external/bsd/libbind/dist/isc/bitncmp.c

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