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
  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 }