ts_kmp.c (05668381140309088443bf5dc53add4104610fbb) ts_kmp.c (2523c3fc2bc9e34c06a71517844d55353f1f904a)
1/*
2 * lib/ts_kmp.c Knuth-Morris-Pratt text search implementation
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *

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28 * [1] Cormen, Leiserson, Rivest, Stein
29 * Introdcution to Algorithms, 2nd Edition, MIT Press
30 * [2] See finite automation theory
31 */
32
33#include <linux/module.h>
34#include <linux/types.h>
35#include <linux/string.h>
1/*
2 * lib/ts_kmp.c Knuth-Morris-Pratt text search implementation
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *

--- 19 unchanged lines hidden (view full) ---

28 * [1] Cormen, Leiserson, Rivest, Stein
29 * Introdcution to Algorithms, 2nd Edition, MIT Press
30 * [2] See finite automation theory
31 */
32
33#include <linux/module.h>
34#include <linux/types.h>
35#include <linux/string.h>
36#include <linux/ctype.h>
36#include <linux/textsearch.h>
37
38struct ts_kmp
39{
40 u8 * pattern;
41 unsigned int pattern_len;
42 unsigned int prefix_tbl[0];
43};
44
45static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state)
46{
47 struct ts_kmp *kmp = ts_config_priv(conf);
48 unsigned int i, q = 0, text_len, consumed = state->offset;
49 const u8 *text;
37#include <linux/textsearch.h>
38
39struct ts_kmp
40{
41 u8 * pattern;
42 unsigned int pattern_len;
43 unsigned int prefix_tbl[0];
44};
45
46static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state)
47{
48 struct ts_kmp *kmp = ts_config_priv(conf);
49 unsigned int i, q = 0, text_len, consumed = state->offset;
50 const u8 *text;
51 const int icase = conf->flags & TS_IGNORECASE;
50
51 for (;;) {
52 text_len = conf->get_next_block(consumed, &text, conf, state);
53
54 if (unlikely(text_len == 0))
55 break;
56
57 for (i = 0; i < text_len; i++) {
52
53 for (;;) {
54 text_len = conf->get_next_block(consumed, &text, conf, state);
55
56 if (unlikely(text_len == 0))
57 break;
58
59 for (i = 0; i < text_len; i++) {
58 while (q > 0 && kmp->pattern[q] != text[i])
60 while (q > 0 && kmp->pattern[q]
61 != (icase ? toupper(text[i]) : text[i]))
59 q = kmp->prefix_tbl[q - 1];
62 q = kmp->prefix_tbl[q - 1];
60 if (kmp->pattern[q] == text[i])
63 if (kmp->pattern[q]
64 == (icase ? toupper(text[i]) : text[i]))
61 q++;
62 if (unlikely(q == kmp->pattern_len)) {
63 state->offset = consumed + i + 1;
64 return state->offset - kmp->pattern_len;
65 }
66 }
67
68 consumed += text_len;
69 }
70
71 return UINT_MAX;
72}
73
74static inline void compute_prefix_tbl(const u8 *pattern, unsigned int len,
65 q++;
66 if (unlikely(q == kmp->pattern_len)) {
67 state->offset = consumed + i + 1;
68 return state->offset - kmp->pattern_len;
69 }
70 }
71
72 consumed += text_len;
73 }
74
75 return UINT_MAX;
76}
77
78static inline void compute_prefix_tbl(const u8 *pattern, unsigned int len,
75 unsigned int *prefix_tbl)
79 unsigned int *prefix_tbl, int flags)
76{
77 unsigned int k, q;
80{
81 unsigned int k, q;
82 const u8 icase = flags & TS_IGNORECASE;
78
79 for (k = 0, q = 1; q < len; q++) {
83
84 for (k = 0, q = 1; q < len; q++) {
80 while (k > 0 && pattern[k] != pattern[q])
85 while (k > 0 && (icase ? toupper(pattern[k]) : pattern[k])
86 != (icase ? toupper(pattern[q]) : pattern[q]))
81 k = prefix_tbl[k-1];
87 k = prefix_tbl[k-1];
82 if (pattern[k] == pattern[q])
88 if ((icase ? toupper(pattern[k]) : pattern[k])
89 == (icase ? toupper(pattern[q]) : pattern[q]))
83 k++;
84 prefix_tbl[q] = k;
85 }
86}
87
88static struct ts_config *kmp_init(const void *pattern, unsigned int len,
90 k++;
91 prefix_tbl[q] = k;
92 }
93}
94
95static struct ts_config *kmp_init(const void *pattern, unsigned int len,
89 gfp_t gfp_mask)
96 gfp_t gfp_mask, int flags)
90{
91 struct ts_config *conf;
92 struct ts_kmp *kmp;
97{
98 struct ts_config *conf;
99 struct ts_kmp *kmp;
100 int i;
93 unsigned int prefix_tbl_len = len * sizeof(unsigned int);
94 size_t priv_size = sizeof(*kmp) + len + prefix_tbl_len;
95
96 conf = alloc_ts_config(priv_size, gfp_mask);
97 if (IS_ERR(conf))
98 return conf;
99
101 unsigned int prefix_tbl_len = len * sizeof(unsigned int);
102 size_t priv_size = sizeof(*kmp) + len + prefix_tbl_len;
103
104 conf = alloc_ts_config(priv_size, gfp_mask);
105 if (IS_ERR(conf))
106 return conf;
107
108 conf->flags = flags;
100 kmp = ts_config_priv(conf);
101 kmp->pattern_len = len;
109 kmp = ts_config_priv(conf);
110 kmp->pattern_len = len;
102 compute_prefix_tbl(pattern, len, kmp->prefix_tbl);
111 compute_prefix_tbl(pattern, len, kmp->prefix_tbl, flags);
103 kmp->pattern = (u8 *) kmp->prefix_tbl + prefix_tbl_len;
112 kmp->pattern = (u8 *) kmp->prefix_tbl + prefix_tbl_len;
104 memcpy(kmp->pattern, pattern, len);
113 if (flags & TS_IGNORECASE)
114 for (i = 0; i < len; i++)
115 kmp->pattern[i] = toupper(((u8 *)pattern)[i]);
116 else
117 memcpy(kmp->pattern, pattern, len);
105
106 return conf;
107}
108
109static void *kmp_get_pattern(struct ts_config *conf)
110{
111 struct ts_kmp *kmp = ts_config_priv(conf);
112 return kmp->pattern;

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119 return conf;
120}
121
122static void *kmp_get_pattern(struct ts_config *conf)
123{
124 struct ts_kmp *kmp = ts_config_priv(conf);
125 return kmp->pattern;

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