mirror of
https://github.com/oliverschmidt/contiki.git
synced 2024-11-17 21:09:03 +00:00
68 lines
2.4 KiB
C
68 lines
2.4 KiB
C
|
/*
|
||
|
|
* Copyright (c) 2005, Swedish Institute of Computer Science
|
||
|
|
* All rights reserved.
|
||
|
|
*
|
||
|
|
* 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. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
|
||
|
|
*
|
||
|
|
* This file is part of the Contiki operating system.
|
||
|
|
*
|
||
|
|
* @(#)$Id: crc16.c,v 1.1 2006/06/17 22:41:17 adamdunkels Exp $
|
||
|
|
*/
|
||
|
|
|
||
|
|
/** \addtogroup crc16
|
||
|
|
* @{ */
|
||
|
|
|
||
|
|
/**
|
||
|
|
* \file
|
||
|
|
* Implementation of the CRC16 calculcation
|
||
|
|
* \author
|
||
|
|
* Adam Dunkels <adam@sics.se>
|
||
|
|
*
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* CITT CRC16 polynomial ^16 + ^12 + ^5 + 1 */
|
||
|
|
/*---------------------------------------------------------------------------*/
|
||
|
|
unsigned short
|
||
|
|
crc16_add(unsigned char b, unsigned short acc)
|
||
|
|
{
|
||
|
|
/*
|
||
|
|
acc = (unsigned char)(acc >> 8) | (acc << 8);
|
||
|
|
acc ^= b;
|
||
|
|
acc ^= (unsigned char)(acc & 0xff) >> 4;
|
||
|
|
acc ^= (acc << 8) << 4;
|
||
|
|
acc ^= ((acc & 0xff) << 4) << 1;
|
||
|
|
*/
|
||
|
|
|
||
|
|
acc ^= b;
|
||
|
|
acc = (acc >> 8) | (acc << 8);
|
||
|
|
acc ^= (acc & 0xff00) << 4;
|
||
|
|
acc ^= (acc >> 8) >> 4;
|
||
|
|
acc ^= (acc & 0xff00) >> 5;
|
||
|
|
return acc;
|
||
|
|
}
|
||
|
|
/*---------------------------------------------------------------------------*/
|
||
|
|
|
||
|
|
/** @} */
|