1 /* $Id: man_hash.c,v 1.29 2014/12/01 08:05:52 schwarze Exp $ */
2 /*
3 * Copyright (c) 2008, 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17 #include "config.h"
18
19 #include <sys/types.h>
20
21 #include <assert.h>
22 #include <ctype.h>
23 #include <limits.h>
24 #include <string.h>
25
26 #include "man.h"
27 #include "libman.h"
28
29 #define HASH_DEPTH 6
30
31 #define HASH_ROW(x) do { \
32 if (isupper((unsigned char)(x))) \
33 (x) -= 65; \
34 else \
35 (x) -= 97; \
36 (x) *= HASH_DEPTH; \
37 } while (/* CONSTCOND */ 0)
38
39 /*
40 * Lookup table is indexed first by lower-case first letter (plus one
41 * for the period, which is stored in the last row), then by lower or
42 * uppercase second letter. Buckets correspond to the index of the
43 * macro (the integer value of the enum stored as a char to save a bit
44 * of space).
45 */
46 static unsigned char table[26 * HASH_DEPTH];
47
48
49 /*
50 * XXX - this hash has global scope, so if intended for use as a library
51 * with multiple callers, it will need re-invocation protection.
52 */
53 void
man_hash_init(void)54 man_hash_init(void)
55 {
56 int i, j, x;
57
58 memset(table, UCHAR_MAX, sizeof(table));
59
60 assert(MAN_MAX < UCHAR_MAX);
61
62 for (i = 0; i < (int)MAN_MAX; i++) {
63 x = man_macronames[i][0];
64
65 assert(isalpha((unsigned char)x));
66
67 HASH_ROW(x);
68
69 for (j = 0; j < HASH_DEPTH; j++)
70 if (UCHAR_MAX == table[x + j]) {
71 table[x + j] = (unsigned char)i;
72 break;
73 }
74
75 assert(j < HASH_DEPTH);
76 }
77 }
78
79 enum mant
man_hash_find(const char * tmp)80 man_hash_find(const char *tmp)
81 {
82 int x, y, i;
83 enum mant tok;
84
85 if ('\0' == (x = tmp[0]))
86 return(MAN_MAX);
87 if ( ! (isalpha((unsigned char)x)))
88 return(MAN_MAX);
89
90 HASH_ROW(x);
91
92 for (i = 0; i < HASH_DEPTH; i++) {
93 if (UCHAR_MAX == (y = table[x + i]))
94 return(MAN_MAX);
95
96 tok = (enum mant)y;
97 if (0 == strcmp(tmp, man_macronames[tok]))
98 return(tok);
99 }
100
101 return(MAN_MAX);
102 }
103