1 /* $OpenBSD: ohash_lookup_interval.c,v 1.3 2006/01/16 15:52:25 espie Exp $ */
2 /* ex:ts=8 sw=4:
3 */
4
5 /* Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 *
19 * $FreeBSD: src/usr.bin/m4/lib/ohash_lookup_interval.c,v 1.2 2012/11/17 01:54:24 svnexp Exp $
20 */
21
22 #include "ohash_int.h"
23
24 unsigned int
ohash_lookup_interval(struct ohash * h,const char * start,const char * end,uint32_t hv)25 ohash_lookup_interval(struct ohash *h, const char *start, const char *end,
26 uint32_t hv)
27 {
28 unsigned int i, incr;
29 unsigned int empty;
30
31 #ifdef STATS_HASH
32 STAT_HASH_LOOKUP++;
33 #endif
34 empty = NONE;
35 i = hv % h->size;
36 incr = ((hv % (h->size-2)) & ~1) + 1;
37 while (h->t[i].p != NULL) {
38 #ifdef STATS_HASH
39 STAT_HASH_LENGTH++;
40 #endif
41 if (h->t[i].p == DELETED) {
42 if (empty == NONE)
43 empty = i;
44 } else if (h->t[i].hv == hv &&
45 strncmp(h->t[i].p+h->info.key_offset, start,
46 end - start) == 0 &&
47 (h->t[i].p+h->info.key_offset)[end-start] == '\0') {
48 if (empty != NONE) {
49 h->t[empty].hv = hv;
50 h->t[empty].p = h->t[i].p;
51 h->t[i].p = DELETED;
52 return empty;
53 } else {
54 #ifdef STATS_HASH
55 STAT_HASH_POSITIVE++;
56 #endif
57 return i;
58 }
59 }
60 i += incr;
61 if (i >= h->size)
62 i -= h->size;
63 }
64
65 /* Found an empty position. */
66 if (empty != NONE)
67 i = empty;
68 h->t[i].hv = hv;
69 return i;
70 }
71