usr.bin/m4/lib/ohash_interval.c

   1 /* $OpenBSD: ohash_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
  20 #include "ohash_int.h"
  21
  22 uint32_t
  23 ohash_interval(const char *s, const char **e)
  24 {
  25         uint32_t k;
  26
  27         if (!*e)
  28                 *e = s + strlen(s);
  29         if (s == *e)
  30                 k = 0;
  31         else
  32                 k = *s++;
  33         while (s != *e)
  34                 k =  ((k << 2) | (k >> 30)) ^ *s++;
  35         return k;
  36 }