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- /*
- * 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.
- *
- */
- /** \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;
- }
- /*---------------------------------------------------------------------------*/
- unsigned short
- crc16_data(const unsigned char *data, int len, unsigned short acc)
- {
- int i;
-
- for(i = 0; i < len; ++i) {
- acc = crc16_add(*data, acc);
- ++data;
- }
- return acc;
- }
- /*---------------------------------------------------------------------------*/
- /** @} */
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