crc8lut.cpp

ti-Chipcon CC1010 1G以下Soc源码库。包括rf,powermodes,clockmodes,flashRW,interrupts,timer,pwm,uart...所有底层驱动源码

/*****************************************************************************
 *                                                                           *
 *        **********                                                         *
 *       ************                                                        *
 *      ***        ***                                                       *
 *      ***   +++   ***                                                      *
 *      ***   + +   ***                                                      *
 *      ***   +                            CHIPCON CC1010                    *
 *      ***   + +   ***                  CRC8 Look Up Table                  *
 *      ***   +++   ***                                                      *
 *      ***       ***                                                        *
 *       ***********                                                         *
 *        *********                                                          *
 *                                                                           *
 *****************************************************************************
 *                                                                           *
 *****************************************************************************
 * Author:              JOL                                                  *
 *****************************************************************************
 * Revision history:                                                         *
 *                                                                           *
 * $Log: CRC8LUT.cpp,v $
 * Revision 1.1  2002/10/14 12:26:36  tos
 * Initial version in CVS.
 *
 *                                                                           *
 ****************************************************************************/

#include "stdafx.h"
#include <stdio.h>

typedef unsigned char byte;
typedef unsigned short word;

#define CRC8_POLY 0x18

// CRC8 LUT
byte crc8LUT[256];




//----------------------------------------------------------------------------
//	byte CRC8Small(byte crcData, byte crcReg)
//
//	Description:
//		A CRC-8 (DOW) implementation optimized for small code size.
//		The function should be called once for each byte in the data
//		the CRC is to be performed on. For the invocation on the first byte
//		the value CRC8_INIT should be given for _crcReg_. The value returned
//		is the CRC-8 of the data supplied so far. This CRC-value should be
//		added at the end of the data to facilitate a later CRC check. During
//		checking the check should be performed on all the data AND the CRC-16
//		value appended to it. The data is intact if the value returned is 0.
//
//	Arguments:
//		byte crcData
//			The data to perform the CRC-8 operation on.
//		byte crcReg
//			The current value of the CRC register. For the first byte the
//			value CRC8_INIT should be supplied. For each additional byte the
//			value returned for the last invocation should be supplied.
//
//	Return value:
//		The updated value of the CRC8 register. This corresponds to the 
//		CRC-8 of the data supplied so far. During CRC checking, after working
//		through all the data and the appended CRC-8 value, the value will be
//		0 if the data is intact.
//----------------------------------------------------------------------------
byte CRC8Small(byte crcData, byte crcReg) {
	int i;

	for (i=0; i<8; i++) {
		if ( (crcReg&0x80) ^ (crcData&0x80) )
			crcReg=(crcReg<<1)^CRC8_POLY;
		else
			crcReg=(crcReg<<1);
		crcData<<=1;
	}
	return crcReg;
} // CRC8Small




//----------------------------------------------------------------------------
//	void createCrc8LutFile(const char* fileName)
//
//	Description:
//		A helper function used to initialize the CRC look-up table used
//		by the CUL FAST_CRC8(...) macro. The function dumps the initialized 
//		table in C-syntax to a file so that they can be included in a source 
//		file. 
//
//	Arguments:
//		const char* fileName
//			The name of a file to receive the initialized tables in C-syntax
//			or NULL to perform table initialization only.
//
//	Return value:
//		void
//----------------------------------------------------------------------------
void createCrc8LutFile(char* fileName) {
    int i;
    FILE *f;

	// Precalculate the LUTs.
    for (i = 0; i < 256; i++) {
		crc8LUT[i] = CRC8Small(0, i);
    }
    
    // Write the tables to a file
    if (!fileName) return;
	if ((f = fopen(fileName, "wt")) == NULL) return;

    fprintf(f, "// CRC8 LUT (newCRC = crc8LUT[dataByte ^ oldCRC])\nbyte code crc8LUT[256] = {\n    ");

    for (i=0; i<256; i++) {
        fprintf(f, "0x%02X%s", crc8LUT[i], (i==255) ? "\n};\n\n" : (i%8==7) ? ",\n    " : ", ");
    }

    fclose(f);
} // createCRC8LUT




//----------------------------------------------------------------------------
//	MAIN PROGRAM
//----------------------------------------------------------------------------
int main(int argc, char* argv[]) {
    createCrc8LutFile("CRC8LUT.txt");
         
	return 0;
} // main