创建

client/nirvana_murmurhash.cpp

@@ -0,0 +1,99 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "nirvana_murmurhash.h"
+
+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;
+		default:break;
+	};
+
+	// 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;
+}
+
+/*64-bit hash for 64-bit platforms*/
+u_int64_t MurmurHash64A(const void * key, int len, unsigned int seed)
+{
+	const uint64_t m = 0xc6a4a7935bd1e995;
+	const int r = 47;
+	uint64_t k, h = seed ^ (len * m);
+	const uint64_t * data = (const uint64_t *)key;
+	const uint64_t * end = data + (len/8);
+
+	while (data != end)
+	{
+		k = *data++;
+		k *= m;
+		k ^= k >> r;
+		k *= m;
+
+		h ^= k;
+		h *= m;
+	}
+
+	const unsigned char * data2 = (const unsigned char*)data;
+
+	switch (len & 7)
+	{
+		case 7: h ^= uint64_t(data2[6]) << 48;
+		case 6: h ^= uint64_t(data2[5]) << 40;
+		case 5: h ^= uint64_t(data2[4]) << 32;
+		case 4: h ^= uint64_t(data2[3]) << 24;
+		case 3: h ^= uint64_t(data2[2]) << 16;
+		case 2: h ^= uint64_t(data2[1]) << 8;
+		case 1: h ^= uint64_t(data2[0]);
+		h *= m;
+	};
+
+	h ^= h >> r;
+	h *= m;
+	h ^= h >> r;
+
+	return h;
+}
+
+