lib/libc/uuid/uuid_hash.c

   1 /*      $NetBSD: uuid_hash.c,v 1.2 2008/04/23 07:52:32 plunky Exp $     */
   2
   3 /*-
   4  * Copyright (c) 2002 Marcel Moolenaar
   5  * Copyright (c) 2002 Hiten Mahesh Pandya
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD: src/lib/libc/uuid/uuid_hash.c,v 1.2 2003/08/08 19:18:43 marcel Exp $
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 __RCSID("$NetBSD: uuid_hash.c,v 1.2 2008/04/23 07:52:32 plunky Exp $");
  35 #endif
  36
  37 #include "namespace.h"
  38
  39 #include <uuid.h>
  40
  41 /*
  42  * uuid_hash() - generate a hash value.
  43  * See also:
  44  *      http://www.opengroup.org/onlinepubs/009629399/uuid_hash.htm
  45  */
  46 uint16_t
  47 uuid_hash(const uuid_t *u, uint32_t *status)
  48 {
  49
  50         if (status)
  51                 *status = uuid_s_ok;
  52
  53         /*
  54          * Use the most frequently changing bits in the UUID as the hash
  55          * value. This should yield a good enough distribution...
  56          */
  57         return ((u) ? u->time_low & 0xffff : 0);
  58 }