1/*	$NetBSD: bitncmp.c,v 1.1.1.2 2012/09/09 16:08:00 christos Exp $	*/
2
3/*
4 * Copyright (C) 2004, 2005, 2008  Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (C) 1996, 1999, 2001  Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
12 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
13 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
14 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
15 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
16 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
17 * PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#if defined(LIBC_SCCS) && !defined(lint)
21static const char rcsid[] = "Id: bitncmp.c,v 1.5 2008/11/14 02:36:51 marka Exp ";
22#endif
23
24#include "port_before.h"
25
26#include <sys/types.h>
27
28#include <string.h>
29
30#include "port_after.h"
31
32#include <isc/misc.h>
33
34/*%
35 * int
36 * bitncmp(l, r, n)
37 *	compare bit masks l and r, for n bits.
38 * return:
39 *	-1, 1, or 0 in the libc tradition.
40 * note:
41 *	network byte order assumed.  this means 192.5.5.240/28 has
42 *	0x11110000 in its fourth octet.
43 * author:
44 *	Paul Vixie (ISC), June 1996
45 */
46int
47bitncmp(const void *l, const void *r, int n) {
48	u_int lb, rb;
49	int x, b;
50
51	b = n / 8;
52	x = memcmp(l, r, b);
53	if (x || (n % 8) == 0)
54		return (x);
55
56	lb = ((const u_char *)l)[b];
57	rb = ((const u_char *)r)[b];
58	for (b = n % 8; b > 0; b--) {
59		if ((lb & 0x80) != (rb & 0x80)) {
60			if (lb & 0x80)
61				return (1);
62			return (-1);
63		}
64		lb <<= 1;
65		rb <<= 1;
66	}
67	return (0);
68}
69
70/*! \file */
71