mirror of
https://github.com/oliverschmidt/contiki.git
synced 2024-08-18 05:29:29 +00:00
118 lines
3.8 KiB
C
118 lines
3.8 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: 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];
|
||
|
}
|
||
|
/*---------------------------------------------------------------------------*/
|
||
|
|
||
|
/** @} */
|
||
|
|