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/* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* HashKit library
*
* Copyright (C) 2011-2012 Data Differential, http://datadifferential.com/
* Copyright (C) 2006-2009 Brian Aker All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * 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.
*
* * The names of its contributors may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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.
*
*/
/* By Paul Hsieh (C) 2004, 2005. Covered under the Paul Hsieh
* derivative license.
* See: http://www.azillionmonkeys.com/qed/weblicense.html for license
* details.
* http://www.azillionmonkeys.com/qed/hash.html
*/
#include <libhashkit/common.h>
#undef get16bits
#if (defined(__GNUC__) && defined(__i386__))
#define get16bits(d) (*((const uint16_t *) (d)))
#endif
#if !defined (get16bits)
#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
+(uint32_t)(((const uint8_t *)(d))[0]) )
#endif
#ifdef HAVE_HSIEH_HASH
uint32_t hashkit_hsieh(const char *key, size_t key_length, void *)
{
uint32_t hash = 0, tmp;
int rem;
if (key_length <= 0 || key == NULL)
return 0;
rem = key_length & 3;
key_length >>= 2;
/* Main loop */
for (;key_length > 0; key_length--)
{
hash += get16bits (key);
tmp = (get16bits (key+2) << 11) ^ hash;
hash = (hash << 16) ^ tmp;
key += 2*sizeof (uint16_t);
hash += hash >> 11;
}
/* Handle end cases */
switch (rem)
{
case 3: hash += get16bits (key);
hash ^= hash << 16;
hash ^= (uint32_t)key[sizeof (uint16_t)] << 18;
hash += hash >> 11;
break;
case 2: hash += get16bits (key);
hash ^= hash << 11;
hash += hash >> 17;
break;
case 1: hash += (unsigned char)(*key);
hash ^= hash << 10;
hash += hash >> 1;
default:
break;
}
/* Force "avalanching" of final 127 bits */
hash ^= hash << 3;
hash += hash >> 5;
hash ^= hash << 4;
hash += hash >> 17;
hash ^= hash << 25;
hash += hash >> 6;
return hash;
}
#else
uint32_t hashkit_hsieh(const char *, size_t , void *)
{
return 0;
}
#endif
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