xref: /src/sys/arch/atari/stand/ahdilabel/cksum.c

/*	$NetBSD: cksum.c,v 1.1.1.1.134.1 2008/05/16 02:22:05 yamt Exp $	*/

/*
 * Copyright (c) 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Julian Coleman, Waldi Ravens and Leo Weppelman.
 *
 * 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.
 *
 * 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 "privahdi.h"

/*
 * Disklabel checksum.
 */

int
dkcksum (dl)
	struct disklabel	*dl;
{
	u_short	*start, *end, sum = 0;

	start = (u_short *)dl;
	end   = (u_short *)&dl->d_partitions[dl->d_npartitions];
	while (start < end)
		sum ^= *start++;
	return (sum);
}

/*
 * AHDI root sector checksum.
 */

u_int16_t
ahdi_cksum (buf)
	void	*buf;
{
	u_int16_t	*p = (u_int16_t *)buf;
	u_int16_t	 csum = 0;
	int		 i;

	for (i = 0; i < 256; i++)
		csum += *p++;
	return ((0x1234 - csum) & 0xffff);
}