MicroAPRS/bertos/algo/crc.h

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2014-05-29 03:47:49 -06:00
/**
* \file
* <!--
* This file is part of BeRTOS.
*
* Bertos is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* As a special exception, you may use this file as part of a free software
* library without restriction. Specifically, if other files instantiate
* templates or use macros or inline functions from this file, or you compile
* this file and link it with other files to produce an executable, this
* file does not by itself cause the resulting executable to be covered by
* the GNU General Public License. This exception does not however
* invalidate any other reasons why the executable file might be covered by
* the GNU General Public License.
*
* Copyright 2003, 2004 Develer S.r.l. (http://www.develer.com/)
* Copyright 1999 Bernie Innocenti <bernie@codewiz.org>
*
* -->
*
* \brief Cyclic Redundancy Check 16 (CRC). This algorithm is the one used by the XMODEM protocol.
*
* \note This algorithm is incompatible with the CCITT-CRC16.
*
* This code is based on the article Copyright 1986 Stephen Satchell.
*
* Programmers may incorporate any or all code into their programs,
* giving proper credit within the source. Publication of the
* source routines is permitted so long as proper credit is given
* to Stephen Satchell, Satchell Evaluations and Chuck Forsberg,
* Omen Technology.
*
* \author Bernie Innocenti <bernie@codewiz.org>
*
* $WIZ$ module_name = "crc16"
*/
#ifndef ALGO_CRC_H
#define ALGO_CRC_H
#include "cfg/cfg_arch.h"
#include <cfg/compiler.h>
#include <cpu/pgm.h>
EXTERN_C_BEGIN
/* CRC table */
extern const uint16_t crc16tab[256];
/**
* \brief Compute the updated CRC16 value for one octet (macro version)
*
* \note This version is only intended for old/broken compilers.
* Use the inline function in new code.
*
* \param c New octet (range 0-255)
* \param oldcrc Previous CRC16 value (referenced twice, beware of side effects)
*/
#if CPU_HARVARD && !(defined(ARCH_BOOT) && (ARCH & ARCH_BOOT))
#define UPDCRC16(c, oldcrc) (pgm_read_uint16_t(&crc16tab[((oldcrc) >> 8) ^ ((unsigned char)(c))]) ^ ((oldcrc) << 8))
#else
#define UPDCRC16(c, oldcrc) ((crc16tab[((oldcrc) >> 8) ^ ((unsigned char)(c))]) ^ ((oldcrc) << 8))
#endif
/** CRC-16 init value */
#define CRC16_INIT_VAL ((uint16_t)0)
#ifdef INLINE
/**
* \brief Compute the updated CRC16 value for one octet (inline version)
*/
INLINE uint16_t updcrc16(uint8_t c, uint16_t oldcrc)
{
#if CPU_HARVARD && !(defined(ARCH_BOOT) && (ARCH & ARCH_BOOT))
return pgm_read_uint16_t(&crc16tab[(oldcrc >> 8) ^ c]) ^ (oldcrc << 8);
#else
return crc16tab[(oldcrc >> 8) ^ c] ^ (oldcrc << 8);
#endif
}
#endif // INLINE
/**
* This function implements the CRC 16 calculation on a buffer.
*
* \param crc Current CRC16 value.
* \param buf The buffer to perform CRC calculation on.
* \param len The length of the Buffer.
*
* \return The updated CRC16 value.
*/
extern uint16_t crc16(uint16_t crc, const void *buf, size_t len);
int crc_testSetup(void);
int crc_testRun(void);
int crc_testTearDown(void);
EXTERN_C_END
#endif /* ALGO_CRC_H */