sys/arch/atari/stand/ahdilabel/cksum.c

   1 /*      $NetBSD: cksum.c,v 1.2 2008/04/28 20:23:15 martin Exp $ */
   2
   3 /*
   4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Julian Coleman, Waldi Ravens and Leo Weppelman.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include "privahdi.h"
  33
  34 /*
  35  * Disklabel checksum.
  36  */
  37
  38 int
  39 dkcksum (struct disklabel *dl)
  40 {
  41         u_short *start, *end, sum = 0;
  42
  43         start = (u_short *)dl;
  44         end   = (u_short *)&dl->d_partitions[dl->d_npartitions];
  45         while (start < end)
  46                 sum ^= *start++;
  47         return (sum);
  48 }
  49
  50 /*
  51  * AHDI root sector checksum.
  52  */
  53
  54 u_int16_t
  55 ahdi_cksum (void *buf)
  56 {
  57         u_int16_t       *p = (u_int16_t *)buf;
  58         u_int16_t        csum = 0;
  59         int              i;
  60
  61         for (i = 0; i < 256; i++)
  62                 csum += *p++;
  63         return ((0x1234 - csum) & 0xffff);
  64 }