1long 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	{
14	int cycles, centuries, leaps, rem;
15
16	if (!is_leap) {
17		static int isleap = 0;
18		is_leap = &isleap;
19	}
20	cycles = (year-100) / 400;
21	rem = (year-100) % 400;
22	if (rem < 0) {
23		cycles--;
24		rem += 400;
25	}
26	if (!rem) {
27		*is_leap = 1;
28		centuries = 0;
29		leaps = 0;
30	} else {
31		if (rem >= 200) {
32			if (rem >= 300) centuries = 3, rem -= 300;
33			else centuries = 2, rem -= 200;
34		} else {
35			if (rem >= 100) centuries = 1, rem -= 100;
36			else centuries = 0;
37		}
38		if (!rem) {
39			*is_leap = 0;
40			leaps = 0;
41		} else {
42			leaps = rem / 4U;
43			rem %= 4U;
44			*is_leap = !rem;
45		}
46	}
47
48	leaps += 97*cycles + 24*centuries - *is_leap;
49
50	return (year-100) * 31536000LL + leaps * 86400LL + 946684800 + 86400;
51	}
52}
53