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Diffstat (limited to 'drivers/rtc/date.c')
| -rw-r--r-- | drivers/rtc/date.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/drivers/rtc/date.c b/drivers/rtc/date.c new file mode 100644 index 0000000..a83a723 --- /dev/null +++ b/drivers/rtc/date.c @@ -0,0 +1,156 @@ +/* + * (C) Copyright 2001 + * Wolfgang Denk, DENX Software Engineering, wd@denx.de. + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +/* + * Date & Time support for Philips PCF8563 RTC + */ + +#include <common.h> +#include <command.h> +#include <rtc.h> + +#if defined(CONFIG_CMD_DATE) || defined(CONFIG_TIMESTAMP) + +#define FEBRUARY 2 +#define STARTOFTIME 1970 +#define SECDAY 86400L +#define SECYR (SECDAY * 365) +#define leapyear(year) ((year) % 4 == 0) +#define days_in_year(a) (leapyear(a) ? 366 : 365) +#define days_in_month(a) (month_days[(a) - 1]) + +static int month_days[12] = { + 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 +}; + +/* + * This only works for the Gregorian calendar - i.e. after 1752 (in the UK) + */ +void GregorianDay(struct rtc_time * tm) +{ + int leapsToDate; + int lastYear; + int day; + int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 }; + + lastYear=tm->tm_year-1; + + /* + * Number of leap corrections to apply up to end of last year + */ + leapsToDate = lastYear/4 - lastYear/100 + lastYear/400; + + /* + * This year is a leap year if it is divisible by 4 except when it is + * divisible by 100 unless it is divisible by 400 + * + * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be + */ + if((tm->tm_year%4==0) && + ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) && + (tm->tm_mon>2)) { + /* + * We are past Feb. 29 in a leap year + */ + day=1; + } else { + day=0; + } + + day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday; + + tm->tm_wday=day%7; +} + +void to_tm(int tim, struct rtc_time * tm) +{ + register int i; + register long hms, day; + + day = tim / SECDAY; + hms = tim % SECDAY; + + /* Hours, minutes, seconds are easy */ + tm->tm_hour = hms / 3600; + tm->tm_min = (hms % 3600) / 60; + tm->tm_sec = (hms % 3600) % 60; + + /* Number of years in days */ + for (i = STARTOFTIME; day >= days_in_year(i); i++) { + day -= days_in_year(i); + } + tm->tm_year = i; + + /* Number of months in days left */ + if (leapyear(tm->tm_year)) { + days_in_month(FEBRUARY) = 29; + } + for (i = 1; day >= days_in_month(i); i++) { + day -= days_in_month(i); + } + days_in_month(FEBRUARY) = 28; + tm->tm_mon = i; + + /* Days are what is left over (+1) from all that. */ + tm->tm_mday = day + 1; + + /* + * Determine the day of week + */ + GregorianDay(tm); +} + +/* 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). + * + * WARNING: this function will overflow on 2106-02-07 06:28:16 on + * machines were long is 32-bit! (However, as time_t is signed, we + * will already get problems at other places on 2038-01-19 03:14:08) + */ +unsigned long +mktime (unsigned int year, unsigned int mon, + unsigned int day, unsigned int hour, + unsigned int min, unsigned int sec) +{ + if (0 >= (int) (mon -= 2)) { /* 1..12 -> 11,12,1..10 */ + mon += 12; /* Puts Feb last since it has leap day */ + year -= 1; + } + + return ((( + (unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) + + year*365 - 719499 + )*24 + hour /* now have hours */ + )*60 + min /* now have minutes */ + )*60 + sec; /* finally seconds */ +} + +#endif |