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/*
* libmowgli: A collection of useful routines for programming.
* hash.c: FNV-1 hashing implementation.
*
* Copyright (c) 2007 William Pitcock <nenolod -at- sacredspiral.co.uk>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice is present in all copies.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
#include "mowgli.h"
#define HASHINIT 0x811c9dc5
#define HASHBITS 16
#define HASHSIZE (1 << HASHBITS)/* 2^16 = 65536 */
int
mowgli_fnv_hash_string(const char *p)
{
static int htoast = 0;
unsigned int hval = HASHINIT;
if (htoast == 0)
{
mowgli_random_t *r = mowgli_random_create();
htoast = mowgli_random_int(r);
mowgli_object_unref(r);
}
if (!p)
return 0;
for (; *p != '\0'; ++p)
{
hval += (hval << 1) + (hval << 4) + (hval << 7) + (hval << 8) + (hval << 24);
hval ^= (tolower(*p) ^ htoast);
}
return (hval >> HASHBITS) ^ (hval & ((1 << HASHBITS) - 1)) % HASHSIZE;
}
int
mowgli_fnv_hash(unsigned int *p)
{
static int htoast = 0;
unsigned int hval = HASHINIT;
if (htoast == 0)
{
mowgli_random_t *r = mowgli_random_create();
htoast = mowgli_random_int(r);
mowgli_object_unref(r);
}
if (!p)
return 0;
for (; *p != '\0'; ++p)
{
hval += (hval << 1) + (hval << 4) + (hval << 7) + (hval << 8) + (hval << 24);
hval ^= (tolower(*p) ^ htoast);
}
return (hval >> HASHBITS) ^ (hval & ((1 << HASHBITS) - 1)) % HASHSIZE;
}
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