Hashes.cpp

#include "Hashes.h"

#include "Random.h"


#include <stdlib.h>
//#include <stdint.h>
#include <assert.h>
//#include <emmintrin.h>
//#include <xmmintrin.h>

//----------------------------------------------------------------------------
// fake / bad hashes

void BadHash ( const void * key, int len, uint32_t seed, void * out )
{
  uint32_t h = seed;

  const uint8_t * data = (const uint8_t*)key;

  for(int i = 0; i < len; i++)
  {
    h ^= h >> 3;
    h ^= h << 5;
    h ^= data[i];
  }

  *(uint32_t*)out = h;
}

void sumhash ( const void * key, int len, uint32_t seed, void * out )
{
  uint32_t h = seed;

  const uint8_t * data = (const uint8_t*)key;

  for(int i = 0; i < len; i++)
  {
    h += data[i];
  }

  *(uint32_t*)out = h;
}

void sumhash32 ( const void * key, int len, uint32_t seed, void * out )
{
  uint32_t h = seed;

  const uint32_t * data = (const uint32_t*)key;

  for(int i = 0; i < len/4; i++)
  {
    h += data[i];
  }

  *(uint32_t*)out = h;
}

void DoNothingHash ( const void *, int, uint32_t, void * )
{
}

//-----------------------------------------------------------------------------
// One-byte-at-a-time hash based on Murmur's mix

void MurmurOAAT ( const void * key, int len, uint32_t seed, void * out )
{
  const uint8_t * data = (const uint8_t*)key;

  uint32_t h = seed ^ len;

  for(int i = 0; i < len; i++)
  {
    h ^= data[i];
    h *= 0x5bd1e995;
    h ^= h >> 15;
  }

  h *= 0x5bd1e995;
  h ^= h >> 15;

  *(uint32_t*)out = h;
}

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

void FNV ( const void * key, int len, uint32_t seed, void * out )
{
  unsigned int h = seed;

  const uint8_t * data = (const uint8_t*)key;

  h ^= BIG_CONSTANT(2166136261);

  for(int i = 0; i < len; i++)
  {
    h ^= data[i];
    h *= 16777619;
  }

  *(uint32_t*)out = h;
}

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

uint32_t x17 ( const void * key, int len, uint32_t h ) 
{
  const uint8_t * data = (const uint8_t*)key;
    
  for(int i = 0; i < len; ++i) 
  {
        h = 17 * h + (data[i] - ' ');
    }

    return h ^ (h >> 16);
}

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

uint32_t Bernstein ( const void * key, int len, uint32_t h ) 
{
  const uint8_t * data = (const uint8_t*)key;
    
  for(int i = 0; i < len; ++i) 
  {
        h = 33 * h + data[i];
    }

  return h;
}

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