crc16.c

15693 hf reader 伟根26接口

#include "typedef.h"
#include "crc16.h"

#define POLYNOMIAL  0x8408   /*x^16+x^12+x^5+1*/
#define PRESET_VALUE 0xFFFF
#define CHECK_VALUE 0xF0B8
#define CALC_CRC     1
#define CHECK_CRC    0

uchar code tab1[16]={0x00,0x08,0x04,0x0c,0x02,0x0a,0x06,0x0e ,0x01,0x09,0x05,0x0d,0x03,0x0b,0x07,0x0f};


WORD crc16Calculate(BYTE idata * pBuf,BYTE byLen)
{
	unsigned int current_crc_value;
	BYTE i,j;
 	current_crc_value = PRESET_VALUE;
 	for(i=0;i<byLen;i++)
  	{
		current_crc_value = current_crc_value^pBuf[i];
		for(j=0;j<8;j++)
		{
			if(current_crc_value & 0x0001)
			{
				current_crc_value = (current_crc_value>>1)^POLYNOMIAL;
			}
			else
			{
				current_crc_value = (current_crc_value>>1);
			}
		}
   	}
	current_crc_value = ~current_crc_value;		//?????
 	return(current_crc_value);
 } 
/******************************************************/
bit chkCRC(BYTE idata * cBuf,BYTE cLen)
{
   bit flag =1;
   uchar i;
   uint j;
   for(i=0;i<cLen;i++) { cBuf[i] = ReflectBYTE(cBuf[i]); }
   j = crc16Calculate(cBuf,cLen-2);
   flag  = (cBuf[cLen-2] == LOBYTE(j) );		//crc LSByte
   flag &= (cBuf[cLen-1] == HIBYTE(j) );		//crc MSByte
   return(flag);
}
/*
bit chkCRC_re(BYTE idata * cBuf,BYTE cLen)
{
   bit flag=1 ;
   uint j;
   j = ~ crc16Calculate(cBuf,cLen-2);
   flag  = (cBuf[cLen-2] == LOBYTE(j) );		//crc MSByte
   flag &= (cBuf[cLen-1] == HIBYTE(j) );		//crc LSByte
   return(flag);
}
*/
BYTE ReflectBYTE(BYTE byOrg) 
{
	BYTE j,k;
	j = byOrg & 0x0f;
	j = tab1[j];
	j = j<<4;
	k = byOrg>>4;
	k = tab1[k];
	j = j + k;
	return(j);
}
/******************************************************/