1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
/* Boyer-Moore string search as found on the internet using Google */
#include <pthread.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include "bm.h"
#define MAX(a,b) ((a) < (b) ? (b) : (a))
static void
preBmBc(unsigned char *x,
int m,
int bmBc[])
{
int i;
for (i = 0; i < BM_ASIZE; ++i)
bmBc[i] = m;
for (i = 0; i < m - 1; ++i)
bmBc[x[i]] = m - i - 1;
}
static void
suffixes(unsigned char *x,
int m,
int *suff)
{
int f, g, i;
f = 0;
suff[m - 1] = m;
g = m - 1;
for (i = m - 2; i >= 0; --i)
{
if (i > g && suff[i + m - 1 - f] < i - g)
suff[i] = suff[i + m - 1 - f];
else
{
if (i < g)
g = i;
f = i;
while (g >= 0 && x[g] == x[g + m - 1 - f])
--g;
suff[i] = f - g;
}
}
}
static int
preBmGs(unsigned char *x, int m, int bmGs[])
{
int i, j, *suff;
suff = (int *) calloc(sizeof(int), m);
if (suff == NULL)
return -1;
suffixes(x, m, suff);
for (i = 0; i < m; ++i)
bmGs[i] = m;
j = 0;
for (i = m - 1; i >= -1; --i)
if (i == -1 || suff[i] == i + 1)
for (; j < m - 1 - i; ++j)
if (bmGs[j] == m)
bmGs[j] = m - 1 - i;
for (i = 0; i <= m - 2; ++i)
bmGs[m - 1 - suff[i]] = m - 1 - i;
free(suff);
return 0;
}
int
bm_init(BM *bmp,
unsigned char *x,
int m,
int icase)
{
int i;
memset(bmp, 0, sizeof(bmp));
bmp->icase = icase;
bmp->bmGs = (int *) calloc(sizeof(int), m);
if (bmp->bmGs == NULL)
return -1;
bmp->saved_m = m;
bmp->saved_x = (unsigned char *) malloc(m);
if (bmp->saved_x == NULL)
return -2;
for (i = 0; i < m; i++)
bmp->saved_x[i] = icase ? tolower(x[i]) : x[i];
/* Preprocessing */
if (preBmGs(bmp->saved_x, m, bmp->bmGs) < 0)
return -3;
preBmBc((unsigned char *) bmp->saved_x, m, bmp->bmBc);
return 0;
}
void
bm_destroy(BM *bmp)
{
if (bmp->bmGs)
free(bmp->bmGs);
if (bmp->saved_x)
free(bmp->saved_x);
}
/* Search for matches
**
** If mfun is defined, then call this function for each match.
** If mfun returns anything else but 0 abort the search. If the
** returned value is < 0 then return this value, else return the
** number of matches (so far).
**
** If mfun is NULL then stop at first match and return the position
*/
int
bm_search(BM *bmp,
unsigned char *y,
int n,
int (*mfun)(void *buf, int n, int pos))
{
int i, j, c;
int nm = 0;
/* Searching */
j = 0;
while (j <= n - bmp->saved_m)
{
for (i = bmp->saved_m - 1;
i >= 0 && bmp->saved_x[i] == (bmp->icase ? tolower(y[i + j]) : y[i + j]);
--i)
;
if (i < 0)
{
if (mfun)
{
++nm;
c = mfun(y, n, j);
if (c)
return (c < 0 ? c : nm);
j += bmp->bmGs[0];
}
else
return j;
}
else
{
unsigned char c = (bmp->icase ? tolower(y[i + j]) : y[i + j]);
j += MAX(bmp->bmGs[i], bmp->bmBc[c] - bmp->saved_m + 1 + i);
}
}
return mfun == NULL ? -1 : nm;
}
#if 0
int
main(int argc,
char *argv[])
{
int pos;
bm_setup(argv[1], strlen(argv[1]));
pos = bm_search(argv[2], strlen(argv[2]));
printf("Match at pos %d\n", pos);
exit(0);
}
#endif
|
