/* CRC16.C */

/* Developed 1990-1997 by Rob Swindell; PO Box 501, Yorba Linda, CA 92885 */

/* 16-bit CRC routines */

#include <stdint.h>

/****************************************************************************/
/* Updates 16-bit "rcrc" with character 'ch'                                */
/****************************************************************************/
uint16_t Upd_crc16(uint8_t ch, uint16_t poly, uint16_t crc)
{
	uint16_t i, cy;
	uint8_t nch = ch;
 
	for (i=0; i<8; i++)
	{
		cy = crc & 0x8000;
		crc <<= 1;
		if (nch & 0x80)
			crc |= 1;
		
		nch<<=1;
		
		if (cy) 
			crc ^= poly;
	}
	return crc;
}

/****************************************************************************/
/* Returns 16-crc of string (not counting terminating NULL)                 */
/****************************************************************************/
uint16_t Crc16(uint16_t poly, uint16_t crc, uint8_t *pBuf, uint32_t len)
{
	while(len)
	{
		crc = Upd_crc16(*pBuf, poly, crc);
		pBuf++;
		len--;

	}

	return crc;
}