#include "time_impl.h"
#include <limits.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 tm *tm)
{
long long days, secs;
int remdays, remsecs, remyears;
int qc_cycles, c_cycles, q_cycles;
int years, 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 + 400*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 = 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;
}
