xref: /openbsd/lib/libc/uuid/uuid_hash.c (revision 264ca280)
1 /*	$OpenBSD: uuid_hash.c,v 1.2 2015/09/10 18:13:46 guenther Exp $	*/
2 /*	$NetBSD: uuid_hash.c,v 1.2 2008/04/23 07:52:32 plunky Exp $	*/
3 
4 /*
5  * Copyright (c) 2002 Marcel Moolenaar
6  * Copyright (c) 2002 Hiten Mahesh Pandya
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  * $FreeBSD: src/lib/libc/uuid/uuid_hash.c,v 1.2 2003/08/08 19:18:43 marcel Exp $
31  */
32 
33 #include <uuid.h>
34 
35 /*
36  * uuid_hash() - generate a hash value.
37  * See also:
38  *	http://www.opengroup.org/onlinepubs/009629399/uuid_hash.htm
39  */
40 uint16_t
41 uuid_hash(const uuid_t *u, uint32_t *status)
42 {
43 	if (status)
44 		*status = uuid_s_ok;
45 
46 	/*
47 	 * Use the most frequently changing bits in the UUID as the hash
48 	 * value. This should yield a good enough distribution...
49 	 */
50 	return ((u) ? u->time_low & 0xffff : 0);
51 }
52