def cal_crc8(data):
    '''
    计算1字节数据的CRC8
    '''
    crc = data
    poly = 0x31 #0x07    # 多项式x^8 + x^2 + x^1 + 1，即0x107，（根据原理）省略了最高位1而得0x07
    for i in range(8,0,-1):
        if ((crc & 0x80) >> 7) == 1:    # 判断最高位是否为1，如果是需要异或，否则仅左移
            crc = (crc << 1) ^ poly
        else:
            crc = (crc << 1)
    return crc & 0xFF    # 计算后需要进行截取
 
def crc8(datas):
    '''
    计算数据的CRC8校验码
    '''
    length = len(datas)
    crc = 0x00
    for i in range(length):
        if i == 0:
            crc = cal_crc8(datas[0])     # 先计算第1个数据的CRC8
        else:
            crc = (crc ^ datas[i]) & 0xFF    # 其余的均将上次的CRC8结果与本次数据异或
            crc = cal_crc8(crc)               # 再计算CRC8
    return crc & 0xFF
 
def crc16(datas):
    crc = 0xFFFF
    for pos in datas:
            crc ^= pos
            for i in range(8):
                    if((crc & 1) != 0):
                            crc >>= 1
                            crc ^= 0xA001
                    else:
                            crc >>= 1
    # return ((crc & 0xff) << 8) + (crc >> 8)
    return crc

def add8(datas):
    crc = 0x00
    for data in datas:
        crc = crc + data
    return crc&0xFF

def checkValue_Tbus(data: bytes) -> int:
    crc = 0xFFFF
    length = len(data)
    if length % 2 != 0:
        return 0
    for i in range(0, length, 2):
        val = data[i] * 256 + data[i + 1]
        crc = crc ^ val
    return crc