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