/* Copyright (C) 1991, 1993, 1997, 1998 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include <time.h> #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. Return nonzero if successful. */ int __offtime (t, offset, tp) const time_t *t; long int offset; struct tm *tp; { long int days, rem, y; 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 DIV(a, b) ((a) / (b) - ((a) % (b) < 0)) #define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400)) while (days < 0 || days >= (__isleap (y) ? 366 : 365)) { /* Guess a corrected year, assuming 365 days per year. */ long 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; if (tp->tm_year != y - 1900) return 0; tp->tm_yday = days; ip = __mon_yday[__isleap(y)]; for (y = 11; days < (long int) ip[y]; --y) continue; days -= ip[y]; tp->tm_mon = y; tp->tm_mday = days + 1; return 1; }