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152 lines
3.7 KiB
C++
152 lines
3.7 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 "MurmurHash3.h"
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#include <cstring>
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//-----------------------------------------------------------------------------
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// Platform-specific functions and macros
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// Microsoft Visual Studio
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#if defined(_MSC_VER)
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#define FORCE_INLINE __forceinline
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#include <stdlib.h>
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#define ROTL64(x,y) _rotl64(x,y)
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#define BIG_CONSTANT(x) (x)
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// Other compilers
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#else // defined(_MSC_VER)
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#define FORCE_INLINE inline __attribute__((always_inline))
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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 ROTL64(x,y) rotl64(x,y)
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#define BIG_CONSTANT(x) (x##LLU)
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#endif // !defined(_MSC_VER)
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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 uint64_t getblock64 ( const uint64_t * p, int i )
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{
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uint64_t result = 0;
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std::memcpy(&result, p + i, sizeof(result));
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return result;
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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_x64_128 ( const void * key, const int len,
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const uint64_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 / 16;
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uint64_t h1 = seed[0];
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uint64_t h2 = seed[1];
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const uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
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const uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
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//----------
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// body
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const uint64_t * blocks = (const uint64_t *)(data);
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for(int i = 0; i < nblocks; i++)
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{
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uint64_t k1 = getblock64(blocks,i*2+0);
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uint64_t k2 = getblock64(blocks,i*2+1);
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k1 *= c1; k1 = ROTL64(k1,31); k1 *= c2; h1 ^= k1;
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h1 = ROTL64(h1,27); h1 += h2; h1 = h1*5+0x52dce729;
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k2 *= c2; k2 = ROTL64(k2,33); k2 *= c1; h2 ^= k2;
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h2 = ROTL64(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
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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*16);
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uint64_t k1 = 0;
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uint64_t k2 = 0;
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switch(len & 15)
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{
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case 15: k2 ^= ((uint64_t)tail[14]) << 48;
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case 14: k2 ^= ((uint64_t)tail[13]) << 40;
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case 13: k2 ^= ((uint64_t)tail[12]) << 32;
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case 12: k2 ^= ((uint64_t)tail[11]) << 24;
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case 11: k2 ^= ((uint64_t)tail[10]) << 16;
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case 10: k2 ^= ((uint64_t)tail[ 9]) << 8;
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case 9: k2 ^= ((uint64_t)tail[ 8]) << 0;
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k2 *= c2; k2 = ROTL64(k2,33); k2 *= c1; h2 ^= k2;
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case 8: k1 ^= ((uint64_t)tail[ 7]) << 56;
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case 7: k1 ^= ((uint64_t)tail[ 6]) << 48;
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case 6: k1 ^= ((uint64_t)tail[ 5]) << 40;
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case 5: k1 ^= ((uint64_t)tail[ 4]) << 32;
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case 4: k1 ^= ((uint64_t)tail[ 3]) << 24;
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case 3: k1 ^= ((uint64_t)tail[ 2]) << 16;
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case 2: k1 ^= ((uint64_t)tail[ 1]) << 8;
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case 1: k1 ^= ((uint64_t)tail[ 0]) << 0;
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k1 *= c1; k1 = ROTL64(k1,31); k1 *= c2; h1 ^= k1;
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};
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//----------
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// finalization
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h1 ^= len; h2 ^= len;
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h1 += h2;
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h2 += h1;
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h1 = fmix64(h1);
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h2 = fmix64(h2);
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h1 += h2;
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h2 += h1;
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((uint64_t*)out)[0] = h1;
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((uint64_t*)out)[1] = h2;
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}
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//-----------------------------------------------------------------------------
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