Home | History | Annotate | Line # | Download | only in lib 
      1 /* $OpenBSD: ohash_lookup_memory.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 (at) 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 
     20 #include "ohash_int.h"
     21 
     22 unsigned int
     23 ohash_lookup_memory(struct ohash *h, const char *k, size_t size, uint32_t hv)
     24 {
     25 	unsigned int	i, incr;
     26 	unsigned int	empty;
     27 
     28 #ifdef STATS_HASH
     29 	STAT_HASH_LOOKUP++;
     30 #endif
     31 	empty = NONE;
     32 	i = hv % h->size;
     33 	incr = ((hv % (h->size-2)) & ~1) + 1;
     34 	while (h->t[i].p != NULL) {
     35 #ifdef STATS_HASH
     36 		STAT_HASH_LENGTH++;
     37 #endif
     38 		if (h->t[i].p == DELETED) {
     39 			if (empty == NONE)
     40 				empty = i;
     41 		} else if (h->t[i].hv == hv &&
     42 		    memcmp(h->t[i].p+h->info.key_offset, k, size) == 0) {
     43 		    	if (empty != NONE) {
     44 				h->t[empty].hv = hv;
     45 				h->t[empty].p = h->t[i].p;
     46 				h->t[i].p = DELETED;
     47 				return empty;
     48 			} else {
     49 #ifdef STATS_HASH
     50 				STAT_HASH_POSITIVE++;
     51 #endif
     52 			}	return i;
     53 		}
     54 		i += incr;
     55 		if (i >= h->size)
     56 			i -= h->size;
     57 	}
     58 
     59 	/* Found an empty position.  */
     60 	if (empty != NONE)
     61 		i = empty;
     62 	h->t[i].hv = hv;
     63 	return i;
     64 }
     65