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def calc_crc16(binary_data, crc=0xffff):
    """
    Calculates CRC16 on binary_data

    :param int crc: CRC value to start calculation with
    :param bytearray binary_data: Array with data to run CRC16 calculation on
    :return int: Calculated CRC value of binary_data
    """

    for b in binary_data:
        crc = (crc >> 8 & 0x00FF) | (crc << 8 & 0xFF00)
        crc ^= ord(b)
        crc ^= (crc & 0x00FF) >> 4
        crc ^= (crc << 8) << 4
        crc ^= ((crc & 0x00FF) << 4) << 1
    return crc & 0xFFFF