| /* Originally released by the musl project (http://www.musl-libc.org/) under the |
| * MIT license. Taken from the file /src/time/__secs_to_tm.c */ |
| |
| #include <limits.h> |
| #include "libc_time.h" |
| |
| /* 2000-03-01 (mod 400 year, immediately after feb29 */ |
| #define LEAPOCH (946684800LL + 86400*(31+29)) |
| |
| #define DAYS_PER_400Y (365*400 + 97) |
| #define DAYS_PER_100Y (365*100 + 24) |
| #define DAYS_PER_4Y (365*4 + 1) |
| |
| int __secs_to_tm(long long t, struct mytm *tm) { |
| long long days, secs, years; |
| int remdays, remsecs, remyears; |
| int qc_cycles, c_cycles, q_cycles; |
| int months; |
| int wday, yday, leap; |
| static const char days_in_month[] = {31,30,31,30,31,31,30,31,30,31,31,29}; |
| |
| /* Reject time_t values whose year would overflow int */ |
| if (t < INT_MIN * 31622400LL || t > INT_MAX * 31622400LL) |
| return -1; |
| |
| secs = t - LEAPOCH; |
| days = secs / 86400LL; |
| remsecs = (int)(secs % 86400); |
| if (remsecs < 0) { |
| remsecs += 86400; |
| --days; |
| } |
| |
| wday = (int)((3+days)%7); |
| if (wday < 0) wday += 7; |
| |
| qc_cycles = (int)(days / DAYS_PER_400Y); |
| remdays = (int)(days % DAYS_PER_400Y); |
| if (remdays < 0) { |
| remdays += DAYS_PER_400Y; |
| --qc_cycles; |
| } |
| |
| c_cycles = remdays / DAYS_PER_100Y; |
| if (c_cycles == 4) --c_cycles; |
| remdays -= c_cycles * DAYS_PER_100Y; |
| |
| q_cycles = remdays / DAYS_PER_4Y; |
| if (q_cycles == 25) --q_cycles; |
| remdays -= q_cycles * DAYS_PER_4Y; |
| |
| remyears = remdays / 365; |
| if (remyears == 4) --remyears; |
| remdays -= remyears * 365; |
| |
| leap = !remyears && (q_cycles || !c_cycles); |
| yday = remdays + 31 + 28 + leap; |
| if (yday >= 365+leap) yday -= 365+leap; |
| |
| years = remyears + 4*q_cycles + 100*c_cycles + 400LL*qc_cycles; |
| |
| for (months=0; days_in_month[months] <= remdays; ++months) |
| remdays -= days_in_month[months]; |
| |
| if (years+100 > INT_MAX || years+100 < INT_MIN) |
| return -1; |
| |
| tm->tm_year = (int)(years + 100); |
| tm->tm_mon = months + 2; |
| if (tm->tm_mon >= 12) { |
| tm->tm_mon -=12; |
| ++tm->tm_year; |
| } |
| tm->tm_mday = remdays + 1; |
| tm->tm_wday = wday; |
| tm->tm_yday = yday; |
| |
| tm->tm_hour = remsecs / 3600; |
| tm->tm_min = remsecs / 60 % 60; |
| tm->tm_sec = remsecs % 60; |
| |
| return 0; |
| } |
| |
| int __month_to_secs(int month, int is_leap) { |
| static const int secs_through_month[] = |
| {0, 31*86400, 59*86400, 90*86400, |
| 120*86400, 151*86400, 181*86400, 212*86400, |
| 243*86400, 273*86400, 304*86400, 334*86400 }; |
| int t = secs_through_month[month]; |
| if (is_leap && month >= 2) |
| t+=86400; |
| return t; |
| } |
| |
| long long __year_to_secs(long long year, int *is_leap) { |
| if (year-(int)2ULL <= 136) { |
| long long y = (int)year; |
| long long leaps = (y-68)>>2; |
| if (!((y-8)&3)) { |
| leaps--; |
| if (is_leap) *is_leap = 1; |
| } else if (is_leap) *is_leap = 0; |
| return 31536000*(y-70) + 86400*leaps; |
| } |
| |
| int cycles, centuries, leaps, rem; |
| |
| //if (!is_leap) is_leap = &(int){0}; |
| int is_leap_val = 0; |
| if (!is_leap) { |
| is_leap = &is_leap_val; |
| } |
| cycles = (int)((year-100) / 400); |
| rem = (int)((year-100) % 400); |
| /* Comparison is always false because rem >= 0. |
| if (rem < 0) { |
| cycles--; |
| rem += 400; |
| } */ |
| if (!rem) { |
| *is_leap = 1; |
| centuries = 0; |
| leaps = 0; |
| } else { |
| if (rem >= 200) { |
| if (rem >= 300) centuries = 3, rem -= 300; |
| else centuries = 2, rem -= 200; |
| } else { |
| if (rem >= 100) centuries = 1, rem -= 100; |
| else centuries = 0; |
| } |
| if (!rem) { |
| *is_leap = 0; |
| leaps = 0; |
| } else { |
| leaps = (rem / (int)4U); |
| rem %= (int)4U; |
| *is_leap = !rem; |
| } |
| } |
| |
| leaps += 97*cycles + 24*centuries - *is_leap; |
| |
| return (year-100) * 31536000LL + leaps * 86400LL + 946684800 + 86400; |
| } |
| |
| long long __tm_to_secs(const struct mytm *tm) { |
| int is_leap; |
| long long year = tm->tm_year; |
| int month = tm->tm_mon; |
| if (month >= 12 || month < 0) { |
| int adj = month / 12; |
| month %= 12; |
| if (month < 0) { |
| adj--; |
| month += 12; |
| } |
| year += adj; |
| } |
| long long t = __year_to_secs(year, &is_leap); |
| t += __month_to_secs(month, is_leap); |
| t += 86400LL * (tm->tm_mday-1); |
| t += 3600LL * tm->tm_hour; |
| t += 60LL * tm->tm_min; |
| t += tm->tm_sec; |
| return t; |
| } |