Rich Felker | 1cc81f5 | 2013-07-17 05:24:50 -0400 | [diff] [blame] | 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 | } |