1/*	$NetBSD: sum1.c,v 1.14 2021/03/18 18:12:35 cheusov Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#if HAVE_NBTOOL_CONFIG_H
33#include "nbtool_config.h"
34#endif
35
36#include <sys/cdefs.h>
37#if defined(__RCSID) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)sum1.c	8.1 (Berkeley) 6/6/93";
40#else
41__RCSID("$NetBSD: sum1.c,v 1.14 2021/03/18 18:12:35 cheusov Exp $");
42#endif
43#endif /* not lint */
44
45#include <sys/types.h>
46#include <unistd.h>
47
48#include "extern.h"
49
50int
51csum1(int fd, uint32_t *cval, off_t *clen)
52{
53	off_t total;
54	int nr;
55	u_int thecrc;
56	u_char *p;
57	u_char buf[8192];
58
59	/*
60	 * 16-bit checksum, rotating right before each addition;
61	 * overflow is discarded.
62	 */
63	thecrc = total = 0;
64	while ((nr = read(fd, buf, sizeof(buf))) > 0)
65		for (total += nr, p = buf; nr--; ++p) {
66			if (thecrc & 1)
67				thecrc |= 0x10000;
68			thecrc = ((thecrc >> 1) + *p) & 0xffff;
69		}
70	if (nr < 0)
71		return 1;
72
73	*cval = thecrc;
74	*clen = total;
75	return 0;
76}
77