Initial revision

rtc/date.c

+/*
+ * (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 (CONFIG_COMMANDS & CFG_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	/* CFG_CMD_DATE */