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/*
* Copyright (c) 2009, Rambler media
* 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.
*
* THIS SOFTWARE IS PROVIDED BY Rambler media ''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 Rambler 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 "config.h"
#include "bloom.h"
/* 4 bits are used for counting (implementing delete operation) */
#define SIZE_BIT 4
/* These macroes are for 4 bits for counting element */
#define INCBIT(a, n, acc) do { \
acc = a[n * SIZE_BIT / CHAR_BIT] & (0xF << (n % (CHAR_BIT / SIZE_BIT) * SIZE_BIT)); \
acc ++; \
acc &= 0xF; \
\
a[n * SIZE_BIT / CHAR_BIT] &= (0xF << (4 - (n % (CHAR_BIT/SIZE_BIT) * SIZE_BIT))); \
a[n * SIZE_BIT / CHAR_BIT] |= (acc << (n % (CHAR_BIT/SIZE_BIT) * SIZE_BIT)); \
} while (0);
#define DECBIT(a, n, acc) do { \
acc = a[n * SIZE_BIT / CHAR_BIT] & (0xF << (n % (CHAR_BIT / SIZE_BIT) * SIZE_BIT)); \
acc --; \
acc &= 0xF; \
\
a[n * SIZE_BIT / CHAR_BIT] &= (0xF << (4 - (n % (CHAR_BIT/SIZE_BIT) * SIZE_BIT))); \
a[n * SIZE_BIT / CHAR_BIT] |= (acc << (n % (CHAR_BIT/SIZE_BIT) * SIZE_BIT)); \
} while (0);
#define GETBIT(a, n) (a[n * SIZE_BIT / CHAR_BIT] & (0xF << (n % (CHAR_BIT/SIZE_BIT) * SIZE_BIT)))
/* Common hash functions */
unsigned int
bloom_sax_hash (const char *key)
{
unsigned int h = 0;
while (*key)
h ^= (h << 5) + (h >> 2) + (unsigned char)*key++;
return h;
}
unsigned int
bloom_sdbm_hash (const char *key)
{
unsigned int h = 0;
while (*key)
h = (unsigned char)*key++ + (h << 6) + (h << 16) - h;
return h;
}
unsigned int
bloom_fnv_hash (const char *key)
{
unsigned int h = 0;
while (*key) {
h ^= (unsigned char)*key++;
h += (h << 1) + (h << 4) + (h << 7) + (h << 8) + (h << 24);
}
return h;
}
unsigned int
bloom_rs_hash (const char *key)
{
unsigned int b = 378551;
unsigned int a = 63689;
unsigned int hash = 0;
while (*key) {
hash = hash * a + (unsigned char)*key++;
a = a * b;
}
return hash;
}
unsigned int
bloom_js_hash (const char *key)
{
unsigned int hash = 1315423911;
while (*key) {
hash ^= ((hash << 5) + (unsigned char)*key++ + (hash >> 2));
}
return hash;
}
unsigned int
bloom_elf_hash (const char *key)
{
unsigned int hash = 0;
unsigned int x = 0;
while (*key) {
hash = (hash << 4) + (unsigned char)*key++;
if ((x = hash & 0xF0000000L) != 0) {
hash ^= (x >> 24);
}
hash &= ~x;
}
return hash;
}
unsigned int
bloom_bkdr_hash (const char *key)
{
unsigned int seed = 131; /* 31 131 1313 13131 131313 etc.. */
unsigned int hash = 0;
while (*key) {
hash = (hash * seed) + (unsigned char)*key++;
}
return hash;
}
unsigned int
bloom_ap_hash (const char *key)
{
unsigned int hash = 0xAAAAAAAA;
unsigned int i = 0;
while (*key) {
hash ^= ((i & 1) == 0) ? ((hash << 7) ^ ((unsigned char)*key) * (hash >> 3)) : (~((hash << 11) + (((unsigned char)*key) ^ (hash >> 5))));
key++;
}
return hash;
}
bloom_filter_t *
bloom_create (size_t size, size_t nfuncs, ...)
{
bloom_filter_t *bloom;
va_list l;
int n;
if (!(bloom = g_malloc (sizeof (bloom_filter_t)))) {
return NULL;
}
if (!(bloom->a = g_new0 (char, (size + CHAR_BIT - 1) / CHAR_BIT * SIZE_BIT))) {
g_free (bloom);
return NULL;
}
if (!(bloom->funcs = (hashfunc_t *) g_malloc (nfuncs * sizeof (hashfunc_t)))) {
g_free (bloom->a);
g_free (bloom);
return NULL;
}
va_start (l, nfuncs);
for (n = 0; n < nfuncs; ++n) {
bloom->funcs[n] = va_arg (l, hashfunc_t);
}
va_end (l);
bloom->nfuncs = nfuncs;
bloom->asize = size;
return bloom;
}
void
bloom_destroy (bloom_filter_t * bloom)
{
g_free (bloom->a);
g_free (bloom->funcs);
g_free (bloom);
}
gboolean
bloom_add (bloom_filter_t * bloom, const char *s)
{
size_t n;
u_char t;
for (n = 0; n < bloom->nfuncs; ++n) {
INCBIT (bloom->a, bloom->funcs[n] (s) % bloom->asize, t);
}
return TRUE;
}
gboolean
bloom_del (bloom_filter_t * bloom, const char *s)
{
size_t n;
u_char t;
for (n = 0; n < bloom->nfuncs; ++n) {
DECBIT (bloom->a, bloom->funcs[n] (s) % bloom->asize, t);
}
return TRUE;
}
gboolean
bloom_check (bloom_filter_t * bloom, const char *s)
{
size_t n;
for (n = 0; n < bloom->nfuncs; ++n) {
if (!(GETBIT (bloom->a, bloom->funcs[n] (s) % bloom->asize)))
return FALSE;
}
return TRUE;
}
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