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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2013 Lennart Poettering
systemd 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.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include "util.h"
#include "MurmurHash3.h"
#include "bus-bloom.h"
static inline void set_bit(uint64_t filter[], unsigned b) {
filter[b >> 6] |= 1ULL << (b & 63);
}
void bloom_add_data(uint64_t filter[BLOOM_SIZE/8], const void *data, size_t n) {
uint16_t hash[8];
unsigned k = 0;
/*
* Our bloom filter has the following parameters:
*
* m=512 (bits in the filter)
* k=8 (hash functions)
*
* We calculate a single 128bit MurmurHash value of which we
* use 8 parts of 9 bits as individual hash functions.
*
*/
MurmurHash3_x64_128(data, n, 0, hash);
assert_cc(BLOOM_SIZE*8 == 512);
for (k = 0; k < ELEMENTSOF(hash); k++)
set_bit(filter, hash[k] & 511);
}
void bloom_add_pair(uint64_t filter[BLOOM_SIZE/8], const char *a, const char *b) {
size_t n;
char *c;
assert(filter);
assert(a);
assert(b);
n = strlen(a) + 1 + strlen(b);
c = alloca(n + 1);
strcpy(stpcpy(stpcpy(c, a), ":"), b);
bloom_add_data(filter, c, n);
}
void bloom_add_prefixes(uint64_t filter[BLOOM_SIZE/8], const char *a, const char *b, char sep) {
size_t n;
char *c, *p;
assert(filter);
assert(a);
assert(b);
n = strlen(a) + 1 + strlen(b);
c = alloca(n + 1);
p = stpcpy(stpcpy(c, a), ":");
strcpy(p, b);
for (;;) {
char *e;
e = strrchr(p, sep);
if (!e || e == p)
break;
*e = 0;
bloom_add_data(filter, c, e - c);
}
}
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