usr.bin/m4/lib/ohash_lookup_memory.c

   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@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_memory.c,v 1.2 2012/11/17 01:54:24 svnexp Exp $
  20  */
  21
  22 #include "ohash_int.h"
  23
  24 unsigned int
  25 ohash_lookup_memory(struct ohash *h, const char *k, size_t size, uint32_t hv)
  26 {
  27         unsigned int    i, incr;
  28         unsigned int    empty;
  29
  30 #ifdef STATS_HASH
  31         STAT_HASH_LOOKUP++;
  32 #endif
  33         empty = NONE;
  34         i = hv % h->size;
  35         incr = ((hv % (h->size-2)) & ~1) + 1;
  36         while (h->t[i].p != NULL) {
  37 #ifdef STATS_HASH
  38                 STAT_HASH_LENGTH++;
  39 #endif
  40                 if (h->t[i].p == DELETED) {
  41                         if (empty == NONE)
  42                                 empty = i;
  43                 } else if (h->t[i].hv == hv &&
  44                     memcmp(h->t[i].p+h->info.key_offset, k, size) == 0) {
  45                         if (empty != NONE) {
  46                                 h->t[empty].hv = hv;
  47                                 h->t[empty].p = h->t[i].p;
  48                                 h->t[i].p = DELETED;
  49                                 return empty;
  50                         } else {
  51 #ifdef STATS_HASH
  52                                 STAT_HASH_POSITIVE++;
  53 #endif
  54                         }
  55                         return i;
  56                 }
  57                 i += incr;
  58                 if (i >= h->size)
  59                         i -= h->size;
  60         }
  61
  62         /* Found an empty position. */
  63         if (empty != NONE)
  64                 i = empty;
  65         h->t[i].hv = hv;
  66         return i;
  67 }