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-rw-r--r--src/hash.cpp58
1 files changed, 58 insertions, 0 deletions
diff --git a/src/hash.cpp b/src/hash.cpp
new file mode 100644
index 0000000000..bddd8abf38
--- /dev/null
+++ b/src/hash.cpp
@@ -0,0 +1,58 @@
+#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;
+}