/*

  *  MurmurHash.c

  *  MYUtilities

  *

  *  This file created by Jens Alfke on 3/17/08.

  *  Algorithm & source code by Austin Appleby, released to public domain.

  *  <http://murmurhash.googlepages.com/>

  *  Downloaded 3/16/2008.

  *  Modified slightly by Jens Alfke (use standard uint32_t and size_t types;

  *  change 'm' and 'r' to #defines for better C compatibility.)

  *

  */

 #include "MurmurHash.h"

 //-----------------------------------------------------------------------------

 // 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      **Jens: I fixed this by changing 'unsigned int' to 'uint32_t'**

 // 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.

 uint32_t MurmurHash2 ( const void * key, size_t len, uint32_t seed )

 {

     // 'm' and 'r' are mixing constants generated offline.

     // They're not really 'magic', they just happen to work well.

     #define m 0x5bd1e995

     #define r 24

     // Initialize the hash to a 'random' value

     uint32_t h = seed ^ len;

     // Mix 4 bytes at a time into the hash

     const unsigned char * data = (const unsigned char *)key;

     while(len >= 4)

     {

         uint32_t k = *(uint32_t *)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;

 }