LBRYCommunity/lbrycrd
1
0
Fork 0
Code Issues 29 Pull requests 1 Projects Releases 32 Packages Wiki Activity

Avoiding referencing elements of an empty vector

Browse source
This commit is contained in:
ENikS 2014-09-23 11:54:12 -04:00
parent 35ee2dac67
commit 459a2d25e0
1 changed files with 36 additions and 33 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

69
src/hash.cpp
View file

@ -9,46 +9,49 @@ 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;
const uint32_t c1 = 0xcc9e2d51; if (vDataToHash.size() > 0)
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 uint32_t* blocks = (const uint32_t*)(&vDataToHash[0] + nblocks * 4); const uint32_t* blocks = (const uint32_t*)(&vDataToHash[0] + nblocks * 4);
for (int i = -nblocks; i; i++) { for (int i = -nblocks; i; i++) {
uint32_t k1 = blocks[i]; uint32_t k1 = blocks[i];
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
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 // finalization
h1 ^= vDataToHash.size(); h1 ^= vDataToHash.size();