3 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 * SPDX-License-Identifier: GPL-2.0+
9 * Date & Time support for Philips PCF8563 RTC
16 #if defined(CONFIG_CMD_DATE) || defined(CONFIG_TIMESTAMP)
19 #define STARTOFTIME 1970
21 #define SECYR (SECDAY * 365)
22 #define leapyear(year) ((year) % 4 == 0)
23 #define days_in_year(a) (leapyear(a) ? 366 : 365)
24 #define days_in_month(a) (month_days[(a) - 1])
26 static int month_days[12] = {
27 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
31 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
33 void GregorianDay(struct rtc_time * tm)
38 int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 };
40 lastYear=tm->tm_year-1;
43 * Number of leap corrections to apply up to end of last year
45 leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;
48 * This year is a leap year if it is divisible by 4 except when it is
49 * divisible by 100 unless it is divisible by 400
51 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be
53 if((tm->tm_year%4==0) &&
54 ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
57 * We are past Feb. 29 in a leap year
64 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday;
69 void to_tm(int tim, struct rtc_time * tm)
72 register long hms, day;
77 /* Hours, minutes, seconds are easy */
78 tm->tm_hour = hms / 3600;
79 tm->tm_min = (hms % 3600) / 60;
80 tm->tm_sec = (hms % 3600) % 60;
82 /* Number of years in days */
83 for (i = STARTOFTIME; day >= days_in_year(i); i++) {
84 day -= days_in_year(i);
88 /* Number of months in days left */
89 if (leapyear(tm->tm_year)) {
90 days_in_month(FEBRUARY) = 29;
92 for (i = 1; day >= days_in_month(i); i++) {
93 day -= days_in_month(i);
95 days_in_month(FEBRUARY) = 28;
98 /* Days are what is left over (+1) from all that. */
99 tm->tm_mday = day + 1;
102 * Determine the day of week
107 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
108 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
109 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
111 * [For the Julian calendar (which was used in Russia before 1917,
112 * Britain & colonies before 1752, anywhere else before 1582,
113 * and is still in use by some communities) leave out the
114 * -year/100+year/400 terms, and add 10.]
116 * This algorithm was first published by Gauss (I think).
118 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
119 * machines were long is 32-bit! (However, as time_t is signed, we
120 * will already get problems at other places on 2038-01-19 03:14:08)
123 mktime (unsigned int year, unsigned int mon,
124 unsigned int day, unsigned int hour,
125 unsigned int min, unsigned int sec)
127 if (0 >= (int) (mon -= 2)) { /* 1..12 -> 11,12,1..10 */
128 mon += 12; /* Puts Feb last since it has leap day */
133 (unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) +
135 )*24 + hour /* now have hours */
136 )*60 + min /* now have minutes */
137 )*60 + sec; /* finally seconds */