说明：  CRC即循环冗余校验码（Cyclic Redundancy CRC是数据通信领域中最常用的一种差错校验码，其特征是信息字段和校验字段的长度可以任意选定。
(CRC is cyclic redundancy check code (Cyclic Redundancy CRC is the most commonly used data communications, an error check code, characterized by the information field and check the length of the field can be arbitrarily selected.)