1 /*
2 * Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1996, 1999, 2001 Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #if defined(LIBC_SCCS) && !defined(lint)
19 static const char rcsid[] = "$Id: bitncmp.c,v 1.5 2008/11/14 02:36:51 marka Exp $";
20 #endif
21
22 #include "port_before.h"
23
24 #include <sys/types.h>
25
26 #include <string.h>
27
28 #include "port_after.h"
29
30 #include <isc/misc.h>
31
32 /*%
33 * int
34 * bitncmp(l, r, n)
35 * compare bit masks l and r, for n bits.
36 * return:
37 * -1, 1, or 0 in the libc tradition.
38 * note:
39 * network byte order assumed. this means 192.5.5.240/28 has
40 * 0x11110000 in its fourth octet.
41 * author:
42 * Paul Vixie (ISC), June 1996
43 */
44 int
bitncmp(const void * l,const void * r,int n)45 bitncmp(const void *l, const void *r, int n) {
46 u_int lb, rb;
47 int x, b;
48
49 b = n / 8;
50 x = memcmp(l, r, b);
51 if (x || (n % 8) == 0)
52 return (x);
53
54 lb = ((const u_char *)l)[b];
55 rb = ((const u_char *)r)[b];
56 for (b = n % 8; b > 0; b--) {
57 if ((lb & 0x80) != (rb & 0x80)) {
58 if (lb & 0x80)
59 return (1);
60 return (-1);
61 }
62 lb <<= 1;
63 rb <<= 1;
64 }
65 return (0);
66 }
67
68 /*! \file */
69