You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
59 lines
1.3 KiB
59 lines
1.3 KiB
12 years ago
|
#include "hash.h"
|
||
|
|
|
||
|
|
inline uint32_t ROTL32 ( uint32_t x, int8_t r )
|
||
|
|
{
|
||
|
|
return (x << r) | (x >> (32 - r));
|
||
|
|
}
|
||
|
|
|
||
|
|
unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char>& vDataToHash)
|
||
|
|
{
|
||
|
|
// The following is MurmurHash3 (x86_32), see http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp
|
||
|
|
uint32_t h1 = nHashSeed;
|
||
|
|
const uint32_t c1 = 0xcc9e2d51;
|
||
|
|
const uint32_t c2 = 0x1b873593;
|
||
|
|
|
||
|
|
const int nblocks = vDataToHash.size() / 4;
|
||
|
|
|
||
|
|
//----------
|
||
|
|
// body
|
||
|
|
const uint32_t * blocks = (const uint32_t *)(&vDataToHash[0] + nblocks*4);
|
||
|
|
|
||
|
|
for(int i = -nblocks; i; i++)
|
||
|
|
{
|
||
|
|
uint32_t k1 = 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*)(&vDataToHash[0] + nblocks*4);
|
||
|
|
|
||
|
|
uint32_t k1 = 0;
|
||
|
|
|
||
|
|
switch(vDataToHash.size() & 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 ^= vDataToHash.size();
|
||
|
|
h1 ^= h1 >> 16;
|
||
|
|
h1 *= 0x85ebca6b;
|
||
|
|
h1 ^= h1 >> 13;
|
||
|
|
h1 *= 0xc2b2ae35;
|
||
|
|
h1 ^= h1 >> 16;
|
||
|
|
|
||
|
|
return h1;
|
||
|
|
}
|