timeconvert.txt

//+ for datetime convert
#define SECOND_OF_DAY   86400
#define IS_LEAP_YEAR(y) ((y)%4 == 0 && (y)%100 != 0 || (y)%400 == 0)
#define BASE_YEAR       2018 // 1970 2018
static uint8_t DayOfMon[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

void DateTime2UnixTimeStamp(uint32_t *timestamp, RTC_Calendar_t *calendar)
{
    uint16_t year, mon, day, hour, min, sec, i;
    uint32_t nday = 0;

    year = calendar->uwYear ;
    mon  = calendar->ubMonth;
    day  = calendar->ubDate ;
    hour = calendar->ubHour ;
    min  = calendar->ubMin  ;
    sec  = calendar->ubSec  ;

    for (i=BASE_YEAR; i<year; i++) {
        nday += IS_LEAP_YEAR(i) ? 366 : 365;
    }
    for (i=1; i<mon; i++) {
        nday += DayOfMon[i-1] + (i==2 && IS_LEAP_YEAR(year));
    }
    nday += (day - 1);
    *timestamp = nday*SECOND_OF_DAY + (uint32_t)hour*3600 + (uint32_t)min*60 + sec;
}

void UnixTimeStamp2DateTime(RTC_Calendar_t *calendar, uint32_t timestamp)
{
    uint32_t lsec = timestamp, lday;
    lday = timestamp / SECOND_OF_DAY;
    lsec = timestamp % SECOND_OF_DAY;
    uint16_t i, j, iday;

    i = BASE_YEAR;
    while (lday >= IS_LEAP_YEAR(i) ? 366 : 365) {
        lday -= IS_LEAP_YEAR(i) ? 366 : 365;
        i++;
    }

    for (j=0; j<12; j++) {
        iday = DayOfMon[j] + (j==1 && IS_LEAP_YEAR(i));
        if (lday >= iday) lday -= iday;
        else break;
    }

    calendar->uwYear = i;
    calendar->ubMonth= j    + 1;
    calendar->ubDate = lday + 1;
    calendar->ubHour = (lsec / 3600) % 24;
    calendar->ubMin  = (lsec % 3600) / 60;
    calendar->ubSec  = (lsec % 3600) % 60;
}

static int8_t is_dst_day(uint16_t year, uint32_t timestamp)
{
    static uint16_t check_year  = 0;
    static uint32_t check_start = 0;
    static uint32_t check_end   = 0;

    if (check_year != year) {
        RTC_Calendar_t calendar = { year, 1, 1, 2, 0, 0};
        int8_t         dayofweek;
        uint32_t       ts;

        calendar.ubMonth = 3;
        calendar.ubDate  = 1;
        DateTime2UnixTimeStamp(&ts, &calendar);
        dayofweek = (ts / (60 * 60 * 24)) % 7;
        calendar.ubDate  = 6 - dayofweek + 1 + 7;
        DateTime2UnixTimeStamp(&check_start, &calendar);

        calendar.ubMonth = 11;
        calendar.ubDate  = 1;
        DateTime2UnixTimeStamp(&ts, &calendar);
        dayofweek = (ts / (60 * 60 * 24)) % 7;
        calendar.ubDate  = 6 - dayofweek + 1 + 0;
        DateTime2UnixTimeStamp(&check_end  , &calendar);

        check_year = year;
    }

    return timestamp >= check_start && timestamp < check_end;
}
//- for datetime convert