[geodisambig] adding MurmurHash3, used by the Bloom filter

src/murmur/murmur.c

@@ -0,0 +1,118 @@
+//-----------------------------------------------------------------------------
+// MurmurHash3 was written by Austin Appleby, and is placed in the public
+// domain. The author hereby disclaims copyright to this source code.
+
+// Note - The x86 and x64 versions do _not_ produce the same results, as the
+// algorithms are optimized for their respective platforms. You can still
+// compile and run any of them on any platform, but your performance with the
+// non-native version will be less than optimal.
+
+#include "murmur.h"
+
+#define FORCE_INLINE inline static
+
+FORCE_INLINE uint64_t rotl64 ( uint64_t x, int8_t r )
+{
+    return (x << r) | (x >> (64 - r));
+}
+
+#define ROTL64(x,y) rotl64(x,y)
+
+#define BIG_CONSTANT(x) (x##LLU)
+
+#define getblock(x, i) (x[i])
+
+//-----------------------------------------------------------------------------
+// Finalization mix - force all bits of a hash block to avalanche
+
+FORCE_INLINE uint64_t fmix64(uint64_t k)
+{
+    k ^= k >> 33;
+    k *= BIG_CONSTANT(0xff51afd7ed558ccd);
+    k ^= k >> 33;
+    k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
+    k ^= k >> 33;
+
+    return k;
+}
+
+//-----------------------------------------------------------------------------
+
+void MurmurHash3_x64_128 ( const void * key, const int len,
+        const uint32_t seed, void * out )
+{
+    const uint8_t * data = (const uint8_t*)key;
+    const int nblocks = len / 16;
+
+    uint64_t h1 = seed;
+    uint64_t h2 = seed;
+
+    uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
+    uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);
+
+    int i;
+
+    //----------
+    // body
+
+    const uint64_t * blocks = (const uint64_t *)(data);
+
+    for(i = 0; i < nblocks; i++) {
+        uint64_t k1 = getblock(blocks,i*2+0);
+        uint64_t k2 = getblock(blocks,i*2+1);
+
+        k1 *= c1; k1  = ROTL64(k1,31); k1 *= c2; h1 ^= k1;
+
+        h1 = ROTL64(h1,27); h1 += h2; h1 = h1*5+0x52dce729;
+
+        k2 *= c2; k2  = ROTL64(k2,33); k2 *= c1; h2 ^= k2;
+
+        h2 = ROTL64(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
+    }
+
+    //----------
+    // tail
+
+    const uint8_t * tail = (const uint8_t*)(data + nblocks*16);
+
+    uint64_t k1 = 0;
+    uint64_t k2 = 0;
+
+    switch(len & 15) {
+        case 15: k2 ^= ((uint64_t)tail[14]) << 48;
+        case 14: k2 ^= ((uint64_t)tail[13]) << 40;
+        case 13: k2 ^= ((uint64_t)tail[12]) << 32;
+        case 12: k2 ^= ((uint64_t)tail[11]) << 24;
+        case 11: k2 ^= ((uint64_t)tail[10]) << 16;
+        case 10: k2 ^= ((uint64_t)tail[ 9]) << 8;
+        case  9: k2 ^= ((uint64_t)tail[ 8]) << 0;
+                 k2 *= c2; k2  = ROTL64(k2,33); k2 *= c1; h2 ^= k2;
+
+        case  8: k1 ^= ((uint64_t)tail[ 7]) << 56;
+        case  7: k1 ^= ((uint64_t)tail[ 6]) << 48;
+        case  6: k1 ^= ((uint64_t)tail[ 5]) << 40;
+        case  5: k1 ^= ((uint64_t)tail[ 4]) << 32;
+        case  4: k1 ^= ((uint64_t)tail[ 3]) << 24;
+        case  3: k1 ^= ((uint64_t)tail[ 2]) << 16;
+        case  2: k1 ^= ((uint64_t)tail[ 1]) << 8;
+        case  1: k1 ^= ((uint64_t)tail[ 0]) << 0;
+                 k1 *= c1; k1  = ROTL64(k1,31); k1 *= c2; h1 ^= k1;
+    }
+
+    //----------
+    // finalization
+
+    h1 ^= len; h2 ^= len;
+
+    h1 += h2;
+    h2 += h1;
+
+    h1 = fmix64(h1);
+    h2 = fmix64(h2);
+
+    h1 += h2;
+    h2 += h1;
+
+    ((uint64_t*)out)[0] = h1;
+    ((uint64_t*)out)[1] = h2;
+}

src/murmur/murmur.h

@@ -0,0 +1,12 @@
+//-----------------------------------------------------------------------------
+// MurmurHash3 was written by Austin Appleby, and is placed in the public
+// domain. The author hereby disclaims copyright to this source code.
+
+#ifndef _MURMURHASH3_H_
+#define _MURMURHASH3_H_
+
+#include <stdint.h>
+
+void MurmurHash3_x64_128 ( const void * key, int len, uint32_t seed, void * out );
+
+#endif // _MURMURHASH3_H_