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