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/*
* tzcalc_limits.c
* Original Author: Adapted from tzcode maintained by Arthur David Olson.
* Modifications:
* - Changed to mktm_r and added __tzcalc_limits - 04/10/02, Jeff Johnston
* - Fixed bug in mday computations - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
* - Fixed bug in __tzcalc_limits - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
* - Moved __tzcalc_limits() to separate file - 05/09/14, Freddie Chopin <freddie_chopin@op.pl>
*/
#include "local.h"
int
_DEFUN (__tzcalc_limits, (year),
int year)
{
int days, year_days, years;
int i, j;
__tzinfo_type *_CONST tz = __gettzinfo ();
if (year < EPOCH_YEAR)
return 0;
tz->__tzyear = year;
years = (year - EPOCH_YEAR);
year_days = years * 365 +
(years - 1 + EPOCH_YEARS_SINCE_LEAP) / 4 -
(years - 1 + EPOCH_YEARS_SINCE_CENTURY) / 100 +
(years - 1 + EPOCH_YEARS_SINCE_LEAP_CENTURY) / 400;
for (i = 0; i < 2; ++i)
{
if (tz->__tzrule[i].ch == 'J')
{
/* The Julian day n (1 <= n <= 365). */
days = year_days + tz->__tzrule[i].d +
(isleap(year) && tz->__tzrule[i].d >= 60);
/* Convert to yday */
--days;
}
else if (tz->__tzrule[i].ch == 'D')
days = year_days + tz->__tzrule[i].d;
else
{
_CONST int yleap = isleap(year);
int m_day, m_wday, wday_diff;
_CONST int *_CONST ip = __month_lengths[yleap];
days = year_days;
for (j = 1; j < tz->__tzrule[i].m; ++j)
days += ip[j-1];
m_wday = (EPOCH_WDAY + days) % DAYSPERWEEK;
wday_diff = tz->__tzrule[i].d - m_wday;
if (wday_diff < 0)
wday_diff += DAYSPERWEEK;
m_day = (tz->__tzrule[i].n - 1) * DAYSPERWEEK + wday_diff;
while (m_day >= ip[j-1])
m_day -= DAYSPERWEEK;
days += m_day;
}
/* store the change-over time in GMT form by adding offset */
tz->__tzrule[i].change = days * SECSPERDAY +
tz->__tzrule[i].s + tz->__tzrule[i].offset;
}
tz->__tznorth = (tz->__tzrule[0].change < tz->__tzrule[1].change);
return 1;
}
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