说明：  Keil C51 上51系列单片机优化的CRC－8 算法。可以自己改其他算式的，包含字节查表，半字节查表，bit计算。很难得的哦。
(Keil C51 on the 51 computers optimized CRC-8 algorithm. Other formula can do it ourselves, and look-up table contains the byte, half-byte look-up table, bit computing. Hard to come by Oh.)