1 // SPDX-License-Identifier: GPL-2.0+
21 #define	days_in_month(a)	(month_days[(a) - 1])
28  * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
36 	if (tm->tm_year < 1753)  in rtc_calc_weekday()
37 		return -1;  in rtc_calc_weekday()
38 	last_year = tm->tm_year - 1;  in rtc_calc_weekday()
41 	leaps_to_date = last_year / 4 - last_year / 100 + last_year / 400;  in rtc_calc_weekday()
49 	if (tm->tm_year % 4 == 0 &&  in rtc_calc_weekday()
50 	    ((tm->tm_year % 100 != 0) || (tm->tm_year % 400 == 0)) &&  in rtc_calc_weekday()
51 	    tm->tm_mon > 2) {  in rtc_calc_weekday()
58 	day += last_year * 365 + leaps_to_date + month_offset[tm->tm_mon - 1] +  in rtc_calc_weekday()
59 			tm->tm_mday;  in rtc_calc_weekday()
60 	tm->tm_wday = day % 7;  in rtc_calc_weekday()
66  * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
67  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
73  * -year / 100 + year / 400 terms, and add 10.]
77  * WARNING: this function will overflow on 2106-02-07 06:28:16 on
78  * machines where long is 32-bit! (However, as time_t is signed, we
79  * will already get problems at other places on 2038-01-19 03:14:08)
83 	int mon = tm->tm_mon;  in rtc_mktime()
84 	int year = tm->tm_year;  in rtc_mktime()
85 	int days, hours;  in rtc_mktime()  local
87 	mon -= 2;  in rtc_mktime()
88 	if (0 >= (int)mon) {	/* 1..12 -> 11, 12, 1..10 */  in rtc_mktime()
90 		year -= 1;  in rtc_mktime()
93 	days = (unsigned long)(year / 4 - year / 100 + year / 400 +  in rtc_mktime()
94 			367 * mon / 12 + tm->tm_mday) +  in rtc_mktime()
95 			year * 365 - 719499;  in rtc_mktime()
96 	hours = days * 24 + tm->tm_hour;  in rtc_mktime()
97 	return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec;  in rtc_mktime()