path: root/src/ck_ht_hash.h

/*
 * Copyright 2012-2015 Samy Al Bahra
 * Copyright 2011-2014 AppNexus, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef CK_HT_HASH_H
#define CK_HT_HASH_H

/*
 * This is the Murmur hash written by Austin Appleby.
 */

#include <ck_stdint.h>
#include <ck_string.h>

//-----------------------------------------------------------------------------
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.

// Note - The x86 and x64 versions do _not_ produce the same results, as the
// algorithms are optimized for their respective platforms. You can still
// compile and run any of them on any platform, but your performance with the
// non-native version will be less than optimal.

//-----------------------------------------------------------------------------
// Platform-specific functions and macros

// Microsoft Visual Studio

#if defined(_MSC_VER)

#define FORCE_INLINE    __forceinline

#include <stdlib.h>

#define ROTL32(x,y)     _rotl(x,y)
#define ROTL64(x,y)     _rotl64(x,y)

#define BIG_CONSTANT(x) (x)

// Other compilers

#else   // defined(_MSC_VER)

#define FORCE_INLINE inline __attribute__((always_inline))

static inline uint32_t rotl32 ( uint32_t x, int8_t r )
{
  return (x << r) | (x >> (32 - r));
}

static inline uint64_t rotl64 ( uint64_t x, int8_t r )
{
  return (x << r) | (x >> (64 - r));
}

#define ROTL32(x,y)     rotl32(x,y)
#define ROTL64(x,y)     rotl64(x,y)

#define BIG_CONSTANT(x) (x##LLU)

#endif // !defined(_MSC_VER)

//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here

FORCE_INLINE static uint32_t getblock ( const uint32_t * p, int i )
{
  return p[i];
}

//-----------------------------------------------------------------------------
// Finalization mix - force all bits of a hash block to avalanche

FORCE_INLINE static uint32_t fmix ( uint32_t h )
{
  h ^= h >> 16;
  h *= 0x85ebca6b;
  h ^= h >> 13;
  h *= 0xc2b2ae35;
  h ^= h >> 16;

  return h;
}

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

static inline void MurmurHash3_x86_32 ( const void * key, int len,
                          uint32_t seed, uint32_t * out )
{
  const uint8_t * data = (const uint8_t*)key;
  const int nblocks = len / 4;
  int i;

  uint32_t h1 = seed;

  uint32_t c1 = 0xcc9e2d51;
  uint32_t c2 = 0x1b873593;

  //----------
  // body

  const uint32_t * blocks = (const uint32_t *)(const void *)(data + nblocks*4);

  for(i = -nblocks; i; i++)
  {
    uint32_t k1 = getblock(blocks,i);

    k1 *= c1;
    k1 = ROTL32(k1,15);
    k1 *= c2;

    h1 ^= k1;
    h1 = ROTL32(h1,13);
    h1 = h1*5+0xe6546b64;
  }

  //----------
  // tail

  const uint8_t * tail = (const uint8_t*)(data + nblocks*4);

  uint32_t k1 = 0;

  switch(len & 3)
  {
  case 3: k1 ^= tail[2] << 16;
  case 2: k1 ^= tail[1] << 8;
  case 1: k1 ^= tail[0];
          k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1;
  };

  //----------
  // finalization

  h1 ^= len;

  h1 = fmix(h1);

  *(uint32_t *)out = h1;
}

static inline uint64_t MurmurHash64A ( const void * key, int len, uint64_t seed )
{
  const uint64_t m = BIG_CONSTANT(0xc6a4a7935bd1e995);
  const int r = 47;

  uint64_t h = seed ^ (len * m);

  const uint64_t * data = (const uint64_t *)key;
  const uint64_t * end = data + (len/8);

  while(data != end)
  {
    uint64_t k;

    if (!((uintptr_t)data & 0x7))
	    k = *data++;
    else {
	    memcpy(&k, data, sizeof(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;
}


// 64-bit hash for 32-bit platforms

static inline uint64_t MurmurHash64B ( const void * key, int len, uint64_t seed )
{
  const uint32_t m = 0x5bd1e995;
  const int r = 24;

  uint32_t h1 = (uint32_t)(seed) ^ len;
  uint32_t h2 = (uint32_t)(seed >> 32);

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

  while(len >= 8)
  {
    uint32_t k1 = *data++;
    k1 *= m; k1 ^= k1 >> r; k1 *= m;
    h1 *= m; h1 ^= k1;
    len -= 4;

    uint32_t k2 = *data++;
    k2 *= m; k2 ^= k2 >> r; k2 *= m;
    h2 *= m; h2 ^= k2;
    len -= 4;
  }

  if(len >= 4)
  {
    uint32_t k1 = *data++;
    k1 *= m; k1 ^= k1 >> r; k1 *= m;
    h1 *= m; h1 ^= k1;
    len -= 4;
  }

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

#endif /* CK_HT_HASH_H */