#include "datetime.h"

/* roughly 100x faster than mktime() */

datetime_sec datetime_untai(dt)

struct datetime *dt;

{

  int year;

  int day;

  int mon;

  year = dt->year + 1900;

  mon = dt->mon;

  if (mon >= 2) { mon -= 2; }

  else { mon += 10; --year; }

  day = (dt->mday - 1) * 10 + 5 + 306 * mon;

  day /= 10;

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

  else { day += 365 * (year % 4); }

  year /= 4;

  day += 1461 * (year % 25);

  year /= 25;

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

  else { day += 36524 * (year % 4); }

  year /= 4;

  day += 146097 * (year - 5);

  day += 11017;

  return ((day * 24 + dt->hour) * 60 + dt->min) * 60 + dt->sec;

}