/* $Id: bitncmp.c,v 1.8 2009-11-02 11:55:54 yangtse Exp $ */ /* * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1996,1999 by Internet Software Consortium. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #ifndef HAVE_BITNCMP #include "ares_setup.h" #include "bitncmp.h" /* * int * bitncmp(l, r, n) * compare bit masks l and r, for n bits. * return: * -1, 1, or 0 in the libc tradition. * note: * network byte order assumed. this means 192.5.5.240/28 has * 0x11110000 in its fourth octet. * author: * Paul Vixie (ISC), June 1996 */ int ares_bitncmp(const void *l, const void *r, int n) { unsigned int lb, rb; int x, b; b = n / 8; x = memcmp(l, r, b); if (x || (n % 8) == 0) return (x); lb = ((const unsigned char *)l)[b]; rb = ((const unsigned char *)r)[b]; for (b = n % 8; b > 0; b--) { if ((lb & 0x80) != (rb & 0x80)) { if (lb & 0x80) return (1); return (-1); } lb <<= 1; rb <<= 1; } return (0); } #endif