#include "crc16.h"
uint16_t crc16bitbybit(uint8_t *ptr, uint16_t len)
{
	uint8_t i;
	uint16_t crc = 0xffff;
	uint16_t polynom = 0xA001;//CRC校验
	if (len == 0) 
	{
		len = 1;
	}
	while (len--) 
	{
		crc ^= *ptr;
		for (int i = 0; i<8; i++)
		{
			if (crc & 1) 
			{
				crc >>= 1;
				crc ^= polynom;
			}
			else 
			{
				crc >>= 1;
			}
		}
		ptr++;
	}
	return crc;
}