
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}
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inline uint64_t rotl64 ( uint64_t x, int8_t r )
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{
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return (x << r) | (x >> (64 - r));
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}
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#define ROTL32(x,y)rotl32(x,y)
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#define ROTL64(x,y)rotl64(x,y)
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#define BIG_CONSTANT(x) (x##LLU)
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//-----------------------------------------------------------------------------
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// Block read - if your platform needs to do endian-swapping or can only
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// handle aligned reads, do the conversion here
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FORCE_INLINE uint32_t getblock32 ( const uint32_t * p, int i )
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{
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return p[i];
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}
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FORCE_INLINE uint64_t getblock64 ( const uint64_t * p, int i )
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{
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return p[i];
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}
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//-----------------------------------------------------------------------------
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// Finalization mix - force all bits of a hash block to avalanche
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FORCE_INLINE uint32_t fmix32 ( uint32_t h )
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{
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h ^= h >> 16;
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h *= 0x85ebca6b;
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h ^= h >> 13;
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h *= 0xc2b2ae35;
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h ^= h >> 16;
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return h;
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}
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//----------
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FORCE_INLINE uint64_t fmix64 ( uint64_t k )
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{
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k ^= k >> 33;
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k *= BIG_CONSTANT(0xff51afd7ed558ccd);
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k ^= k >> 33;
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k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
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k ^= k >> 33;
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return k;
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}
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//-----------------------------------------------------------------------------
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void MurmurHash3_x86_32 ( const void * key, int len,
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uint32_t seed, void * out )
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{
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const uint8_t * data = (const uint8_t*)key;
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const int nblocks = len / 4;
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uint32_t h1 = seed;
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const uint32_t c1 = 0xcc9e2d51;
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const uint32_t c2 = 0x1b873593;
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//----------
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// body
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const uint32_t * blocks = (const uint32_t *)(data + nblocks*4);
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for(int i = -nblocks; i; i++)
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{
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uint32_t k1 = getblock32(blocks,i);
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k1 *= c1;
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k1 = ROTL32(k1,15);
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k1 *= c2;
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h1 ^= k1;
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h1 = ROTL32(h1,13);
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h1 = h1*5+0xe6546b64;
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}
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//----------
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// tail
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const uint8_t * tail = (const uint8_t*)(data + nblocks*4);
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uint32_t k1 = 0;
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switch(len & 3)
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{
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case 3: k1 ^= tail[2] << 16; /* fall-through */
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case 2: k1 ^= tail[1] << 8; /* fall-through */
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case 1: k1 ^= tail[0];
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k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1;
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};
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//----------
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// finalization
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h1 ^= len;
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h1 = fmix32(h1);
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*(uint32_t*)out = h1;
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}
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//-----------------------------------------------------------------------------
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