lib/ansi/gmtime.c

   1 /*
   2  * gmtime - convert the calendar time into broken down time
   3  */
   4 /* $Header$ */
   5
   6 #include        <time.h>
   7 #include        <limits.h>
   8 #include        "loc_time.h"
   9
  10 struct tm *
  11 gmtime(register const time_t *timer)
  12 {
  13         static struct tm br_time;
  14         register struct tm *timep = &br_time;
  15         time_t time = *timer;
  16         register unsigned long dayclock, dayno;
  17         int year = EPOCH_YR;
  18
  19         dayclock = (unsigned long)time % SECS_DAY;
  20         dayno = (unsigned long)time / SECS_DAY;
  21
  22         timep->tm_sec = dayclock % 60;
  23         timep->tm_min = (dayclock % 3600) / 60;
  24         timep->tm_hour = dayclock / 3600;
  25         timep->tm_wday = (dayno + 4) % 7;       /* day 0 was a thursday */
  26         while (dayno >= YEARSIZE(year)) {
  27                 dayno -= YEARSIZE(year);
  28                 year++;
  29         }
  30         timep->tm_year = year - YEAR0;
  31         timep->tm_yday = dayno;
  32         timep->tm_mon = 0;
  33         while (dayno >= _ytab[LEAPYEAR(year)][timep->tm_mon]) {
  34                 dayno -= _ytab[LEAPYEAR(year)][timep->tm_mon];
  35                 timep->tm_mon++;
  36         }
  37         timep->tm_mday = dayno + 1;
  38         timep->tm_isdst = 0;
  39
  40         return timep;
  41 }