130 lines
3.6 KiB
C
130 lines
3.6 KiB
C
// SPDX-License-Identifier: LGPL-2.0+
|
|
/*
|
|
* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
|
|
* This file is part of the GNU C Library.
|
|
* Contributed by Paul Eggert (eggert@twinsun.com).
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
/*
|
|
* Converts the calendar time to broken-down time representation
|
|
* Based on code from glibc-2.6
|
|
*
|
|
* 2009-7-14:
|
|
* Moved from glibc-2.6 to kernel by Zhaolei<zhaolei@cn.fujitsu.com>
|
|
*/
|
|
|
|
#include <linux/time.h>
|
|
#include <linux/module.h>
|
|
|
|
/*
|
|
* Nonzero if YEAR is a leap year (every 4 years,
|
|
* except every 100th isn't, and every 400th is).
|
|
*/
|
|
static int __isleap(long year)
|
|
{
|
|
return (year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0);
|
|
}
|
|
|
|
/* do a mathdiv for long type */
|
|
static long math_div(long a, long b)
|
|
{
|
|
return a / b - (a % b < 0);
|
|
}
|
|
|
|
/* How many leap years between y1 and y2, y1 must less or equal to y2 */
|
|
static long leaps_between(long y1, long y2)
|
|
{
|
|
long leaps1 = math_div(y1 - 1, 4) - math_div(y1 - 1, 100)
|
|
+ math_div(y1 - 1, 400);
|
|
long leaps2 = math_div(y2 - 1, 4) - math_div(y2 - 1, 100)
|
|
+ math_div(y2 - 1, 400);
|
|
return leaps2 - leaps1;
|
|
}
|
|
|
|
/* How many days come before each month (0-12). */
|
|
static const unsigned short __mon_yday[2][13] = {
|
|
/* Normal years. */
|
|
{0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
|
|
/* Leap years. */
|
|
{0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
|
|
};
|
|
|
|
#define SECS_PER_HOUR (60 * 60)
|
|
#define SECS_PER_DAY (SECS_PER_HOUR * 24)
|
|
|
|
/**
|
|
* time64_to_tm - converts the calendar time to local broken-down time
|
|
*
|
|
* @totalsecs: the number of seconds elapsed since 00:00:00 on January 1, 1970,
|
|
* Coordinated Universal Time (UTC).
|
|
* @offset: offset seconds adding to totalsecs.
|
|
* @result: pointer to struct tm variable to receive broken-down time
|
|
*/
|
|
void time64_to_tm(time64_t totalsecs, int offset, struct tm *result)
|
|
{
|
|
long days, rem, y;
|
|
int remainder;
|
|
const unsigned short *ip;
|
|
|
|
days = div_s64_rem(totalsecs, SECS_PER_DAY, &remainder);
|
|
rem = remainder;
|
|
rem += offset;
|
|
while (rem < 0) {
|
|
rem += SECS_PER_DAY;
|
|
--days;
|
|
}
|
|
while (rem >= SECS_PER_DAY) {
|
|
rem -= SECS_PER_DAY;
|
|
++days;
|
|
}
|
|
|
|
result->tm_hour = rem / SECS_PER_HOUR;
|
|
rem %= SECS_PER_HOUR;
|
|
result->tm_min = rem / 60;
|
|
result->tm_sec = rem % 60;
|
|
|
|
/* January 1, 1970 was a Thursday. */
|
|
result->tm_wday = (4 + days) % 7;
|
|
if (result->tm_wday < 0)
|
|
result->tm_wday += 7;
|
|
|
|
y = 1970;
|
|
|
|
while (days < 0 || days >= (__isleap(y) ? 366 : 365)) {
|
|
/* Guess a corrected year, assuming 365 days per year. */
|
|
long yg = y + math_div(days, 365);
|
|
|
|
/* Adjust DAYS and Y to match the guessed year. */
|
|
days -= (yg - y) * 365 + leaps_between(y, yg);
|
|
y = yg;
|
|
}
|
|
|
|
result->tm_year = y - 1900;
|
|
|
|
result->tm_yday = days;
|
|
|
|
ip = __mon_yday[__isleap(y)];
|
|
for (y = 11; days < ip[y]; y--)
|
|
continue;
|
|
days -= ip[y];
|
|
|
|
result->tm_mon = y;
|
|
result->tm_mday = days + 1;
|
|
}
|
|
EXPORT_SYMBOL(time64_to_tm);
|