+++ /dev/null
-/*
- "Murmur" hash provided by Austin, tanjent@gmail.com
- http://murmurhash.googlepages.com/
-
- 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.
-
- Updated to murmur2 hash - BP
-*/
-
-#include <libhashkit/common.h>
-
-uint32_t hashkit_murmur(const char *key, size_t length, void *context)
-{
- /*
- '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 uint32_t seed= (0xdeadbeef * (uint32_t)length);
- const int r= 24;
-
-
- // Initialize the hash to a 'random' value
-
- uint32_t h= seed ^ (uint32_t)length;
-
- // Mix 4 bytes at a time into the hash
-
- const unsigned char * data= (const unsigned char *)key;
- (void)context;
-
- while(length >= 4)
- {
- unsigned int k = *(unsigned int *)data;
-
- k *= m;
- k ^= k >> r;
- k *= m;
-
- h *= m;
- h ^= k;
-
- data += 4;
- length -= 4;
- }
-
- // Handle the last few bytes of the input array
-
- switch(length)
- {
- case 3: h ^= ((uint32_t)data[2]) << 16;
- case 2: h ^= ((uint32_t)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;
-}