/* $NetBSD: sum1.c,v 1.13 2005/02/05 00:13:34 simonb Exp $ */
/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
#include <sys/cdefs.h>
#if defined(__RCSID) && !defined(lint)
#if 0
static char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93";
#else
__RCSID("$NetBSD: sum1.c,v 1.13 2005/02/05 00:13:34 simonb Exp $");
#endif
#endif /* not lint */
#include <sys/types.h>
#include <unistd.h>
#include "extern.h"
int
csum1(int fd, u_int32_t *cval, off_t *clen)
{
off_t total;
int nr;
u_int thecrc;
u_char *p;
u_char buf[8192];
/*
* 16-bit checksum, rotating right before each addition;
* overflow is discarded.
*/
thecrc = total = 0;
while ((nr = read(fd, buf, sizeof(buf))) > 0)
for (total += nr, p = buf; nr--; ++p) {
if (thecrc & 1)
thecrc |= 0x10000;
thecrc = ((thecrc >> 1) + *p) & 0xffff;
}
if (nr < 0)
return 1;
*cval = thecrc;
*clen = total;
return 0;
}
