3 /* roughly 100x faster than mktime() */
4 datetime_sec datetime_untai(dt)
11 year = dt->year + 1900;
14 if (mon >= 2) { mon -= 2; }
15 else { mon += 10; --year; }
17 day = (dt->mday - 1) * 10 + 5 + 306 * mon;
20 if (day == 365) { year -= 3; day = 1460; }
21 else { day += 365 * (year % 4); }
24 day += 1461 * (year % 25);
27 if (day == 36524) { year -= 3; day = 146096; }
28 else { day += 36524 * (year % 4); }
31 day += 146097 * (year - 5);
34 return ((day * 24 + dt->hour) * 60 + dt->min) * 60 + dt->sec;