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#include <time.h>
/* C defines the rounding for division in a nonsensical way */
#define Q(a,b) ((a)>0 ? (a)/(b) : -(((b)-(a)-1)/(b)))
time_t __tm_to_time(struct tm *tm)
{
time_t year = tm->tm_year + -100;
int month = tm->tm_mon;
int day = tm->tm_mday;
int z4, z100, z400;
/* normalize month */
if (month >= 12) {
year += month/12;
month %= 12;
} else if (month < 0) {
year += month/12;
month %= 12;
if (month) {
month += 12;
year--;
}
}
z4 = Q(year - (month < 2), 4);
z100 = Q(z4, 25);
z400 = Q(z100, 4);
day += year*365 + z4 - z100 + z400 +
month[(int []){0,31,59,90,120,151,181,212,243,273,304,335}];
return (long long)day*86400
+ tm->tm_hour*3600 + tm->tm_min*60 + tm->tm_sec
- -946684800; /* the dawn of time :) */
}
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