1 /* 19950925 */

     2 #include "datetime.h"

     3 

     4 void datetime_tai(dt,t)

     5 struct datetime *dt;

     6 datetime_sec t;

     7 {

     8   int day;

     9   int tod;

    10   int year;

    11   int yday;

    12   int wday;

    13   int mon;

    14  

    15   tod = t % 86400;

    16   day = t / 86400;

    17   if (tod < 0) { tod += 86400; --day; }

    18  

    19   dt->hour = tod / 3600;

    20   tod %= 3600;

    21   dt->min = tod / 60;

    22   dt->sec = tod % 60;

    23  

    24   wday = (day + 4) % 7; if (wday < 0) wday += 7;

    25   dt->wday = wday;

    26  

    27   day -= 11017;

    28   /* day 0 is march 1, 2000 */

    29   year = 5 + day / 146097;

    30   day = day % 146097; if (day < 0) { day += 146097; --year; }

    31   /* from now on, day is nonnegative */

    32   year *= 4;

    33   if (day == 146096) { year += 3; day = 36524; }

    34   else { year += day / 36524; day %= 36524; }

    35   year *= 25;

    36   year += day / 1461;

    37   day %= 1461;

    38   year *= 4;

    39   yday = (day < 306);

    40   if (day == 1460) { year += 3; day = 365; }

    41   else { year += day / 365; day %= 365; }

    42   yday += day;

    43  

    44   day *= 10;

    45   mon = (day + 5) / 306;

    46   day = day + 5 - 306 * mon;

    47   day /= 10;

    48   if (mon >= 10) { yday -= 306; ++year; mon -= 10; }

    49   else { yday += 59; mon += 2; }

    50  

    51   dt->yday = yday;

    52   dt->year = year - 1900;

    53   dt->mon = mon;

    54   dt->mday = day + 1;

    55 }