/* EINA - EFL data type library
 * Copyright (C) 2002-2008 Carsten Haitzler
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library;
 * if not, see <http://www.gnu.org/licenses/>.
 */

#ifndef EINA_INLINE_HASH_X_
#define EINA_INLINE_HASH_X_

/*
  djb2 hash algorithm was first reported by dan bernstein, and was the old
  default hash function for evas.
 */
static inline int
eina_hash_djb2(const char *key, int len)
{
   unsigned int hash_num = 5381;
   const unsigned char *ptr;

   if (!key) return 0;
   for (ptr = (unsigned char *)key; len; ptr++, len--)
     hash_num = ((hash_num << 5) + hash_num) ^ *ptr; /* hash * 33 ^ c */

   return (int)hash_num;
}

static inline int
eina_hash_djb2_len(const char *key, int *plen)
{
   unsigned int hash_num = 5381;
   int len = 0;
   const unsigned char *ptr;

   if (!key) return 0;

   for (ptr = (unsigned char *)key; *ptr; ptr++, len++)
     hash_num = ((hash_num << 5) + hash_num) ^ *ptr; /* hash * 33 ^ c */

   *plen = len + 1;

   return (int)hash_num;
}

static inline int
eina_hash_int32(const unsigned int *pkey, int len)
{
   unsigned int key = *pkey;

   (void) len;

   key  = ~key + (key << 15);
   key ^= key >> 12;
   key += key << 2;
   key ^= key >> 4;
   key *= 2057;
   key ^= key >> 16;
   return key;
}

static inline int
eina_hash_int64(const unsigned long int *pkey, int len)
{
   unsigned long int key = *pkey;

   (void) len;

   key  = ~key + (key << 18);
   key ^= key >> 31;
   key *= 21;
   key ^= key >> 11;
   key += key << 6;
   key ^= key >> 22;
   return (int) key;
}

static inline unsigned int _rotl32(unsigned int x, char r)
{
   return (x << r) | (x >> (32 - r));
}

static inline unsigned int _fmix32(unsigned int h)
{
   h ^= h >> 16;
   h *= 0x85ebca6b;
   h ^= h >> 13;
   h *= 0xc2b2ae35;
   h ^= h >> 16;

   return h;
}

static inline int
eina_hash_murmur3(const char *key, int len)
{
   const unsigned char * data = (const unsigned char*)key;
   const int nblocks = len / 4;
   unsigned int h1 = 0, k1;
   unsigned int c1 = 0xcc9e2d51;
   unsigned int c2 = 0x1b873593;
   const unsigned int * blocks = (const unsigned int *)(data + nblocks*4);
   int i;
   const unsigned char *tail;

   for(i = -nblocks; i; i++)
     {
        k1 = blocks[i];

        k1 *= c1;
        k1 = _rotl32(k1, 15);
        k1 *= c2;

        h1 ^= k1;
        h1 = _rotl32(h1, 13);
        h1 = h1*5+0xe6546b64;
     }

   tail = (const unsigned char*)(data + nblocks*4);

   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, 16);
         k1 *= c2;
         h1 ^= k1;
     }

   h1 ^= len;

   return _fmix32(h1);
}
#endif
