cksum.c

wm PNE 3.3 source code, running at more than vxworks6.x version.

/* $Header: /usr/cvsroot/target/src/wrn/wm/demo/lib/cksum.c,v 1.3 2003/01/15 14:04:31 josh Exp $ */

/*
 * Copyright (C) 1999-2005 Wind River Systems, Inc.
 * All rights reserved.  Provided under license only.
 * Distribution or other use of this software is only
 * permitted pursuant to the terms of a license agreement
 * from Wind River Systems (and is otherwise prohibited).
 * Refer to that license agreement for terms of use.
 */



/****************************************************************************
 *  Copyright 1993-1997 Epilogue Technology Corporation.
 *  Copyright 1998 Integrated Systems, Inc.
 *  All rights reserved.
 ****************************************************************************/

/*
 * $Log: cksum.c,v $
 * Revision 1.3  2003/01/15 14:04:31  josh
 * directory structure shifting
 *
 * Revision 1.2  2001/11/08 15:56:20  tneale
 * Updated for newest file layout
 *
 * Revision 1.1.1.1  2001/11/05 17:48:41  tneale
 * Tornado shuffle
 *
 * Revision 1.3  2001/01/19 22:23:40  paul
 * Update copyright.
 *
 * Revision 1.2  2000/03/17 00:12:37  meister
 * Update copyright message
 *
 * Revision 1.1  1998/07/15 20:58:21  sra
 * Initial version.
 *
 */

/* [clearcase]
modification history
-------------------
01a,19apr05,job  update copyright notices
*/


/*
 * Checksum routine for Snark demos.
 * You can almost certainly do better than this in assembly language.
 */

#include <wrn/wm/common/config.h>
#include <wrn/wm/common/glue.h>

#include <wrn/wm/demo/snarklib.h>

#ifndef INSTALL_SNARK_GLUE_CKSUM_ALIGNMENT_KLUDGE
#define INSTALL_SNARK_GLUE_CKSUM_ALIGNMENT_KLUDGE defined(__sparc__)
#endif

#if INSTALL_ATTACHE

/*
 * This code is borrowed from RFC 1071. Note that our checksum function
 * takes the number of words as an argument, rather than the number of
 * bytes. Also, we let the caller perform the one's complement change.
 */
bits16_t glue_cksum(bits16_t *addr, unsigned count)
{
  register bits32_t sum = 0;
  
#if INSTALL_SNARK_GLUE_CKSUM_ALIGNMENT_KLUDGE
  /*
   * Kludge around alignment restrictions.
   */
  if (count > 0 && (((unsigned long) addr) & 1) != 0) {
    bits8_t *a = (bits8_t *) addr;
    sum = glue_cksum((bits16_t *) (a+1), count - 1);
    sum = ((sum << 8) & 0xFF00) | ((sum >> 8) & 0x00FF);
    sum += ((a[0] << 8) + a[count * 2 - 1]);
    count = 0;
  }
#endif

  while (count-- > 0)
    sum += *addr++;
  sum  = (sum >> 16) + (sum & 0xFFFF);	/* This can only wrap twice */
  return (sum >> 16) + (sum & 0xFFFF);
}

#endif /* INSTALL_ATTACHE */