reactos/lib/sdk/crt/time/gmtime.c

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/*
* COPYRIGHT: LGPL, See LGPL.txt in the top level directory
* PROJECT: ReactOS CRT library
* FILE: lib/sdk/crt/time/gmtime.c
* PURPOSE: Implementation of gmtime, _gmtime32, _gmtime64
* PROGRAMERS: Timo Kreuzer
*/
#include <precomp.h>
unsigned int g_monthdays[13] = {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365};
unsigned int g_lpmonthdays[13] = {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366};
struct tm *
_gmtime_worker(struct tm *ptm, __time64_t time, int do_dst)
{
unsigned int days, daystoyear, dayinyear, leapdays, leapyears, years, month;
unsigned int secondinday, secondinhour;
unsigned int *padays;
if (time < 0)
{
return 0;
}
/* Divide into date and time */
days = time / SECONDSPERDAY;
secondinday = time % SECONDSPERDAY;
/* Shift to days from 1.1.1601 */
days += DIFFDAYS;
/* Calculate leap days passed till today */
leapdays = leapdays_passed(days);
/* Calculate number of full leap years passed */
leapyears = leapyears_passed(days);
/* Are more leap days passed than leap years? */
if (leapdays > leapyears)
{
/* Yes, we're in a leap year */
padays = g_lpmonthdays;
}
else
{
/* No, normal year */
padays = g_monthdays;
}
/* Calculate year */
years = (days - leapdays) / 365;
ptm->tm_year = years - 299;
/* Calculate number of days till 1.1. of this year */
daystoyear = years * 365 + leapyears;
/* Calculate the day in this year */
dayinyear = days - daystoyear;
/* Shall we do DST corrections? */
ptm->tm_isdst = 0;
if (do_dst)
{
unsigned int yeartime = dayinyear * SECONDSPERDAY + secondinday ;
if (yeartime >= dst_begin && yeartime <= dst_end) // FIXME! DST in winter
{
time -= _dstbias;
days = time / SECONDSPERDAY + DIFFDAYS;
dayinyear = days - daystoyear;
ptm->tm_isdst = 1;
}
}
ptm->tm_yday = dayinyear;
/* dayinyear < 366 => terminates with i <= 11 */
for (month = 0; dayinyear >= padays[month+1]; month++)
;
/* Set month and day in month */
ptm->tm_mon = month;
ptm->tm_mday = 1 + dayinyear - padays[month];
/* Get weekday */
ptm->tm_wday = (days + 1) % 7;
/* Calculate hour and second in hour */
ptm->tm_hour = secondinday / SECONDSPERHOUR;
secondinhour = secondinday % SECONDSPERHOUR;
/* Calculate minute and second */
ptm->tm_min = secondinhour / 60;
ptm->tm_sec = secondinhour % 60;
return ptm;
}
/******************************************************************************
* \name _gmtime64
* \brief
* \param ptime Pointer to a variable of type __time64_t containing the time.
*/
struct tm *
_gmtime64(const __time64_t * ptime)
{
PTHREADDATA pThreadData;
struct tm *ptm;
__time64_t time = *ptime;
/* Validate parameters */
if (time < 0)
{
return 0;
}
/* Get pointer to TLS tm buffer */
pThreadData = GetThreadData();
ptm = &pThreadData->tmbuf;
/* Use _gmtime_worker to do the ral work */
return _gmtime_worker(ptm, time, 0);
}
/******************************************************************************
* \name _gmtime32
* \brief
* \param ptime Pointer to a variable of type __time32_t containing the time.
*/
struct tm *
_gmtime32(const __time32_t * ptime)
{
__time64_t time64 = (__time64_t)*ptime;
return _gmtime64(&time64);
}
/******************************************************************************
* \name gmtime
* \brief
* \param ptime Pointer to a variable of type time_t containing the time.
*/
struct tm *
gmtime(const time_t * ptime)
{
__time64_t time64 = (__time64_t)*ptime;
return _gmtime64(&time64);
}