diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/hash.cpp | 69 |
1 files changed, 36 insertions, 33 deletions
diff --git a/src/hash.cpp b/src/hash.cpp index 4ce4da4c30..218607a6fd 100644 --- a/src/hash.cpp +++ b/src/hash.cpp @@ -9,45 +9,48 @@ unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char { // 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; + if (vDataToHash.size() > 0) + { + const uint32_t c1 = 0xcc9e2d51; + const uint32_t c2 = 0x1b873593; - const int nblocks = vDataToHash.size() / 4; + const int nblocks = vDataToHash.size() / 4; - //---------- - // body - const uint32_t* blocks = (const uint32_t*)(&vDataToHash[0] + nblocks * 4); + //---------- + // body + const uint32_t* blocks = (const uint32_t*)(&vDataToHash[0] + nblocks * 4); - for (int i = -nblocks; i; i++) { - uint32_t k1 = blocks[i]; + for (int i = -nblocks; i; i++) { + uint32_t k1 = blocks[i]; - k1 *= c1; - k1 = ROTL32(k1, 15); - k1 *= c2; + k1 *= c1; + k1 = ROTL32(k1, 15); + k1 *= c2; - h1 ^= k1; - h1 = ROTL32(h1, 13); - h1 = h1 * 5 + 0xe6546b64; - } + 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; - }; + //---------- + // 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 |