mirror of
https://gitlab.com/sortix/sortix.git
synced 2023-02-13 20:55:38 -05:00
296 lines
7.4 KiB
C++
296 lines
7.4 KiB
C++
/*******************************************************************************
|
|
|
|
Copyright(C) Jonas 'Sortie' Termansen 2013.
|
|
|
|
This file is part of the Sortix C Library.
|
|
|
|
The Sortix C Library is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or (at your
|
|
option) any later version.
|
|
|
|
The Sortix 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 Lesser General Public
|
|
License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
time/gmtime_r.cpp
|
|
Convert a timestamp into a date and time according to UTC.
|
|
|
|
*******************************************************************************/
|
|
|
|
#include <time.h>
|
|
|
|
#include <stdint.h>
|
|
#include <time.h>
|
|
|
|
static const int DAYS_JANUARY = 31;
|
|
static const int DAYS_FEBRUARY = 28;
|
|
static const int DAYS_MARCH = 31;
|
|
static const int DAYS_APRIL = 30;
|
|
static const int DAYS_MAY = 31;
|
|
static const int DAYS_JUNE = 30;
|
|
static const int DAYS_JULY = 31;
|
|
static const int DAYS_AUGUST = 31;
|
|
static const int DAYS_SEPTEMBER = 30;
|
|
static const int DAYS_OCTOBER = 31;
|
|
static const int DAYS_NOVEMBER = 30;
|
|
static const int DAYS_DECEMBER = 31;
|
|
|
|
#define DECL_LEAP_SECOND(year, jun, dec) \
|
|
{0, 0, 0, 0, 0, jun, 0, 0, 0, 0, 0, dec}
|
|
|
|
static int8_t leap_seconds[][12] =
|
|
{
|
|
DECL_LEAP_SECOND(1970, 0, 0),
|
|
DECL_LEAP_SECOND(1971, 0, 0),
|
|
DECL_LEAP_SECOND(1972, 0, 0),
|
|
DECL_LEAP_SECOND(1972, 1, 1),
|
|
DECL_LEAP_SECOND(1973, 0, 1),
|
|
DECL_LEAP_SECOND(1974, 0, 1),
|
|
DECL_LEAP_SECOND(1975, 0, 1),
|
|
DECL_LEAP_SECOND(1976, 0, 1),
|
|
DECL_LEAP_SECOND(1977, 0, 1),
|
|
DECL_LEAP_SECOND(1978, 0, 1),
|
|
DECL_LEAP_SECOND(1979, 0, 1),
|
|
DECL_LEAP_SECOND(1980, 0, 0),
|
|
DECL_LEAP_SECOND(1981, 1, 0),
|
|
DECL_LEAP_SECOND(1982, 1, 0),
|
|
DECL_LEAP_SECOND(1983, 1, 0),
|
|
DECL_LEAP_SECOND(1984, 0, 0),
|
|
DECL_LEAP_SECOND(1985, 1, 0),
|
|
DECL_LEAP_SECOND(1986, 0, 0),
|
|
DECL_LEAP_SECOND(1987, 0, 1),
|
|
DECL_LEAP_SECOND(1988, 0, 0),
|
|
DECL_LEAP_SECOND(1989, 0, 1),
|
|
DECL_LEAP_SECOND(1990, 0, 1),
|
|
DECL_LEAP_SECOND(1991, 0, 0),
|
|
DECL_LEAP_SECOND(1992, 1, 0),
|
|
DECL_LEAP_SECOND(1993, 1, 0),
|
|
DECL_LEAP_SECOND(1994, 1, 0),
|
|
DECL_LEAP_SECOND(1995, 0, 1),
|
|
DECL_LEAP_SECOND(1996, 0, 0),
|
|
DECL_LEAP_SECOND(1997, 1, 0),
|
|
DECL_LEAP_SECOND(1998, 0, 1),
|
|
DECL_LEAP_SECOND(1999, 0, 0),
|
|
DECL_LEAP_SECOND(2000, 0, 0),
|
|
DECL_LEAP_SECOND(2001, 0, 0),
|
|
DECL_LEAP_SECOND(2002, 0, 0),
|
|
DECL_LEAP_SECOND(2003, 0, 0),
|
|
DECL_LEAP_SECOND(2004, 0, 0),
|
|
DECL_LEAP_SECOND(2005, 0, 1),
|
|
DECL_LEAP_SECOND(2006, 0, 0),
|
|
DECL_LEAP_SECOND(2007, 0, 0),
|
|
DECL_LEAP_SECOND(2008, 0, 1),
|
|
DECL_LEAP_SECOND(2009, 0, 0),
|
|
DECL_LEAP_SECOND(2010, 0, 0),
|
|
DECL_LEAP_SECOND(2011, 0, 0),
|
|
DECL_LEAP_SECOND(2012, 1, 0),
|
|
DECL_LEAP_SECOND(2013, 0, 0),
|
|
DECL_LEAP_SECOND(2014, 0, 0),
|
|
DECL_LEAP_SECOND(2015, 1, 0),
|
|
};
|
|
|
|
static time_t get_leap_second(int year, int month)
|
|
{
|
|
const time_t num_years = sizeof(leap_seconds) / sizeof(leap_seconds[0]);
|
|
if ( year < 1970 )
|
|
return 0;
|
|
if ( num_years <= year-1970 )
|
|
return 0;
|
|
return leap_seconds[year-1970][month];
|
|
}
|
|
|
|
static time_t leap_seconds_in_year(int year)
|
|
{
|
|
time_t ret = 0;
|
|
for ( int i = 0; i < 12; i++ )
|
|
ret += get_leap_second(year, i);
|
|
return ret;
|
|
}
|
|
|
|
static bool is_leap_year(int year)
|
|
{
|
|
return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
|
|
}
|
|
|
|
static time_t days_in_year(int year)
|
|
{
|
|
return DAYS_JANUARY +
|
|
DAYS_FEBRUARY + (is_leap_year(year) ? 1 : 0) +
|
|
DAYS_MARCH +
|
|
DAYS_APRIL +
|
|
DAYS_MAY +
|
|
DAYS_JUNE +
|
|
DAYS_JULY +
|
|
DAYS_AUGUST +
|
|
DAYS_SEPTEMBER +
|
|
DAYS_OCTOBER +
|
|
DAYS_NOVEMBER +
|
|
DAYS_DECEMBER;
|
|
}
|
|
|
|
extern "C" struct tm* gmtime_r(const time_t* time_ptr, struct tm* ret)
|
|
{
|
|
time_t left = *time_ptr;
|
|
|
|
ret->tm_year = 1970;
|
|
ret->tm_wday = 4 /* Supposedly, the world began on a Thursday. */;
|
|
|
|
// If the timestamp is after the epoch.
|
|
while ( 0 < left )
|
|
{
|
|
time_t year_leaps = leap_seconds_in_year(ret->tm_year);
|
|
time_t year_days = days_in_year(ret->tm_year);
|
|
time_t year_seconds = year_days * 24 * 60 * 60 + year_leaps;
|
|
if ( year_seconds <= left )
|
|
{
|
|
left -= year_seconds;
|
|
ret->tm_wday = (ret->tm_wday + year_days) % 7;
|
|
ret->tm_year++;
|
|
continue;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// If the timestamp was before the epoch.
|
|
while ( left < 0 )
|
|
{
|
|
ret->tm_year--;
|
|
time_t year_leaps = leap_seconds_in_year(ret->tm_year);
|
|
time_t year_days = days_in_year(ret->tm_year);
|
|
time_t year_seconds = year_days * 24 * 60 * 60 + year_leaps;
|
|
left += year_seconds;
|
|
// We need to avoid taking the modulo of a negative value or the
|
|
// (broken) C modulo operator gives the wrong result.
|
|
ret->tm_wday = (ret->tm_wday - year_days + 7*7*7*7) % 7;
|
|
}
|
|
|
|
int month_days_list[12] =
|
|
{
|
|
DAYS_JANUARY,
|
|
DAYS_FEBRUARY + (is_leap_year(ret->tm_year) ? 1 : 0),
|
|
DAYS_MARCH,
|
|
DAYS_APRIL,
|
|
DAYS_MAY,
|
|
DAYS_JUNE,
|
|
DAYS_JULY,
|
|
DAYS_AUGUST,
|
|
DAYS_SEPTEMBER,
|
|
DAYS_OCTOBER,
|
|
DAYS_NOVEMBER,
|
|
DAYS_DECEMBER,
|
|
};
|
|
|
|
// Figure out the correct month.
|
|
ret->tm_mon = 0;
|
|
ret->tm_yday = 0;
|
|
while ( true )
|
|
{
|
|
int month_leaps = get_leap_second(ret->tm_year, ret->tm_mon);
|
|
int month_days = month_days_list[ret->tm_mon];
|
|
int month_seconds = month_days * 24 * 60 * 60 + month_leaps;
|
|
if ( month_seconds <= left )
|
|
{
|
|
left -= month_seconds;
|
|
ret->tm_mon++;
|
|
ret->tm_yday += month_days;
|
|
ret->tm_wday = (ret->tm_wday + month_days) % 7;
|
|
continue;
|
|
}
|
|
break;
|
|
}
|
|
|
|
ret->tm_mday = left / (24 * 60 * 60);
|
|
left = left % (24 * 60 * 60);
|
|
|
|
// If this is a regular timestamp.
|
|
if ( ret->tm_mday < month_days_list[ret->tm_mon] )
|
|
{
|
|
ret->tm_yday += ret->tm_mday;
|
|
|
|
ret->tm_hour = left / (60 * 60);
|
|
left = left % (60 * 60);
|
|
|
|
ret->tm_min = left / 60;
|
|
left = left % 60;
|
|
|
|
ret->tm_sec = left;
|
|
}
|
|
|
|
// If we got the timestamp for an added leap second.
|
|
else
|
|
{
|
|
ret->tm_mday--; // Seemingly additional day.
|
|
ret->tm_yday += ret->tm_mday;
|
|
ret->tm_hour = 23;
|
|
ret->tm_min = 59;
|
|
ret->tm_sec = 60;
|
|
}
|
|
|
|
ret->tm_wday = (ret->tm_wday + ret->tm_mday) % 7;
|
|
|
|
// TODO: Support daylight savings and timezones.
|
|
ret->tm_isdst = -1;
|
|
|
|
// Fix the ranges of some of the variables.
|
|
ret->tm_mday += 1;
|
|
ret->tm_year -= 1900;
|
|
|
|
return ret;
|
|
}
|
|
|
|
extern "C" time_t timegm(struct tm* tm)
|
|
{
|
|
time_t year = tm->tm_year + 1900;
|
|
time_t month = tm->tm_mon;
|
|
time_t day = tm->tm_mday - 1;
|
|
time_t hour = tm->tm_hour;
|
|
time_t minute = tm->tm_min;
|
|
time_t second = tm->tm_sec;
|
|
|
|
time_t ret = 0;
|
|
for ( time_t y = 1970; y < year; y++ )
|
|
{
|
|
time_t year_leaps = leap_seconds_in_year(y);
|
|
time_t year_days = days_in_year(y);
|
|
time_t year_seconds = year_days * 24 * 60 * 60 + year_leaps;
|
|
ret += year_seconds;
|
|
}
|
|
|
|
int month_days_list[12] =
|
|
{
|
|
DAYS_JANUARY,
|
|
DAYS_FEBRUARY + (is_leap_year(year) ? 1 : 0),
|
|
DAYS_MARCH,
|
|
DAYS_APRIL,
|
|
DAYS_MAY,
|
|
DAYS_JUNE,
|
|
DAYS_JULY,
|
|
DAYS_AUGUST,
|
|
DAYS_SEPTEMBER,
|
|
DAYS_OCTOBER,
|
|
DAYS_NOVEMBER,
|
|
DAYS_DECEMBER,
|
|
};
|
|
|
|
for ( uint8_t m = 0; m < month; m++ )
|
|
{
|
|
int month_leaps = get_leap_second(year, m);
|
|
int month_days = month_days_list[m];
|
|
int month_seconds = month_days * 24 * 60 * 60 + month_leaps;
|
|
ret += month_seconds;
|
|
}
|
|
|
|
ret += (time_t) day * 24 * 60 * 60;
|
|
ret += (time_t) hour * 60 * 60;
|
|
ret += (time_t) minute * 60;
|
|
ret += (time_t) second * 1;
|
|
|
|
gmtime_r(&ret, tm);
|
|
|
|
return ret;
|
|
}
|