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-rw-r--r--src/hash.cpp69
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