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/*
* rtc and date/time utility functions
*
* Copyright (C) 2005-06 Tower Technologies
* Author: Alessandro Zummo <[email protected]>
*
* based on arch/arm/common/rtctime.c and other bits
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <rtc/rtc.h>
static const unsigned char rtc_days_in_month[] =
{
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
static const unsigned short rtc_ydays[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 LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
/*
* The number of days in the month.
*/
int rtc_month_days(unsigned int month, unsigned int year)
{
return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
}
/*
* The number of days since January 1. (0 to 365)
*/
int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
{
return rtc_ydays[is_leap_year(year)][month] + day - 1;
}
/*
* Does the rtc_time represent a valid date/time?
*/
int rtc_valid_tm(struct rtc_time *tm)
{
if (tm->tm_year < 70
|| ((unsigned)tm->tm_mon) >= 12
|| tm->tm_mday < 1
|| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
|| ((unsigned)tm->tm_hour) >= 24
|| ((unsigned)tm->tm_min) >= 60
|| ((unsigned)tm->tm_sec) >= 60)
{
return -1;
}
return 0;
}
/*
* mktime64 - Converts date to seconds.
* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
* Assumes input in normal date format, i.e. 1980-12-31 23:59:59
* => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
*
* [For the Julian calendar (which was used in Russia before 1917,
* Britain & colonies before 1752, anywhere else before 1582,
* and is still in use by some communities) leave out the
* -year/100+year/400 terms, and add 10.]
*
* This algorithm was first published by Gauss (I think).
*
* A leap second can be indicated by calling this function with sec as
* 60 (allowable under ISO 8601). The leap second is treated the same
* as the following second since they don't exist in UNIX time.
*
* An encoding of midnight at the end of the day as 24:00:00 - ie. midnight
* tomorrow - (allowable under ISO 8601) is supported.
*/
time64_t mktime64(const unsigned int year0, const unsigned int mon0,
const unsigned int day, const unsigned int hour,
const unsigned int min, const unsigned int sec)
{
unsigned int mon = mon0, year = year0;
time64_t diff;
/* 1..12 -> 11,12,1..10 */
if (0 >= (int)(mon -= 2))
{
mon += 12; /* Puts Feb last since it has leap day */
year -= 1;
}
return ((((time64_t)
(year / 4 - year / 100 + year / 400 + 367 * mon / 12 + day) +
year * 365 - 719499
) * 24 + hour /* now have hours - midnight tomorrow handled here */
) * 60 + min /* now have minutes */
) * 60 + sec; /* finally seconds */
}
/*
* rtc_tm_to_time64 - Converts rtc_time to time64_t.
* Convert Gregorian date to seconds since 01-01-1970 00:00:00.
*/
time64_t rtc_tm_to_time64(struct rtc_time *tm)
{
return mktime64(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
}
static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
{
*remainder = dividend % divisor;
return dividend / divisor;
}
static s64 div_s64_rem(s64 dividend, s32 divisor, unsigned int *remainder)
{
u64 quotient;
if (dividend < 0)
{
quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
*remainder = -*remainder;
if (divisor > 0)
{
quotient = -quotient;
}
}
else
{
quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
if (divisor < 0)
{
quotient = -quotient;
}
}
return quotient;
}
/*
* rtc_time_to_tm64 - Converts time64_t to rtc_time.
* Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
*/
void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
{
unsigned int month, year, secs;
int days;
/* time must be positive */
days = div_s64_rem(time, 86400, &secs);
/* day of the week, 1970-01-01 was a Thursday */
tm->tm_wday = (days + 4) % 7;
year = 1970 + days / 365;
days -= (year - 1970) * 365
+ LEAPS_THRU_END_OF(year - 1)
- LEAPS_THRU_END_OF(1970 - 1);
if (days < 0)
{
year -= 1;
days += 365 + is_leap_year(year);
}
tm->tm_year = year - 1900;
tm->tm_yday = days + 1;
for (month = 0; month < 11; month++)
{
int newdays;
newdays = days - rtc_month_days(month, year);
if (newdays < 0)
{
break;
}
days = newdays;
}
tm->tm_mon = month;
tm->tm_mday = days + 1;
tm->tm_hour = secs / 3600;
secs -= tm->tm_hour * 3600;
tm->tm_min = secs / 60;
tm->tm_sec = secs - tm->tm_min * 60;
tm->tm_isdst = 0;
}
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