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rtc/date.c
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156
rtc/date.c
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/*
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* (C) Copyright 2001
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* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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/*
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* Date & Time support for Philips PCF8563 RTC
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*/
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#include <common.h>
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#include <command.h>
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#include <rtc.h>
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#if (CONFIG_COMMANDS & CFG_CMD_DATE) || defined(CONFIG_TIMESTAMP)
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#define FEBRUARY 2
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#define STARTOFTIME 1970
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#define SECDAY 86400L
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#define SECYR (SECDAY * 365)
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#define leapyear(year) ((year) % 4 == 0)
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#define days_in_year(a) (leapyear(a) ? 366 : 365)
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#define days_in_month(a) (month_days[(a) - 1])
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static int month_days[12] = {
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31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
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};
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/*
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* This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
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*/
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void GregorianDay(struct rtc_time * tm)
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{
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int leapsToDate;
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int lastYear;
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int day;
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int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 };
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lastYear=tm->tm_year-1;
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/*
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* Number of leap corrections to apply up to end of last year
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*/
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leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;
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/*
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* This year is a leap year if it is divisible by 4 except when it is
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* divisible by 100 unless it is divisible by 400
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*
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* e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be
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*/
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if((tm->tm_year%4==0) &&
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((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
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(tm->tm_mon>2)) {
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/*
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* We are past Feb. 29 in a leap year
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*/
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day=1;
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} else {
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day=0;
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}
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day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday;
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tm->tm_wday=day%7;
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}
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void to_tm(int tim, struct rtc_time * tm)
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{
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register int i;
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register long hms, day;
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day = tim / SECDAY;
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hms = tim % SECDAY;
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/* Hours, minutes, seconds are easy */
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tm->tm_hour = hms / 3600;
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tm->tm_min = (hms % 3600) / 60;
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tm->tm_sec = (hms % 3600) % 60;
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/* Number of years in days */
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for (i = STARTOFTIME; day >= days_in_year(i); i++) {
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day -= days_in_year(i);
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}
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tm->tm_year = i;
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/* Number of months in days left */
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if (leapyear(tm->tm_year)) {
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days_in_month(FEBRUARY) = 29;
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}
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for (i = 1; day >= days_in_month(i); i++) {
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day -= days_in_month(i);
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}
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days_in_month(FEBRUARY) = 28;
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tm->tm_mon = i;
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/* Days are what is left over (+1) from all that. */
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tm->tm_mday = day + 1;
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/*
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* Determine the day of week
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*/
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GregorianDay(tm);
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}
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/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
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* Assumes input in normal date format, i.e. 1980-12-31 23:59:59
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* => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
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*
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* [For the Julian calendar (which was used in Russia before 1917,
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* Britain & colonies before 1752, anywhere else before 1582,
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* and is still in use by some communities) leave out the
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* -year/100+year/400 terms, and add 10.]
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*
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* This algorithm was first published by Gauss (I think).
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*
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* WARNING: this function will overflow on 2106-02-07 06:28:16 on
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* machines were long is 32-bit! (However, as time_t is signed, we
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* will already get problems at other places on 2038-01-19 03:14:08)
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*/
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unsigned long
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mktime (unsigned int year, unsigned int mon,
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unsigned int day, unsigned int hour,
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unsigned int min, unsigned int sec)
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{
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if (0 >= (int) (mon -= 2)) { /* 1..12 -> 11,12,1..10 */
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mon += 12; /* Puts Feb last since it has leap day */
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year -= 1;
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}
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return (((
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(unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) +
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year*365 - 719499
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)*24 + hour /* now have hours */
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)*60 + min /* now have minutes */
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)*60 + sec; /* finally seconds */
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}
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#endif /* CFG_CMD_DATE */
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