openbios/openboot/tools/checksum/checksum.c

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• Hash : 1a08f436
  Author :
  Date : 2010-08-25T09:23:17
  

  change to well-formed svn directory structure. git-svn-id: svn://coreboot.org/openboot/trunk@2 4486e004-3823-0410-90c7-fb508cc143bb

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• tools/checksum/checksum.c

• /*
  * ========== Copyright Header Begin ==========================================
  *
  * Hypervisor Software File: checksum.c
  * 
  * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
  * 
  *  - Do no alter or remove copyright notices
  * 
  *  - Redistribution and use of this software in source and binary forms, with 
  *    or without modification, are permitted provided that the following 
  *    conditions are met: 
  * 
  *  - Redistribution of source code must retain the above copyright notice, 
  *    this list of conditions and the following disclaimer.
  * 
  *  - Redistribution 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. 
  * 
  *    Neither the name of Sun Microsystems, Inc. or the names of contributors 
  * may be used to endorse or promote products derived from this software 
  * without specific prior written permission. 
  * 
  *     This software is provided "AS IS," without a warranty of any kind. 
  * ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, 
  * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A 
  * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN 
  * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR 
  * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR 
  * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN 
  * OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR 
  * FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE 
  * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, 
  * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF 
  * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  * 
  * You acknowledge that this software is not designed, licensed or
  * intended for use in the design, construction, operation or maintenance of
  * any nuclear facility. 
  * 
  * ========== Copyright Header End ============================================
  */
  /*
   * id: @(#)checksum.c 1.9 01/03/04
   * purpose: Flash PROM Update Utility
   * copyright: Copyright 1995-2001 Sun Microsystems, Inc. All Rights Reserved
  */
  
  #include <sys/types.h>
  
  uint16_t
  checksum(uint16_t *addr, int32_t count)
  {
  
  	/*
  	 * Compute Internet Checksum for "count" bytes beginning at
  	 * location "addr".
  	 */
  	register uint32_t sum = 0;
  
  	while (count > 1) {
  		/* This is the inner loop */
  		sum += *addr++;
  		count -= 2;
  	}
  
  	/* Add left-over byte, if any */
  	if (count > 0)
  		sum += *(unsigned char *) addr;
  
  	/* Fold 32-bit sum to 16 bits */
  	while (sum >> 16) {
  		sum = (sum & 0xffff) + (sum >> 16);
  	}
  
  	sum = (~sum) & 0xffff;
  	if (sum == 0)
  		sum = 0xffff;
  	return (sum);
  }
  

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