1 /* 2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the project nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD: src/usr.sbin/route6d/misc/cksum.c,v 1.1 1999/12/28 02:37:10 shin Exp $ 30 * $DragonFly: src/usr.sbin/route6d/misc/cksum.c,v 1.2 2003/06/17 04:30:02 dillon Exp $ 31 */ 32 33 #include <stdio.h> 34 35 unsigned short buf[BUFSIZ]; 36 37 main() 38 { 39 int i; 40 unsigned short *p = buf, *q = &buf[4]; 41 unsigned long sum, sum2; 42 43 while (scanf("%x", &i) != EOF) { 44 *p++ = i; printf("%d ", i); 45 } 46 printf("\n"); 47 48 sum = buf[2] + (buf[3] >> 8) & 0xff; 49 while (q != p) 50 sum += (*q++ & 0xffff); 51 sum2 = (sum & 0xffff) + (sum >> 16) & 0xffff; 52 printf("%x, %x\n", sum, sum2); 53 } 54