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/*
* gmtime_r.c
* Original Author: Adapted from tzcode maintained by Arthur David Olson.
* Modifications:
* - Changed to mktm_r and added __tzcalc_limits - 04/10/02, Jeff Johnston
* - Fixed bug in mday computations - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
* - Fixed bug in __tzcalc_limits - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
* - Move code from _mktm_r() to gmtime_r() - 05/09/14, Freddie Chopin <freddie_chopin@op.pl>
*
* Converts the calendar time pointed to by tim_p into a broken-down time
* expressed as local time. Returns a pointer to a structure containing the
* broken-down time.
*/
#include "local.h"
/* there are 97 leap years in 400-year periods. ((400 - 97) * 365 + 97 * 366) */
#define DAYS_PER_400_YEARS 146097L
/* there are 24 leap years in 100-year periods. ((100 - 24) * 365 + 24 * 366) */
#define DAYS_PER_100_YEARS 36524L
/* there is one leap year every 4 years */
#define DAYS_PER_4_YEARS (3 * 365 + 366)
static _CONST int days_per_year[4] = {
365, /* 1970 or 1966 */
365, /* 1971 or 1967 */
366, /* 1972 or 1968 */
365 /* 1973 or 1969 */
} ;
struct tm *
_DEFUN (gmtime_r, (tim_p, res),
_CONST time_t *__restrict tim_p _AND
struct tm *__restrict res)
{
long days, rem;
_CONST time_t lcltime = *tim_p;
int year;
int years400, years100, years4;
int yearleap;
_CONST int *ip;
days = ((long)lcltime) / SECSPERDAY;
rem = ((long)lcltime) % SECSPERDAY;
while (rem < 0)
{
rem += SECSPERDAY;
--days;
}
/* compute hour, min, and sec */
res->tm_hour = (int) (rem / SECSPERHOUR);
rem %= SECSPERHOUR;
res->tm_min = (int) (rem / SECSPERMIN);
res->tm_sec = (int) (rem % SECSPERMIN);
/* compute day of week */
if ((res->tm_wday = ((EPOCH_WDAY + days) % DAYSPERWEEK)) < 0)
res->tm_wday += DAYSPERWEEK;
/* compute year & day of year */
years400 = days / DAYS_PER_400_YEARS;
days -= years400 * DAYS_PER_400_YEARS;
years100 = days / DAYS_PER_100_YEARS;
days -= years100 * DAYS_PER_100_YEARS;
years4 = days / DAYS_PER_4_YEARS;
days -= years4 * DAYS_PER_4_YEARS;
year = EPOCH_YEAR + years400 * 400 + years100 * 100 + years4 * 4;
/* the value left in days is based in 1970 */
if (days < 0)
{
ip = &days_per_year[3];
while (days < 0)
{
days += *ip--;
--year;
}
}
else
{
ip = &days_per_year[0];
while (days >= *ip)
{
days -= *ip++;
++year;
}
}
res->tm_year = year - YEAR_BASE;
res->tm_yday = days;
yearleap = isleap(year);
ip = __month_lengths[yearleap];
for (res->tm_mon = 0; days >= ip[res->tm_mon]; ++res->tm_mon)
days -= ip[res->tm_mon];
res->tm_mday = days + 1;
res->tm_isdst = 0;
return (res);
}
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