Multiple AVLs with bloom filters (very raw test version)

src/MurmurHash2.c

@@ -0,0 +1,64 @@
+//-----------------------------------------------------------------------------
+// MurmurHash2, by Austin Appleby
+
+// Note - This code makes a few assumptions about how your machine behaves -
+
+// 1. We can read a 4-byte value from any address without crashing
+// 2. sizeof(int) == 4
+
+// And it has a few limitations -
+
+// 1. It will not work incrementally.
+// 2. It will not produce the same results on little-endian and big-endian
+//    machines.
+
+unsigned int murmurhash2(const void * key, int len, const unsigned int seed)
+{
+	// 'm' and 'r' are mixing constants generated offline.
+	// They're not really 'magic', they just happen to work well.
+
+	const unsigned int m = 0x5bd1e995;
+	const int r = 24;
+
+	// Initialize the hash to a 'random' value
+
+	unsigned int h = seed ^ len;
+
+	// Mix 4 bytes at a time into the hash
+
+	const unsigned char * data = (const unsigned char *)key;
+
+	while(len >= 4)
+	{
+		unsigned int k = *(unsigned int *)data;
+
+		k *= m;
+		k ^= k >> r;
+		k *= m;
+
+		h *= m;
+		h ^= k;
+
+		data += 4;
+		len -= 4;
+	}
+
+	// Handle the last few bytes of the input array
+
+	switch(len)
+	{
+	case 3: h ^= data[2] << 16;
+	case 2: h ^= data[1] << 8;
+	case 1: h ^= data[0];
+	        h *= m;
+	};
+
+	// Do a few final mixes of the hash to ensure the last few
+	// bytes are well-incorporated.
+
+	h ^= h >> 13;
+	h *= m;
+	h ^= h >> 15;
+
+	return h;
+}