usr/src/lib/libresolv2/common/isc/bitncmp.c

   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 #include "port_before.h"
  19
  20 #include <sys/types.h>
  21
  22 #include <string.h>
  23
  24 #include "port_after.h"
  25
  26 #include <isc/misc.h>
  27
  28 /*%
  29  * int
  30  * bitncmp(l, r, n)
  31  *      compare bit masks l and r, for n bits.
  32  * return:
  33  *      -1, 1, or 0 in the libc tradition.
  34  * note:
  35  *      network byte order assumed.  this means 192.5.5.240/28 has
  36  *      0x11110000 in its fourth octet.
  37  * author:
  38  *      Paul Vixie (ISC), June 1996
  39  */
  40 int
  41 bitncmp(const void *l, const void *r, int n) {
  42         u_int lb, rb;
  43         int x, b;
  44
  45         b = n / 8;
  46         x = memcmp(l, r, b);
  47         if (x || (n % 8) == 0)
  48                 return (x);
  49
  50         lb = ((const u_char *)l)[b];
  51         rb = ((const u_char *)r)[b];
  52         for (b = n % 8; b > 0; b--) {
  53                 if ((lb & 0x80) != (rb & 0x80)) {
  54                         if (lb & 0x80)
  55                                 return (1);
  56                         return (-1);
  57                 }
  58                 lb <<= 1;
  59                 rb <<= 1;
  60         }
  61         return (0);
  62 }
  63
  64 /*! \file */