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#include <sys/cdefs.h>
20__FBSDID("$FreeBSD$");
21
22#include "ohash_int.h"
23
24unsigned int
25ohash_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