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)
21 static 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 */
46 int
bitncmp(const void * l,const void * r,int n)47 bitncmp(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