1 // SPDX-License-Identifier: LGPL-2.0+
19  * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20  * Boston, MA 02111-1307, USA.
24  * Converts the calendar time to broken-down time representation
25  * Based on code from glibc-2.6
27  * 2009-7-14:
28  *   Moved from glibc-2.6 to kernel by Zhaolei<zhaolei@cn.fujitsu.com>
46 	return a / b - (a % b < 0);  in math_div()
52 	long leaps1 = math_div(y1 - 1, 4) - math_div(y1 - 1, 100)  in leaps_between()
53 		+ math_div(y1 - 1, 400);  in leaps_between()
54 	long leaps2 = math_div(y2 - 1, 4) - math_div(y2 - 1, 100)  in leaps_between()
55 		+ math_div(y2 - 1, 400);  in leaps_between()
56 	return leaps2 - leaps1;  in leaps_between()
59 /* How many days come before each month (0-12). */
71  * time64_to_tm - converts the calendar time to local broken-down time
75  * @offset	offset seconds adding to totalsecs.
76  * @result	pointer to struct tm variable to receive broken-down time
78 void time64_to_tm(time64_t totalsecs, int offset, struct tm *result)  in time64_to_tm()  argument
80 	long days, rem, y;  in time64_to_tm()  local
86 	rem += offset;  in time64_to_tm()
89 		--days;  in time64_to_tm()
92 		rem -= SECS_PER_DAY;  in time64_to_tm()
96 	result->tm_hour = rem / SECS_PER_HOUR;  in time64_to_tm()
98 	result->tm_min = rem / 60;  in time64_to_tm()
99 	result->tm_sec = rem % 60;  in time64_to_tm()
102 	result->tm_wday = (4 + days) % 7;  in time64_to_tm()
103 	if (result->tm_wday < 0)  in time64_to_tm()
104 		result->tm_wday += 7;  in time64_to_tm()
106 	y = 1970;  in time64_to_tm()
108 	while (days < 0 || days >= (__isleap(y) ? 366 : 365)) {  in time64_to_tm()
110 		long yg = y + math_div(days, 365);  in time64_to_tm()
112 		/* Adjust DAYS and Y to match the guessed year. */  in time64_to_tm()
113 		days -= (yg - y) * 365 + leaps_between(y, yg);  in time64_to_tm()
114 		y = yg;  in time64_to_tm()
117 	result->tm_year = y - 1900;  in time64_to_tm()
119 	result->tm_yday = days;  in time64_to_tm()
121 	ip = __mon_yday[__isleap(y)];  in time64_to_tm()
122 	for (y = 11; days < ip[y]; y--)  in time64_to_tm()
124 	days -= ip[y];  in time64_to_tm()
126 	result->tm_mon = y;  in time64_to_tm()
127 	result->tm_mday = days + 1;  in time64_to_tm()