117 lines
3.8 KiB
C
117 lines
3.8 KiB
C
/*
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* Copyright (c) 2005, 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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* This file is part of the Contiki operating system.
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*
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* @(#)$Id: me.c,v 1.1 2006/06/17 22:41:18 adamdunkels Exp $
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*/
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/** \addtogroup me
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* @{ */
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/**
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* \file
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* Implementation of the table-driven Manchester encoding and decoding.
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* \author
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* Adam Dunkels <adam@sics.se>
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*/
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#include "me_tabs.h"
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/*---------------------------------------------------------------------------*/
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/**
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* Manchester encode an 8-bit byte.
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*
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* This function Manchester encodes an 8-bit byte into a 16-bit
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* word. The function me_decode() does the inverse operation.
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*
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* \param c The byte to be encoded
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*
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* \retval The encoded word.
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*/
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/*---------------------------------------------------------------------------*/
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unsigned short
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me_encode(unsigned char c)
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{
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return me_encode_tab[c];
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Decode a Manchester encoded 16-bit word.
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*
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* This function decodes a Manchester encoded 16-bit word into a 8-bit
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* byte. The function does not check for parity errors in the encoded
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* byte.
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*
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* \param m The 16-bit Manchester encoded word
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* \return The decoded 8-bit byte
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*/
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/*---------------------------------------------------------------------------*/
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unsigned char
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me_decode16(unsigned short m)
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{
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unsigned char m1, m2, c;
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m1 = m >> 8;
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m2 = m & 0xff;
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c = (me_decode_tab[m1] << 4) |
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me_decode_tab[m2];
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return c;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Decode a Manchester encoded 8-bit byte.
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*
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* This function decodes a Manchester encoded 8-bit byte into 4
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* decoded bits.. The function does not check for parity errors in the
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* encoded byte.
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*
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* \param m The 8-bit Manchester encoded byte
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* \return The decoded 4 bits
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*/
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/*---------------------------------------------------------------------------*/
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unsigned char
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me_decode8(unsigned char m)
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{
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return me_decode_tab[m];
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Check if an encoded byte is valid.
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*/
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/*---------------------------------------------------------------------------*/
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unsigned char
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me_valid(unsigned char m)
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{
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return me_valid_tab[m];
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}
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/*---------------------------------------------------------------------------*/
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/** @} */
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