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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_lengths[2][12];
#define SECS_PER_HOUR (60 * 60)
#define SECS_PER_DAY (SECS_PER_HOUR * 24)
/* Returns the `struct tm' representation of *T,
offset OFFSET seconds east of UCT. */
struct tm *
DEFUN(__offtime, (t, offset), CONST time_t *t AND long int offset)
{
static struct tm tbuf;
register long int days, rem;
register int y;
register CONST unsigned short int *ip;
if (t == NULL)
return NULL;
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;
}
tbuf.tm_hour = rem / SECS_PER_HOUR;
rem %= SECS_PER_HOUR;
tbuf.tm_min = rem / 60;
tbuf.tm_sec = rem % 60;
/* January 1, 1970 was a Thursday. */
tbuf.tm_wday = (4 + days) % 7;
if (tbuf.tm_wday < 0)
tbuf.tm_wday += 7;
y = 1970;
while (days >= (rem = __isleap(y) ? 366 : 365))
{
++y;
days -= rem;
}
while (days < 0)
{
--y;
days += __isleap(y) ? 366 : 365;
}
tbuf.tm_year = y - 1900;
tbuf.tm_yday = days;
ip = __mon_lengths[__isleap(y)];
for (y = 0; days >= ip[y]; ++y)
days -= ip[y];
tbuf.tm_mon = y;
tbuf.tm_mday = days + 1;
tbuf.tm_isdst = -1;
return &tbuf;
}
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