59 lines
2.4 KiB
Java
59 lines
2.4 KiB
Java
/*
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* Copyright (c) 2007, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: CRCCoder.java,v 1.1 2009/11/10 12:54:39 joxe Exp $
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*/
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package se.sics.cooja.emulatedmote;
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import org.apache.log4j.Logger;
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/**
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* Ported from contiki-2.x/core/lib/crc16.[ch].
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*
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* @author Fredrik Osterlind
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*/
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public class CRCCoder {
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private static Logger logger = Logger.getLogger(CRCCoder.class);
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/**
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* Updates given accumulated CRC16 checksum with given byte.
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*
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* @param b Byte to be added to CRC
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* @param acc Accumulated CRC that is to be updated
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* @return New accumulated CRC
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*/
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public static short crc16Add(byte b, short acc) {
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acc ^= 0xff & b;
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acc = (short) ((0xff & (acc >> 8)) | (0xff00 & (acc << 8)));
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acc ^= 0xffff & ((acc & 0xff00) << 4);
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acc ^= (0xffff & (0xff & (acc >> 8)) >> 4);
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acc ^= 0xffff & ((0xffff & (acc & 0xff00)) >>> 5);
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return acc;
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}
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} |