NetBSD/sys/arch/amiga/stand/bootblock/aout2bb/chksum.c

89 lines
2.8 KiB
C

/* $NetBSD: chksum.c,v 1.3 1999/02/16 23:34:10 is Exp $ */
/*-
* Copyright (c) 1996 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Ignatios Souvatzis.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include "chksum.h"
u_int32_t
chksum(block, size)
u_int32_t *block;
int size;
{
u_int32_t sum, lastsum;
int i;
sum = 0;
for (i=0; i<size; i++) {
lastsum = sum;
sum += block[i];
if (sum < lastsum)
++sum;
}
return sum;
}
#ifdef TESTSUM
u_int32_t myblock[8192];
int
main(int argc, char *argb[]) {
int bbsize;
u_int32_t cks, cks1;
bbsize=atol(argb[1]);
bbsize *= (512 / sizeof (u_int32_t));
if (4*bbsize != read(0, myblock, sizeof(u_int32_t)*bbsize)) {
fprintf(stderr, "short read\n");
exit(1);
}
fprintf(stderr, "Cksum field = 0x%x, ", myblock[1]);
cks = chksum(myblock, bbsize);
fprintf(stderr, "cksum = 0x%x\n", cks);
myblock[1] += 0xFFFFFFFF - cks;
fprintf(stderr, "New cksum field = 0x%x, ", myblock[1]);
cks1 = chksum(myblock, bbsize);
fprintf(stderr, "cksum = 0x%x\n", cks1);
}
#endif