Cleanup (safe, it was checked) subscript[0] in MurmurHash3 (and cleanup MurmurHash3 to be more clear).
This commit is contained in:
parent
96f2119e6c
commit
6896dbf169
1 changed files with 20 additions and 23 deletions
43
src/hash.cpp
43
src/hash.cpp
|
@ -17,36 +17,34 @@ 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
|
// The following is MurmurHash3 (x86_32), see http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp
|
||||||
uint32_t h1 = nHashSeed;
|
uint32_t h1 = nHashSeed;
|
||||||
if (vDataToHash.size() > 0)
|
const uint32_t c1 = 0xcc9e2d51;
|
||||||
{
|
const uint32_t c2 = 0x1b873593;
|
||||||
const uint32_t c1 = 0xcc9e2d51;
|
|
||||||
const uint32_t c2 = 0x1b873593;
|
|
||||||
|
|
||||||
const int nblocks = vDataToHash.size() / 4;
|
const int nblocks = vDataToHash.size() / 4;
|
||||||
|
|
||||||
//----------
|
//----------
|
||||||
// body
|
// body
|
||||||
const uint8_t* blocks = &vDataToHash[0] + nblocks * 4;
|
const uint8_t* blocks = vDataToHash.data();
|
||||||
|
|
||||||
for (int i = -nblocks; i; i++) {
|
for (int i = 0; i < nblocks; ++i) {
|
||||||
uint32_t k1 = ReadLE32(blocks + i*4);
|
uint32_t k1 = ReadLE32(blocks + i*4);
|
||||||
|
|
||||||
k1 *= c1;
|
k1 *= c1;
|
||||||
k1 = ROTL32(k1, 15);
|
k1 = ROTL32(k1, 15);
|
||||||
k1 *= c2;
|
k1 *= c2;
|
||||||
|
|
||||||
h1 ^= k1;
|
h1 ^= k1;
|
||||||
h1 = ROTL32(h1, 13);
|
h1 = ROTL32(h1, 13);
|
||||||
h1 = h1 * 5 + 0xe6546b64;
|
h1 = h1 * 5 + 0xe6546b64;
|
||||||
}
|
}
|
||||||
|
|
||||||
//----------
|
//----------
|
||||||
// tail
|
// tail
|
||||||
const uint8_t* tail = (const uint8_t*)(&vDataToHash[0] + nblocks * 4);
|
const uint8_t* tail = vDataToHash.data() + nblocks * 4;
|
||||||
|
|
||||||
uint32_t k1 = 0;
|
uint32_t k1 = 0;
|
||||||
|
|
||||||
switch (vDataToHash.size() & 3) {
|
switch (vDataToHash.size() & 3) {
|
||||||
case 3:
|
case 3:
|
||||||
k1 ^= tail[2] << 16;
|
k1 ^= tail[2] << 16;
|
||||||
case 2:
|
case 2:
|
||||||
|
@ -57,7 +55,6 @@ unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char
|
||||||
k1 = ROTL32(k1, 15);
|
k1 = ROTL32(k1, 15);
|
||||||
k1 *= c2;
|
k1 *= c2;
|
||||||
h1 ^= k1;
|
h1 ^= k1;
|
||||||
}
|
|
||||||
}
|
}
|
||||||
|
|
||||||
//----------
|
//----------
|
||||||
|
|
Loading…
Reference in a new issue