__year_to_secs(long long year,int * is_leap)1 long long __year_to_secs(long long year, int *is_leap)
2 {
3 	if (year-2ULL <= 136) {
4 		int y = year;
5 		int leaps = (y-68)>>2;
6 		if (!((y-68)&3)) {
7 			leaps--;
8 			if (is_leap) *is_leap = 1;
9 		} else if (is_leap) *is_leap = 0;
10 		return 31536000*(y-70) + 86400*leaps;
11 	}
12 
13 	int cycles, centuries, leaps, rem;
14 
15 	if (!is_leap) is_leap = &(int){0};
16 	cycles = (year-100) / 400;
17 	rem = (year-100) % 400;
18 	if (rem < 0) {
19 		cycles--;
20 		rem += 400;
21 	}
22 	if (!rem) {
23 		*is_leap = 1;
24 		centuries = 0;
25 		leaps = 0;
26 	} else {
27 		if (rem >= 200) {
28 			if (rem >= 300) centuries = 3, rem -= 300;
29 			else centuries = 2, rem -= 200;
30 		} else {
31 			if (rem >= 100) centuries = 1, rem -= 100;
32 			else centuries = 0;
33 		}
34 		if (!rem) {
35 			*is_leap = 0;
36 			leaps = 0;
37 		} else {
38 			leaps = rem / 4U;
39 			rem %= 4U;
40 			*is_leap = !rem;
41 		}
42 	}
43 
44 	leaps += 97*cycles + 24*centuries - *is_leap;
45 
46 	return (year-100) * 31536000LL + leaps * 86400LL + 946684800 + 86400;
47 }
48