contrib/bind-9.2.4rc7/lib/bind/isc/bitncmp.c

   1 /*
   2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (c) 1996,1999 by Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and 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
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #if defined(LIBC_SCCS) && !defined(lint)
  19 static const char rcsid[] = "$Id: bitncmp.c,v 1.1.2.1 2004/03/09 09:17:34 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)
  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 }