LXR uboot/drivers/rtc/date.c

   1/*
   2 * (C) Copyright 2001
   3 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4 *
   5 * See file CREDITS for list of people who contributed to this
   6 * project.
   7 *
   8 * This program is free software; you can redistribute it and/or
   9 * modify it under the terms of the GNU General Public License as
  10 * published by the Free Software Foundation; either version 2 of
  11 * the License, or (at your option) any later version.
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21 * MA 02111-1307 USA
  22 */
  23
  24/*
  25 * Date & Time support for Philips PCF8563 RTC
  26 */
  27
  28#include <common.h>
  29#include <command.h>
  30#include <rtc.h>
  31
  32#if defined(CONFIG_CMD_DATE) || defined(CONFIG_TIMESTAMP)
  33
  34#define FEBRUARY                2
  35#define STARTOFTIME             1970
  36#define SECDAY                  86400L
  37#define SECYR                   (SECDAY * 365)
  38#define leapyear(year)          ((year) % 4 == 0)
  39#define days_in_year(a)         (leapyear(a) ? 366 : 365)
  40#define days_in_month(a)        (month_days[(a) - 1])
  41
  42static int month_days[12] = {
  43        31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
  44};
  45
  46/*
  47 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
  48 */
  49void GregorianDay(struct rtc_time * tm)
  50{
  51        int leapsToDate;
  52        int lastYear;
  53        int day;
  54        int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 };
  55
  56        lastYear=tm->tm_year-1;
  57
  58        /*
  59         * Number of leap corrections to apply up to end of last year
  60         */
  61        leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;
  62
  63        /*
  64         * This year is a leap year if it is divisible by 4 except when it is
  65         * divisible by 100 unless it is divisible by 400
  66         *
  67         * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be
  68         */
  69        if((tm->tm_year%4==0) &&
  70           ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
  71           (tm->tm_mon>2)) {
  72                /*
  73                 * We are past Feb. 29 in a leap year
  74                 */
  75                day=1;
  76        } else {
  77                day=0;
  78        }
  79
  80        day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday;
  81
  82        tm->tm_wday=day%7;
  83}
  84
  85void to_tm(int tim, struct rtc_time * tm)
  86{
  87        register int    i;
  88        register long   hms, day;
  89
  90        day = tim / SECDAY;
  91        hms = tim % SECDAY;
  92
  93        /* Hours, minutes, seconds are easy */
  94        tm->tm_hour = hms / 3600;
  95        tm->tm_min = (hms % 3600) / 60;
  96        tm->tm_sec = (hms % 3600) % 60;
  97
  98        /* Number of years in days */
  99        for (i = STARTOFTIME; day >= days_in_year(i); i++) {
 100                day -= days_in_year(i);
 101        }
 102        tm->tm_year = i;
 103
 104        /* Number of months in days left */
 105        if (leapyear(tm->tm_year)) {
 106                days_in_month(FEBRUARY) = 29;
 107        }
 108        for (i = 1; day >= days_in_month(i); i++) {
 109                day -= days_in_month(i);
 110        }
 111        days_in_month(FEBRUARY) = 28;
 112        tm->tm_mon = i;
 113
 114        /* Days are what is left over (+1) from all that. */
 115        tm->tm_mday = day + 1;
 116
 117        /*
 118         * Determine the day of week
 119         */
 120        GregorianDay(tm);
 121}
 122
 123/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
 124 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
 125 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
 126 *
 127 * [For the Julian calendar (which was used in Russia before 1917,
 128 * Britain & colonies before 1752, anywhere else before 1582,
 129 * and is still in use by some communities) leave out the
 130 * -year/100+year/400 terms, and add 10.]
 131 *
 132 * This algorithm was first published by Gauss (I think).
 133 *
 134 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
 135 * machines were long is 32-bit! (However, as time_t is signed, we
 136 * will already get problems at other places on 2038-01-19 03:14:08)
 137 */
 138unsigned long
 139mktime (unsigned int year, unsigned int mon,
 140        unsigned int day, unsigned int hour,
 141        unsigned int min, unsigned int sec)
 142{
 143        if (0 >= (int) (mon -= 2)) {    /* 1..12 -> 11,12,1..10 */
 144                mon += 12;              /* Puts Feb last since it has leap day */
 145                year -= 1;
 146        }
 147
 148        return (((
 149                (unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) +
 150                        year*365 - 719499
 151            )*24 + hour /* now have hours */
 152          )*60 + min /* now have minutes */
 153        )*60 + sec; /* finally seconds */
 154}
 155
 156#endif
 157