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tmxtime.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2010 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * Glenn Fowler
 * AT&T Research
 *
 * Time_t conversion support
 */

#include <tmx.h>

#include "FEATURE/tmlib"

/*
 * convert Tm_t to Time_t
 *
 * if west==TM_LOCALZONE then the local timezone is used
 * otherwise west is the number of minutes west
 * of GMT with DST taken into account
 *
 * this routine works with a copy of Tm_t to avoid clashes
 * with other tm*() that may return static Tm_t*
 */

Time_t
tmxtime(register Tm_t* tm, int west)
{
      register Time_t         t;
      register Tm_leap_t*     lp;
      register int32_t  y;
      int               n;
      int               sec;
      time_t                  now;
      struct tm*        tl;
      Tm_t*             to;
      Tm_t              ts;

      ts = *tm;
      to = tm;
      tm = &ts;
      tmset(tm_info.zone);
      tmfix(tm);
      y = tm->tm_year;
      if (y < 69 || y > (TMX_MAXYEAR - 1900))
            return TMX_NOTIME;
      y--;
      t = y * 365 + y / 4 - y / 100 + (y + (1900 - 1600)) / 400 - (1970 - 1901) * 365 - (1970 - 1901) / 4;
      if ((n = tm->tm_mon) > 11)
            n = 11;
      y += 1901;
      if (n > 1 && tmisleapyear(y))
            t++;
      t += tm_data.sum[n] + tm->tm_mday - 1;
      t *= 24;
      t += tm->tm_hour;
      t *= 60;
      t += tm->tm_min;
      t *= 60;
      t += sec = tm->tm_sec;
      if (west != TM_UTCZONE && !(tm_info.flags & TM_UTC))
      {
            /*
             * time zone adjustments
             */

            if (west == TM_LOCALZONE)
            {
                  t += tm_info.zone->west * 60;
                  if (!tm_info.zone->daylight)
                        tm->tm_isdst = 0;
                  else
                  {
                        y = tm->tm_year;
                        tm->tm_year = tmequiv(tm) - 1900;
                        now = tmxsec(tmxtime(tm, tm_info.zone->west));
                        tm->tm_year = y;
                        if (!(tl = tmlocaltime(&now)))
                              return TMX_NOTIME;
                        if (tm->tm_isdst = tl->tm_isdst)
                              t += tm_info.zone->dst * 60;
                  }
            }
            else
            {
                  t += west * 60;
                  if (!tm_info.zone->daylight)
                        tm->tm_isdst = 0;
                  else if (tm->tm_isdst < 0)
                  {
                        y = tm->tm_year;
                        tm->tm_year = tmequiv(tm) - 1900;
                        tm->tm_isdst = 0;
                        now = tmxsec(tmxtime(tm, tm_info.zone->west));
                        tm->tm_year = y;
                        if (!(tl = tmlocaltime(&now)))
                              return TMX_NOTIME;
                        tm->tm_isdst = tl->tm_isdst;
                  }
            }
      }
      else if (tm->tm_isdst)
            tm->tm_isdst = 0;
      *to = *tm;
      if (tm_info.flags & TM_LEAP)
      {
            /*
             * leap second adjustments
             */

            for (lp = &tm_data.leap[0]; t < lp->time - (lp+1)->total; lp++);
            t += lp->total;
            n = lp->total - (lp+1)->total;
            if (t <= (lp->time + n) && (n > 0 && sec > 59 || n < 0 && sec > (59 + n) && sec <= 59))
                  t -= n;
      }
      return tmxsns(t, tm->tm_nsec);
}

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