RTC_MON_SHIFT
*st_time = ((tm->tm_mon + 1) << RTC_MON_SHIFT)
tm->tm_mon = ((st_time & RTC_MON_MASK) >> RTC_MON_SHIFT) - 1;
#define RTC_MON_MASK (0xF << RTC_MON_SHIFT) /* Month [1-12] 1=January */