( M0P_RTC->CR0 & 0x7faf ) !=0x4188 与( M0P_RTC->CR0 & 0x4188 ) !=0x4188的区别 
if((M0P_RTC-CR0&0x7faf)!=0x4188)中为什么不写成if((M0P_RTC-CR0&0x4188)!=0x4188)(M0P_RTC-CR0&0x7faf)!=0x4188与(M0P_RTC-CR0&0x4188 )0x7faf==》0111111110101111|||||||||||||要判断的位0x