LXR uboot/lib/date.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * (C) Copyright 2001
   4 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   5 */
   6
   7#include <common.h>
   8#include <command.h>
   9#include <errno.h>
  10#include <rtc.h>
  11#include <linux/time.h>
  12
  13#define FEBRUARY                2
  14#define STARTOFTIME             1970
  15#define SECDAY                  86400L
  16#define SECYR                   (SECDAY * 365)
  17#define leapyear(year)          ((year) % 4 == 0)
  18#define days_in_year(a)         (leapyear(a) ? 366 : 365)
  19#define days_in_month(a)        (month_days[(a) - 1])
  20
  21static int month_offset[] = {
  22        0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  23};
  24
  25/*
  26 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
  27 */
  28int rtc_calc_weekday(struct rtc_time *tm)
  29{
  30        int leaps_to_date;
  31        int last_year;
  32        int day;
  33
  34        if (tm->tm_year < 1753)
  35                return -1;
  36        last_year = tm->tm_year - 1;
  37
  38        /* Number of leap corrections to apply up to end of last year */
  39        leaps_to_date = last_year / 4 - last_year / 100 + last_year / 400;
  40
  41        /*
  42         * This year is a leap year if it is divisible by 4 except when it is
  43         * divisible by 100 unless it is divisible by 400
  44         *
  45         * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 is.
  46         */
  47        if (tm->tm_year % 4 == 0 &&
  48            ((tm->tm_year % 100 != 0) || (tm->tm_year % 400 == 0)) &&
  49            tm->tm_mon > 2) {
  50                /* We are past Feb. 29 in a leap year */
  51                day = 1;
  52        } else {
  53                day = 0;
  54        }
  55
  56        day += last_year * 365 + leaps_to_date + month_offset[tm->tm_mon - 1] +
  57                        tm->tm_mday;
  58        tm->tm_wday = day % 7;
  59
  60        return 0;
  61}
  62
  63/*
  64 * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
  65 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
  66 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
  67 *
  68 * [For the Julian calendar (which was used in Russia before 1917,
  69 * Britain & colonies before 1752, anywhere else before 1582,
  70 * and is still in use by some communities) leave out the
  71 * -year / 100 + year / 400 terms, and add 10.]
  72 *
  73 * This algorithm was first published by Gauss (I think).
  74 */
  75time64_t rtc_mktime(const struct rtc_time *tm)
  76{
  77        int mon = tm->tm_mon;
  78        int year = tm->tm_year;
  79        unsigned long days;
  80        time64_t hours;
  81
  82        mon -= 2;
  83        if (0 >= mon) {         /* 1..12 -> 11, 12, 1..10 */
  84                mon += 12;      /* Puts Feb last since it has leap day */
  85                year -= 1;
  86        }
  87
  88        days = (unsigned long)(year / 4 - year / 100 + year / 400 +
  89                        367 * mon / 12 + tm->tm_mday) +
  90                        year * 365 - 719499;
  91        hours = days * 24 + tm->tm_hour;
  92        return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec;
  93}
  94
  95/* for compatibility with linux code */
  96time64_t mktime64(const unsigned int year, const unsigned int mon,
  97                  const unsigned int day, const unsigned int hour,
  98                  const unsigned int min, const unsigned int sec)
  99{
 100        struct rtc_time time;
 101
 102        time.tm_year = year;
 103        time.tm_mon = mon;
 104        time.tm_mday = day;
 105        time.tm_hour = hour;
 106        time.tm_min = min;
 107        time.tm_sec = sec;
 108
 109        return rtc_mktime((const struct rtc_time *)&time);
 110}
 111