Question

I need to Hash a NSString using murmurhash i am forced to do that because the other team is doing so, I need to use the 64-bit key length on x86 platform, have anyone implemented or used murmurhash in objective-C?

Murmurhash 64 is a .cpp file and i can’t get it compiled in iOS SDK 4.3, also tried to rename it to .mm but the result still the same.

Any help or Guide would be greatly appreciated.

I will post the Compilation Error Messages if someone is interested.

Answer 1

For all those who will come to look for the correct answer, here is the deal:

MurmurHash64.h class
careful I have changed the typedef

// MurmurHash, by Austin Appleby

typedef unsigned long long uint64_t;

uint64_t MurmurHash64B ( const void * key, int len, unsigned int seed );

MurmurHash64.m class

#include "MurmurHash64.h"
// 64-bit hash for 32-bit platforms

uint64_t MurmurHash64B ( const void * key, int len, unsigned int seed )
{
    const unsigned int m = 0x5bd1e995;
    const int r = 24;

    unsigned int h1 = seed ^ len;
    unsigned int h2 = 0;

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

    while(len >= 8)
    {
       unsigned int k1 = *data++;
       k1 *= m; k1 ^= k1 >> r; k1 *= m;
       h1 *= m; h1 ^= k1;
       len -= 4;

       unsigned int k2 = *data++;
       k2 *= m; k2 ^= k2 >> r; k2 *= m;
       h2 *= m; h2 ^= k2;
       len -= 4;
    }

    if(len >= 4)
    {
       unsigned int k1 = *data++;
       k1 *= m; k1 ^= k1 >> r; k1 *= m;
       h1 *= m; h1 ^= k1;
       len -= 4;
    }

    switch(len)
    {
        case 3: h2 ^= ((unsigned char*)data)[2] << 16;
        case 2: h2 ^= ((unsigned char*)data)[1] << 8;
        case 1: h2 ^= ((unsigned char*)data)[0];
        h2 *= m;
    };

    h1 ^= h2 >> 18; h1 *= m;
    h2 ^= h1 >> 22; h2 *= m;
    h1 ^= h2 >> 17; h1 *= m;
    h2 ^= h1 >> 19; h2 *= m;

    uint64_t h = h1;

    h = (h << 32) | h2;

    return h;
}