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/* Copyright (C) 1991, 1993 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <time.h>
/* Defined in mktime.c. */
extern CONST unsigned short int __mon_yday[2][13];
#define SECS_PER_HOUR (60 * 60)
#define SECS_PER_DAY (SECS_PER_HOUR * 24)
/* Compute the `struct tm' representation of *T,
offset OFFSET seconds east of UTC,
and store year, yday, mon, mday, wday, hour, min, sec into *TP. */
void
DEFUN(__offtime, (t, offset, tp),
CONST time_t *t AND long int offset AND struct tm *tp)
{
register long int days, rem, y;
register CONST unsigned short int *ip;
days = *t / SECS_PER_DAY;
rem = *t % SECS_PER_DAY;
rem += offset;
while (rem < 0)
{
rem += SECS_PER_DAY;
--days;
}
while (rem >= SECS_PER_DAY)
{
rem -= SECS_PER_DAY;
++days;
}
tp->tm_hour = rem / SECS_PER_HOUR;
rem %= SECS_PER_HOUR;
tp->tm_min = rem / 60;
tp->tm_sec = rem % 60;
/* January 1, 1970 was a Thursday. */
tp->tm_wday = (4 + days) % 7;
if (tp->tm_wday < 0)
tp->tm_wday += 7;
y = 1970;
# define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
while (days < 0 || days >= (__isleap (y) ? 366 : 365))
{
/* Guess a corrected year, assuming 365 days per year. */
int yg = y + days / 365 - (days % 365 < 0);
/* Adjust DAYS and Y to match the guessed year. */
days -= ((yg - y) * 365
+ LEAPS_THRU_END_OF (yg - 1)
- LEAPS_THRU_END_OF (y - 1));
y = yg;
}
tp->tm_year = y - 1900;
tp->tm_yday = days;
ip = __mon_yday[__isleap(y)];
for (y = 11; days < ip[y]; --y)
continue;
days -= ip[y];
tp->tm_mon = y;
tp->tm_mday = days + 1;
}
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