localtime.cc

cygwin, 著名的在win32下模拟unix操作系统的东东

 */
extern "C" struct tm *
gmtime_r(const time_t *timep, struct tm *tm)
{
	gmtsub(timep, 0L, tm);
	return tm;
}

#ifdef STD_INSPIRED

extern "C" struct tm *
offtime(const time_t *timep, const long offset)
{
	gmtsub(timep, offset, &tm);
	return &tm;
}

#endif /* defined STD_INSPIRED */

static void
timesub(const time_t *timep, const long offset, const struct state *sp,
	struct tm *tmp)
{
	register const struct lsinfo *	lp;
	register long			days;
	register long			rem;
	register int			y;
	register int			yleap;
	register const int *		ip;
	register long			corr;
	register int			hit;
	register int			i;

	corr = 0;
	hit = 0;
#ifdef ALL_STATE
	i = (sp == NULL) ? 0 : sp->leapcnt;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
	i = sp->leapcnt;
#endif /* State Farm */
	while (--i >= 0) {
		lp = &sp->lsis[i];
		if (*timep >= lp->ls_trans) {
			if (*timep == lp->ls_trans) {
				hit = ((i == 0 && lp->ls_corr > 0) ||
					lp->ls_corr > sp->lsis[i - 1].ls_corr);
				if (hit)
					while (i > 0 &&
						sp->lsis[i].ls_trans ==
						sp->lsis[i - 1].ls_trans + 1 &&
						sp->lsis[i].ls_corr ==
						sp->lsis[i - 1].ls_corr + 1) {
							++hit;
							--i;
					}
			}
			corr = lp->ls_corr;
			break;
		}
	}
	days = *timep / SECSPERDAY;
	rem = *timep % SECSPERDAY;
#ifdef mc68k
	if (*timep == 0x80000000) {
		/*
		** A 3B1 muffs the division on the most negative number.
		*/
		days = -24855;
		rem = -11648;
	}
#endif /* defined mc68k */
	rem += (offset - corr);
	while (rem < 0) {
		rem += SECSPERDAY;
		--days;
	}
	while (rem >= SECSPERDAY) {
		rem -= SECSPERDAY;
		++days;
	}
	tmp->tm_hour = (int) (rem / SECSPERHOUR);
	rem = rem % SECSPERHOUR;
	tmp->tm_min = (int) (rem / SECSPERMIN);
	/*
	** A positive leap second requires a special
	** representation.  This uses "... ??:59:60" et seq.
	*/
	tmp->tm_sec = (int) (rem % SECSPERMIN) + hit;
	tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
	if (tmp->tm_wday < 0)
		tmp->tm_wday += DAYSPERWEEK;
	y = EPOCH_YEAR;
#define LEAPS_THRU_END_OF(y)	((y) / 4 - (y) / 100 + (y) / 400)
	while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
		register int	newy;

		newy = y + days / DAYSPERNYEAR;
		if (days < 0)
			--newy;
		days -= (newy - y) * DAYSPERNYEAR +
			LEAPS_THRU_END_OF(newy - 1) -
			LEAPS_THRU_END_OF(y - 1);
		y = newy;
	}
	tmp->tm_year = y - TM_YEAR_BASE;
	tmp->tm_yday = (int) days;
	ip = mon_lengths[yleap];
	for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
		days = days - (long) ip[tmp->tm_mon];
	tmp->tm_mday = (int) (days + 1);
	tmp->tm_isdst = 0;
#ifdef TM_GMTOFF
	tmp->TM_GMTOFF = offset;
#endif /* defined TM_GMTOFF */
}

extern "C" char *
ctime(const time_t *timep)
{
/*
** Section 4.12.3.2 of X3.159-1989 requires that
**	The ctime function converts the calendar time pointed to by timer
**	to local time in the form of a string.  It is equivalent to
**		asctime(localtime(timer))
*/
	return asctime(localtime(timep));
}

extern "C" char *
ctime_r(const time_t *timep, char *buf)
{
	struct tm	tm;

	return asctime_r(localtime_r(timep, &tm), buf);
}

/*
** Adapted from code provided by Robert Elz, who writes:
**	The "best" way to do mktime I think is based on an idea of Bob
**	Kridle's (so its said...) from a long time ago.
**	[[e-mail] as of 1996-01-16.]
**	It does a binary search of the time_t space.  Since time_t's are
**	just 32 bits, its a max of 32 iterations (even at 64 bits it
**	would still be very reasonable).
*/

#ifndef WRONG
#define WRONG	(-1)
#endif /* !defined WRONG */

/*
** Simplified normalize logic courtesy Paul Eggert ([e-mail]).
*/

static int
increment_overflow(int *number, int delta)
{
	int	number0;

	number0 = *number;
	*number += delta;
	return (*number < number0) != (delta < 0);
}

static int
normalize_overflow(int *tensptr, int *unitsptr, const int base)
{
	register int	tensdelta;

	tensdelta = (*unitsptr >= 0) ?
		(*unitsptr / base) :
		(-1 - (-1 - *unitsptr) / base);
	*unitsptr -= tensdelta * base;
	return increment_overflow(tensptr, tensdelta);
}

static int
tmcomp(register const struct tm *atmp, register const struct tm *btmp)
{
	register int	result;

	if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
		(result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
		(result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
		(result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
		(result = (atmp->tm_min - btmp->tm_min)) == 0)
			result = atmp->tm_sec - btmp->tm_sec;
	return result;
}

static time_t
time2sub(struct tm *tmp, void (*funcp) P((const time_t*, long, struct tm*)),
	 const long offset, int *okayp, const int do_norm_secs)
{
	register const struct state *	sp;
	register int			dir;
	register int			bits;
	register int			i, j ;
	register int			saved_seconds;
	time_t				newt;
	time_t				t;
	struct tm			yourtm, mytm;

	*okayp = FALSE;
	yourtm = *tmp;
	if (do_norm_secs) {
		if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec,
			SECSPERMIN))
				return WRONG;
	}
	if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
		return WRONG;
	if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
		return WRONG;
	if (normalize_overflow(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR))
		return WRONG;
	/*
	** Turn yourtm.tm_year into an actual year number for now.
	** It is converted back to an offset from TM_YEAR_BASE later.
	*/
	if (increment_overflow(&yourtm.tm_year, TM_YEAR_BASE))
		return WRONG;
	while (yourtm.tm_mday <= 0) {
		if (increment_overflow(&yourtm.tm_year, -1))
			return WRONG;
		i = yourtm.tm_year + (1 < yourtm.tm_mon);
		yourtm.tm_mday += year_lengths[isleap(i)];
	}
	while (yourtm.tm_mday > DAYSPERLYEAR) {
		i = yourtm.tm_year + (1 < yourtm.tm_mon);
		yourtm.tm_mday -= year_lengths[isleap(i)];
		if (increment_overflow(&yourtm.tm_year, 1))
			return WRONG;
	}
	for ( ; ; ) {
		i = mon_lengths[isleap(yourtm.tm_year)][yourtm.tm_mon];
		if (yourtm.tm_mday <= i)
			break;
		yourtm.tm_mday -= i;
		if (++yourtm.tm_mon >= MONSPERYEAR) {
			yourtm.tm_mon = 0;
			if (increment_overflow(&yourtm.tm_year, 1))
				return WRONG;
		}
	}
	if (increment_overflow(&yourtm.tm_year, -TM_YEAR_BASE))
		return WRONG;
	if (yourtm.tm_year + TM_YEAR_BASE < EPOCH_YEAR) {
		/*
		** We can't set tm_sec to 0, because that might push the
		** time below the minimum representable time.
		** Set tm_sec to 59 instead.
		** This assumes that the minimum representable time is
		** not in the same minute that a leap second was deleted from,
		** which is a safer assumption than using 58 would be.
		*/
		if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
			return WRONG;
		saved_seconds = yourtm.tm_sec;
		yourtm.tm_sec = SECSPERMIN - 1;
	} else {
		saved_seconds = yourtm.tm_sec;
		yourtm.tm_sec = 0;
	}
	/*
	** Divide the search space in half
	** (this works whether time_t is signed or unsigned).
	*/
	bits = TYPE_BIT(time_t) - 1;
	/*
	** If time_t is signed, then 0 is just above the median,
	** assuming two's complement arithmetic.
	** If time_t is unsigned, then (1 << bits) is just above the median.
	*/
	t = TYPE_SIGNED(time_t) ? 0 : (((time_t) 1) << bits);
	for ( ; ; ) {
		(*funcp)(&t, offset, &mytm);
		dir = tmcomp(&mytm, &yourtm);
		if (dir != 0) {
			if (bits-- < 0)
				return WRONG;
			if (bits < 0)
				--t; /* may be needed if new t is minimal */
			else if (dir > 0)
				t -= ((time_t) 1) << bits;
			else	t += ((time_t) 1) << bits;
			continue;
		}
		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
			break;
		/*
		** Right time, wrong type.
		** Hunt for right time, right type.
		** It's okay to guess wrong since the guess
		** gets checked.
		*/
		/*
		** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
		*/
		sp = (const struct state *)
			(((void *) funcp == (void *) localsub) ?
			lclptr : gmtptr);
#ifdef ALL_STATE
		if (sp == NULL)
			return WRONG;
#endif /* defined ALL_STATE */
		for (i = sp->typecnt - 1; i >= 0; --i) {
			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
				continue;
			for (j = sp->typecnt - 1; j >= 0; --j) {
				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
					continue;
				newt = t + sp->ttis[j].tt_gmtoff -
					sp->ttis[i].tt_gmtoff;
				(*funcp)(&newt, offset, &mytm);
				if (tmcomp(&mytm, &yourtm) != 0)
					continue;
				if (mytm.tm_isdst != yourtm.tm_isdst)
					continue;
				/*
				** We have a match.
				*/
				t = newt;
				goto label;
			}
		}
		return WRONG;
	}
label:
	newt = t + saved_seconds;
	if ((newt < t) != (saved_seconds < 0))
		return WRONG;
	t = newt;
	(*funcp)(&t, offset, tmp);
	*okayp = TRUE;
	return t;
}

static time_t
time2(struct tm *tmp, void (*funcp) P((const time_t*, long, struct tm*)),
      const long offset, int *okayp)
{
	time_t	t;

	/*
	** First try without normalization of seconds
	** (in case tm_sec contains a value associated with a leap second).
	** If that fails, try with normalization of seconds.
	*/
	t = time2sub(tmp, funcp, offset, okayp, FALSE);
	return *okayp ? t : time2sub(tmp, funcp, offset, okayp, TRUE);
}

static time_t
time1(struct tm *tmp, void (*funcp) P((const time_t *, long, struct tm *)),
      const long offset)
{
	register time_t			t;
	register const struct state *	sp;
	register int			samei, otheri;
	int				okay;

	if (tmp->tm_isdst > 1)
		tmp->tm_isdst = 1;
	t = time2(tmp, funcp, offset, &okay);
#ifdef PCTS
	/*
	** PCTS code courtesy Grant Sullivan ([e-mail]).
	*/
	if (okay)
		return t;
	if (tmp->tm_isdst < 0)
		tmp->tm_isdst = 0;	/* reset to std and try again */
#endif /* defined PCTS */
#ifndef PCTS
	if (okay || tmp->tm_isdst < 0)
		return t;
#endif /* !defined PCTS */
	/*
	** We're supposed to assume that somebody took a time of one type
	** and did some math on it that yielded a "struct tm" that's bad.
	** We try to divine the type they started from and adjust to the
	** type they need.
	*/
	/*
	** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
	*/
	sp = (const struct state *) (((void *) funcp == (void *) localsub) ?
		lclptr : gmtptr);
#ifdef ALL_STATE
	if (sp == NULL)
		return WRONG;
#endif /* defined ALL_STATE */
	for (samei = sp->typecnt - 1; samei >= 0; --samei) {
		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
			continue;
		for (otheri = sp->typecnt - 1; otheri >= 0; --otheri) {
			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
				continue;
			tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
					sp->ttis[samei].tt_gmtoff;
			tmp->tm_isdst = !tmp->tm_isdst;
			t = time2(tmp, funcp, offset, &okay);
			if (okay)
				return t;
			tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
					sp->ttis[samei].tt_gmtoff;
			tmp->tm_isdst = !tmp->tm_isdst;
		}
	}
	return WRONG;
}

extern "C" time_t
mktime(struct tm *tmp)
{
	tzset();
	return time1(tmp, localsub, 0L);
}

#ifdef STD_INSPIRED

extern "C" time_t
timelocal(struct tm *tmp)
{
	tmp->tm_isdst = -1;	/* in case it wasn't initialized */
	return mktime(tmp);
}

extern "C" time_t
timegm(struct tm *tmp)
{
	tmp->tm_isdst = 0;
	return time1(tmp, gmtsub, 0L);
}

extern "C" time_t
timeoff(struct tm *tmp, const long offset)
{
	tmp->tm_isdst = 0;
	return time1(tmp, gmtsub, offset);
}

#endif /* defined STD_INSPIRED */

#ifdef CMUCS

/*
** The following is supplied for compatibility with
** previous versions of the CMUCS runtime library.
*/

extern "C" long
gtime(struct tm *tmp)
{
	const time_t	t = mktime(tmp);

	if (t == WRONG)
		return -1;
	return t;
}

#endif /* defined CMUCS */

/*
** XXX--is the below the right way to conditionalize??
*/

#ifdef STD_INSPIRED

/*
** IEEE Std 1003.1-1988 (POSIX) legislates that 536457599
** shall correspond to "Wed Dec 31 23:59:59 UTC 1986", which
** is not the case if we are accounting for leap seconds.
** So, we provide the following conversion routines for use
** when exchanging timestamps with POSIX conforming systems.
*/

static long
leapcorr(time_t *timep)
{
	register struct state *		sp;
	register struct lsinfo *	lp;
	register int			i;

	sp = lclptr;
	i = sp->leapcnt;
	while (--i >= 0) {
		lp = &sp->lsis[i];
		if (*timep >= lp->ls_trans)
			return lp->ls_corr;
	}
	return 0;
}

extern "C" time_t
time2posix(time_t t)
{
	tzset();
	return t - leapcorr(&t);
}

extern "C" time_t
posix2time(time_t t)
{
	time_t	x;
	time_t	y;

	tzset();
	/*
	** For a positive leap second hit, the result
	** is not unique.  For a negative leap second
	** hit, the corresponding time doesn't exist,
	** so we return an adjacent second.
	*/
	x = t + leapcorr(&t);
	y = x - leapcorr(&x);
	if (y < t) {
		do {
			x++;
			y = x - leapcorr(&x);
		} while (y < t);
		if (t != y)
			return x - 1;
	} else if (y > t) {
		do {
			--x;
			y = x - leapcorr(&x);
		} while (y > t);
		if (t != y)
			return x + 1;
	}
	return x;
}

#endif /* defined STD_INSPIRED */