100 lines
1.8 KiB
C++
100 lines
1.8 KiB
C++
#include <stdint.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include "nirvana_murmurhash.h"
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unsigned int murmurhash2(const void * key, int len, const unsigned int seed)
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{
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// 'm' and 'r' are mixing constants generated offline.
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// They're not really 'magic', they just happen to work well.
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const unsigned int m = 0x5bd1e995;
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const int r = 24;
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// Initialize the hash to a 'random' value
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unsigned int h = seed ^ len;
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// Mix 4 bytes at a time into the hash
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const unsigned char * data = (const unsigned char *)key;
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while(len >= 4)
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{
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unsigned int k = *(unsigned int *)data;
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k *= m;
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k ^= k >> r;
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k *= m;
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h *= m;
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h ^= k;
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data += 4;
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len -= 4;
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}
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// Handle the last few bytes of the input array
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switch(len)
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{
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case 3: h ^= data[2] << 16;
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case 2: h ^= data[1] << 8;
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case 1: h ^= data[0];
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h *= m;
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default:break;
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};
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// Do a few final mixes of the hash to ensure the last few
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// bytes are well-incorporated.
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h ^= h >> 13;
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h *= m;
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h ^= h >> 15;
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return h;
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}
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/*64-bit hash for 64-bit platforms*/
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u_int64_t MurmurHash64A(const void * key, int len, unsigned int seed)
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{
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const uint64_t m = 0xc6a4a7935bd1e995;
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const int r = 47;
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uint64_t k, h = seed ^ (len * m);
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const uint64_t * data = (const uint64_t *)key;
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const uint64_t * end = data + (len/8);
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while (data != end)
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{
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k = *data++;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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}
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const unsigned char * data2 = (const unsigned char*)data;
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switch (len & 7)
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{
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case 7: h ^= uint64_t(data2[6]) << 48;
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case 6: h ^= uint64_t(data2[5]) << 40;
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case 5: h ^= uint64_t(data2[4]) << 32;
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case 4: h ^= uint64_t(data2[3]) << 24;
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case 3: h ^= uint64_t(data2[2]) << 16;
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case 2: h ^= uint64_t(data2[1]) << 8;
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case 1: h ^= uint64_t(data2[0]);
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h *= m;
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};
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h ^= h >> r;
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h *= m;
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h ^= h >> r;
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return h;
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}
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