#include "time_impl.h" #include /* 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 tm *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 / 86400; remsecs = secs % 86400; if (remsecs < 0) { remsecs += 86400; days--; } wday = (3+days)%7; if (wday < 0) wday += 7; qc_cycles = days / DAYS_PER_400Y; remdays = 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 (months >= 10) { months -= 12; years++; } if (years+100 > INT_MAX || years+100 < INT_MIN) return -1; tm->tm_year = years + 100; tm->tm_mon = months + 2; 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; }