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652ae149 JA |
1 | #include <stdlib.h> |
2 | #include <inttypes.h> | |
3 | ||
4 | #include "bloom.h" | |
5 | #include "../hash.h" | |
6 | ||
7 | struct bloom { | |
8 | uint64_t nentries; | |
9 | ||
10 | uint32_t *map; | |
11 | }; | |
12 | ||
13 | #define BITS_PER_INDEX (sizeof(uint32_t) * 8) | |
14 | #define BITS_INDEX_MASK (BITS_PER_INDEX - 1) | |
15 | ||
16 | static unsigned int jhash_init[] = { 0, 0x12db635, 0x2a4a53 }; | |
17 | #define N_HASHES 3 | |
18 | ||
19 | struct bloom *bloom_new(uint64_t entries) | |
20 | { | |
21 | struct bloom *b; | |
22 | size_t no_uints; | |
23 | ||
24 | b = malloc(sizeof(*b)); | |
25 | b->nentries = entries; | |
26 | no_uints = (entries + BITS_PER_INDEX - 1) / BITS_PER_INDEX; | |
27 | b->map = calloc(no_uints, sizeof(uint32_t)); | |
28 | if (!b->map) { | |
29 | free(b); | |
30 | return NULL; | |
31 | } | |
32 | ||
33 | return b; | |
34 | } | |
35 | ||
36 | void bloom_free(struct bloom *b) | |
37 | { | |
38 | free(b->map); | |
39 | free(b); | |
40 | } | |
41 | ||
42 | static int __bloom_check(struct bloom *b, uint32_t *data, unsigned int nwords, | |
43 | int set) | |
44 | { | |
45 | uint32_t hashes[N_HASHES]; | |
46 | int i, was_set; | |
47 | ||
48 | for (i = 0; i < N_HASHES; i++) | |
49 | hashes[i] = jhash(data, nwords, jhash_init[i]) % b->nentries; | |
50 | ||
51 | was_set = 0; | |
52 | for (i = 0; i < N_HASHES; i++) { | |
53 | const unsigned int index = hashes[i] / BITS_PER_INDEX; | |
54 | const unsigned int bit = hashes[i] & BITS_INDEX_MASK; | |
55 | ||
56 | if (b->map[index] & (1U << bit)) | |
57 | was_set++; | |
58 | if (set) | |
59 | b->map[index] |= 1U << bit; | |
60 | } | |
61 | ||
62 | return was_set == N_HASHES; | |
63 | } | |
64 | ||
65 | int bloom_check(struct bloom *b, uint32_t *data, unsigned int nwords) | |
66 | { | |
67 | return __bloom_check(b, data, nwords, 0); | |
68 | } | |
69 | ||
70 | int bloom_set(struct bloom *b, uint32_t *data, unsigned int nwords) | |
71 | { | |
72 | return __bloom_check(b, data, nwords, 1); | |
73 | } |