项目综合

INT16U cal_crc_half(INT8U far *pin, INT8U len)

{

	INT16U crc;

	INT8U da;

	INT8U far *ptr;

	INT8U bCRCHign;

    INT8U bCRCLow;

	INT16U crc_ta[16]=

	{ /* CRC??ʽ?? */

		0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,

		0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef

	};

	ptr=pin;

	crc=0;

	while(len--!=0) 

	{

		da=((INT8U)(crc>>8))>>4; /* ?ݴ?CRC?ĸ???λ */

		crc<<=4; /* CRC????4λ???൱??ȡCRC?ĵ?12λ??*/

		crc^=crc_ta[da^(*ptr>>4)]; /* CRC?ĸ?4λ?ͱ??ֽڵ?ǰ???ֽ???Ӻ???????CRC??Ȼ???????һ??CRC?????? */

		da=((INT8U)(crc>>8))>>4; /* ?ݴ?CRC?ĸ?4λ */

		crc<<=4; /* CRC????4λ?? ?൱??CRC?ĵ?12λ?? */

		crc^=crc_ta[da^(*ptr&0x0f)]; /* CRC?ĸ?4λ?ͱ??ֽڵĺ???ֽ???Ӻ???????CRC??Ȼ???ټ?????һ??CRC?????? */

		ptr++;

	}

	bCRCLow = crc;

    bCRCHign= (INT8U)(crc>>8);

	if(bCRCLow==0x28||bCRCLow==0x0d||bCRCLow==0x0a)

    {

    	bCRCLow++;

    }

    if(bCRCHign==0x28||bCRCHign==0x0d||bCRCHign==0x0a)

    {

		bCRCHign++;

    }

    crc = ((INT16U)bCRCHign)<<8;

    crc += bCRCLow;

	return(crc);

}