usr.bin/cksum/sum1.c

1.8   bjh21 /*	$NetBSD: sum1.c,v 1.8 2002/03/31 14:43:23 bjh21 Exp $	*/
1.4   glass
1.1     cgd /*-
1.3     cgd  * Copyright (c) 1991, 1993
1.3     cgd  *	The Regents of the University of California.  All rights reserved.
1.1     cgd  *
1.1     cgd  * Redistribution and use in source and binary forms, with or without
1.1     cgd  * modification, are permitted provided that the following conditions
1.1     cgd  * are met:
1.1     cgd  * 1. Redistributions of source code must retain the above copyright
1.1     cgd  *    notice, this list of conditions and the following disclaimer.
1.1     cgd  * 2. Redistributions in binary form must reproduce the above copyright
1.1     cgd  *    notice, this list of conditions and the following disclaimer in the
1.1     cgd  *    documentation and/or other materials provided with the distribution.
1.1     cgd  * 3. All advertising materials mentioning features or use of this software
1.1     cgd  *    must display the following acknowledgement:
1.1     cgd  *	This product includes software developed by the University of
1.1     cgd  *	California, Berkeley and its contributors.
1.1     cgd  * 4. Neither the name of the University nor the names of its contributors
1.1     cgd  *    may be used to endorse or promote products derived from this software
1.1     cgd  *    without specific prior written permission.
1.1     cgd  *
1.1     cgd  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
1.1     cgd  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.1     cgd  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.1     cgd  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
1.1     cgd  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
1.1     cgd  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
1.1     cgd  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
1.1     cgd  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
1.1     cgd  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
1.1     cgd  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
1.1     cgd  * SUCH DAMAGE.
1.1     cgd  */
1.1     cgd
1.6   lukem #include <sys/cdefs.h>
1.8   bjh21 #if defined(__RCSID) && !defined(lint)
1.4   glass #if 0
1.4   glass static char sccsid[] = "@(#)sum1.c	8.1 (Berkeley) 6/6/93";
1.4   glass #else
1.8   bjh21 __RCSID("$NetBSD: sum1.c,v 1.8 2002/03/31 14:43:23 bjh21 Exp $");
1.4   glass #endif
1.1     cgd #endif /* not lint */
1.1     cgd
1.1     cgd #include <sys/types.h>
1.1     cgd #include <unistd.h>
1.1     cgd
1.5     cgd #include "extern.h"
1.5     cgd
1.3     cgd int
1.1     cgd csum1(fd, cval, clen)
1.1     cgd 	register int fd;
1.5     cgd 	u_int32_t *cval, *clen;
1.1     cgd {
1.5     cgd 	register u_int32_t total;
1.1     cgd 	register int nr;
1.7  atatat 	register u_int thecrc;
1.1     cgd 	register u_char *p;
1.1     cgd 	u_char buf[8192];
1.1     cgd
1.1     cgd 	/*
1.1     cgd 	 * 16-bit checksum, rotating right before each addition;
1.1     cgd 	 * overflow is discarded.
1.1     cgd 	 */
1.7  atatat 	thecrc = total = 0;
1.1     cgd 	while ((nr = read(fd, buf, sizeof(buf))) > 0)
1.1     cgd 		for (total += nr, p = buf; nr--; ++p) {
1.7  atatat 			if (thecrc & 1)
1.7  atatat 				thecrc |= 0x10000;
1.7  atatat 			thecrc = ((thecrc >> 1) + *p) & 0xffff;
1.1     cgd 		}
1.1     cgd 	if (nr < 0)
1.1     cgd 		return(1);
1.1     cgd
1.7  atatat 	*cval = thecrc;
1.1     cgd 	*clen = total;
1.1     cgd 	return(0);
1.1     cgd }