/* 19950925 */
#include "datetime.h"

void datetime_tai(dt,t)
struct datetime *dt;
datetime_sec t;
{
 int day;
 int tod;
 int year;
 int yday;
 int wday;
 int mon;

 tod = t % 86400;
 day = t / 86400;
 if (tod < 0) { tod += 86400; --day; }

 dt->hour = tod / 3600;
 tod %= 3600;
 dt->min = tod / 60;
 dt->sec = tod % 60;

 wday = (day + 4) % 7; if (wday < 0) wday += 7;
 dt->wday = wday;

 day -= 11017;
 /* day 0 is march 1, 2000 */
 year = 5 + day / 146097;
 day = day % 146097; if (day < 0) { day += 146097; --year; }
 /* from now on, day is nonnegative */
 year *= 4;
 if (day == 146096) { year += 3; day = 36524; }
 else { year += day / 36524; day %= 36524; }
 year *= 25;
 year += day / 1461;
 day %= 1461;
 year *= 4;
 yday = (day < 306);
 if (day == 1460) { year += 3; day = 365; }
 else { year += day / 365; day %= 365; }
 yday += day;

 day *= 10;
 mon = (day + 5) / 306;
 day = day + 5 - 306 * mon;
 day /= 10;
 if (mon >= 10) { yday -= 306; ++year; mon -= 10; }
 else { yday += 59; mon += 2; }

 dt->yday = yday;
 dt->year = year - 1900;
 dt->mon = mon;
 dt->mday = day + 1;
}