11590Srgrimes/*-
21590Srgrimes * Copyright (c) 1991, 1993
31590Srgrimes *	The Regents of the University of California.  All rights reserved.
41590Srgrimes *
51590Srgrimes * Redistribution and use in source and binary forms, with or without
61590Srgrimes * modification, are permitted provided that the following conditions
71590Srgrimes * are met:
81590Srgrimes * 1. Redistributions of source code must retain the above copyright
91590Srgrimes *    notice, this list of conditions and the following disclaimer.
101590Srgrimes * 2. Redistributions in binary form must reproduce the above copyright
111590Srgrimes *    notice, this list of conditions and the following disclaimer in the
121590Srgrimes *    documentation and/or other materials provided with the distribution.
131590Srgrimes * 4. Neither the name of the University nor the names of its contributors
141590Srgrimes *    may be used to endorse or promote products derived from this software
151590Srgrimes *    without specific prior written permission.
161590Srgrimes *
171590Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
181590Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
191590Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
201590Srgrimes * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
211590Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
221590Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
231590Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
241590Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
251590Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
261590Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
271590Srgrimes * SUCH DAMAGE.
281590Srgrimes */
291590Srgrimes
301590Srgrimes#ifndef lint
3154162Scharnier#if 0
3254162Scharnierstatic char sccsid[] = "@(#)sum1.c	8.1 (Berkeley) 6/6/93";
3354162Scharnier#endif
341590Srgrimes#endif /* not lint */
35112212Srobert
3699112Sobrien#include <sys/cdefs.h>
3799112Sobrien__FBSDID("$FreeBSD$");
381590Srgrimes
391590Srgrimes#include <sys/types.h>
40112212Srobert
411590Srgrimes#include <unistd.h>
42200462Sdelphij#include <stdint.h>
431590Srgrimes
4487212Smarkm#include "extern.h"
4587212Smarkm
461590Srgrimesint
47112212Srobertcsum1(int fd, uint32_t *cval, off_t *clen)
481590Srgrimes{
4987212Smarkm	int nr;
5087212Smarkm	u_int lcrc;
51112212Srobert	off_t total;
5287212Smarkm	u_char *p;
531590Srgrimes	u_char buf[8192];
541590Srgrimes
551590Srgrimes	/*
561590Srgrimes	 * 16-bit checksum, rotating right before each addition;
571590Srgrimes	 * overflow is discarded.
581590Srgrimes	 */
5987212Smarkm	lcrc = total = 0;
601590Srgrimes	while ((nr = read(fd, buf, sizeof(buf))) > 0)
611590Srgrimes		for (total += nr, p = buf; nr--; ++p) {
6287212Smarkm			if (lcrc & 1)
6387212Smarkm				lcrc |= 0x10000;
6487212Smarkm			lcrc = ((lcrc >> 1) + *p) & 0xffff;
651590Srgrimes		}
661590Srgrimes	if (nr < 0)
67112212Srobert		return (1);
681590Srgrimes
6987212Smarkm	*cval = lcrc;
701590Srgrimes	*clen = total;
71112212Srobert	return (0);
721590Srgrimes}
73