3 /* C defines the rounding for division in a nonsensical way */
4 #define Q(a,b) ((a)>0 ? (a)/(b) : -(((b)-(a)-1)/(b)))
6 #define DAYS_PER_400Y (365*400 + 97)
7 #define DAYS_PER_100Y (365*100 + 24)
8 #define DAYS_PER_4Y (365*4 + 1)
10 /* FIXME: use lldiv once it's fixed to compute quot,rem together */
11 struct tm *__time_to_tm(time_t t, struct tm *tm)
13 /* months are march-based */
14 static const int days_thru_month[] = {31,61,92,122,153,184,214,245,275,306,337,366};
16 unsigned int day, year4, year100;
23 /* start from 2000-03-01 (multiple of 400 years) */
24 t += -946684800 - 86400*(31+29);
34 /* 2000-03-01 was a wednesday */
36 if (wday < 0) wday += 7;
38 t = -946684800LL - 86400*(31+29) + 9000000;
40 year400 = Q(bigday, DAYS_PER_400Y);
41 day = bigday-year400*DAYS_PER_400Y;
43 year100 = day/DAYS_PER_100Y;
44 if (year100 == 4) year100--;
45 day -= year100*DAYS_PER_100Y;
47 year4 = day/DAYS_PER_4Y;
48 if (year4 == 25) year4--;
49 day -= year4*DAYS_PER_4Y;
52 if (year == 4) year--;
55 leap = !year && (year4 || !year100);
56 yday = day + 31+28 + leap;
57 if (yday >= 365+leap) yday -= 365+leap;
59 year += 4*year4 + 100*year100 + 400*year400 + 2000-1900;
61 for (month=0; days_thru_month[month] <= day; month++);
62 if (month) day -= days_thru_month[month-1];