crc_16.cpp

file img CRC 16 function

// crc_16.cpp : 能贾 览侩 橇肺弊伐俊 措茄 柳涝痢阑 沥狼钦聪促.
//

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

typedef unsigned short int  INT16U;
typedef unsigned char INT8U;

#define MAX_STRING_SIZE	2048

INT16U calc_crc16(INT8U *buff, long length);



INT16U crctblp[256] = 
{ 
	0x0000,0x1021,0x2042,0x3063,0x4084,0x50A5,0x60C6,0x70E7,
	0x8108,0x9129,0xA14A,0xB16B,0xC18C,0xD1AD,0xE1CE,0xF1EF,
	0x1231,0x0210,0x3273,0x2252,0x52B5,0x4294,0x72F7,0x62D6,
	0x9339,0x8318,0xB37B,0xA35A,0xD3BD,0xC39C,0xF3FF,0xE3DE,
	0x2462,0x3443,0x0420,0x1401,0x64E6,0x74C7,0x44A4,0x5485,
	0xA56A,0xB54B,0x8528,0x9509,0xE5EE,0xF5CF,0xC5AC,0xD58D,
	0x3653,0x2672,0x1611,0x0630,0x76D7,0x66F6,0x5695,0x46B4,
	0xB75B,0xA77A,0x9719,0x8738,0xF7DF,0xE7FE,0xD79D,0xC7BC,
	0x48C4,0x58E5,0x6886,0x78A7,0x0840,0x1861,0x2802,0x3823,
	0xC9CC,0xD9ED,0xE98E,0xF9AF,0x8948,0x9969,0xA90A,0xB92B,
	0x5AF5,0x4AD4,0x7AB7,0x6A96,0x1A71,0x0A50,0x3A33,0x2A12,
	0xDBFD,0xCBDC,0xFBBF,0xEB9E,0x9B79,0x8B58,0xBB3B,0xAB1A,
	0x6CA6,0x7C87,0x4CE4,0x5CC5,0x2C22,0x3C03,0x0C60,0x1C41,
	0xEDAE,0xFD8F,0xCDEC,0xDDCD,0xAD2A,0xBD0B,0x8D68,0x9D49,
	0x7E97,0x6EB6,0x5ED5,0x4EF4,0x3E13,0x2E32,0x1E51,0x0E70,
	0xFF9F,0xEFBE,0xDFDD,0xCFFC,0xBF1B,0xAF3A,0x9F59,0x8F78,
	0x9188,0x81A9,0xB1CA,0xA1EB,0xD10C,0xC12D,0xF14E,0xE16F,
	0x1080,0x00A1,0x30C2,0x20E3,0x5004,0x4025,0x7046,0x6067,
	0x83B9,0x9398,0xA3FB,0xB3DA,0xC33D,0xD31C,0xE37F,0xF35E,
	0x02B1,0x1290,0x22F3,0x32D2,0x4235,0x5214,0x6277,0x7256,
	0xB5EA,0xA5CB,0x95A8,0x8589,0xF56E,0xE54F,0xD52C,0xC50D,
	0x34E2,0x24C3,0x14A0,0x0481,0x7466,0x6447,0x5424,0x4405,
	0xA7DB,0xB7FA,0x8799,0x97B8,0xE75F,0xF77E,0xC71D,0xD73C,
	0x26D3,0x36F2,0x0691,0x16B0,0x6657,0x7676,0x4615,0x5634,
	0xD94C,0xC96D,0xF90E,0xE92F,0x99C8,0x89E9,0xB98A,0xA9AB,
	0x5844,0x4865,0x7806,0x6827,0x18C0,0x08E1,0x3882,0x28A3,
	0xCB7D,0xDB5C,0xEB3F,0xFB1E,0x8BF9,0x9BD8,0xABBB,0xBB9A,
	0x4A75,0x5A54,0x6A37,0x7A16,0x0AF1,0x1AD0,0x2AB3,0x3A92,
	0xFD2E,0xED0F,0xDD6C,0xCD4D,0xBDAA,0xAD8B,0x9DE8,0x8DC9,
	0x7C26,0x6C07,0x5C64,0x4C45,0x3CA2,0x2C83,0x1CE0,0x0CC1,
	0xEF1F,0xFF3E,0xCF5D,0xDF7C,0xAF9B,0xBFBA,0x8FD9,0x9FF8,
	0x6E17,0x7E36,0x4E55,0x5E74,0x2E93,0x3EB2,0x0ED1,0x1EF0 
};

int _tmain(int argc, const char* argv[])
{
	char input_string[MAX_STRING_SIZE];

	INT8U read_ddata[200000];

    char *ptr;

	long file_size,copy_len;

	INT16U crc_chk;

	FILE *fp;

    printf( "\nCRC16 algorithm sample program" );

    printf( "\n\n\nInput: " );
    fgets( input_string, MAX_STRING_SIZE-1, stdin );

    ptr = input_string;
    while ( *ptr  &&  *ptr != '\r'  &&  *ptr != '\n' ) ptr++;
    *ptr = 0;

   if( (fp = fopen( input_string, "rb" )) == NULL ) // C4996
      printf( "The file %s was not opened\n",input_string );
   else
   {
	printf( "The file %s was opened\n",input_string );
	fseek(fp,0,SEEK_END); //场栏肺 啊扼	
	file_size = ftell(fp);
	printf( "The file size : %d \n",file_size );
	
	//fseek(fp,0,SEEK_SET); //贸澜栏肺 啊扼
	rewind(fp);

	for(copy_len =0; copy_len < file_size; copy_len++)
	{
		read_ddata[copy_len] = fgetc(fp);
	}

	crc_chk = calc_crc16(read_ddata, file_size);

	printf( "The file crc dec : %d , hex : %x \n",crc_chk,crc_chk );

	_fcloseall();

   }

	printf( "plese ENTER key !! \n" );
	getchar();

	return 0;
}




INT16U calc_crc16(INT8U *buff, long length)
{
    long i; 
	INT16U accum = 0;
    INT16U comb_val;
	INT8U cnk;

    for(i=0; i<length; i++)
    //for(i=0; i<length; buff++,++i)
	{
		cnk = *(buff+i);
		comb_val = (accum >> 8) ^ cnk;
        accum   = (accum << 8) ^ crctblp[comb_val];
    }

  return accum ;
}