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
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