156 lines
4.3 KiB
C
156 lines
4.3 KiB
C
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/***
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*gmtime64.c - breaks down a time value into GMT date/time info
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*
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* Copyright (c) 1998-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines _gmtime64() - breaks the clock value down into GMT time/date
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* information; returns pointer to structure with the data.
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*
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*Revision History:
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* 05-13-98 GJF Created. Adapted from Win64 version of _gmtime64.c.
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* 06-12-98 GJF Fixed elapsed years calculation.
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*
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*******************************************************************************/
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#include <cruntime.h>
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#include <time.h>
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#include <ctime.h>
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#include <stddef.h>
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#include <internal.h>
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#include <mtdll.h>
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#ifdef _MT
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#include <malloc.h>
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#include <stddef.h>
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#endif
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#include <dbgint.h>
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static struct tm tb = { 0 }; /* time block */
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/***
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*struct tm *_gmtime64(timp) - convert *timp to a structure (UTC)
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*
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*Purpose:
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* Converts the calendar time value, in internal 64-bit format to
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* broken-down time (tm structure) with the corresponding UTC time.
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*
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*Entry:
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* const __time64_t *timp - pointer to time_t value to convert
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*
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*Exit:
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* returns pointer to filled-in tm structure.
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* returns NULL if *timp < 0
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*
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*Exceptions:
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*
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*******************************************************************************/
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struct tm * __cdecl _gmtime64 (
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const __time64_t *timp
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)
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{
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__time64_t caltim = *timp; /* calendar time to convert */
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int islpyr = 0; /* is-current-year-a-leap-year flag */
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int tmptim;
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int *mdays; /* pointer to days or lpdays */
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#ifdef _MT
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struct tm *ptb; /* will point to gmtime buffer */
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_ptiddata ptd = _getptd();
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#else
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struct tm *ptb = &tb;
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#endif
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if ( (caltim < 0) || (caltim > _MAX__TIME64_T) )
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return(NULL);
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#ifdef _MT
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/* Use per thread buffer area (malloc space, if necessary) */
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if ( (ptd->_gmtimebuf != NULL) || ((ptd->_gmtimebuf =
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_malloc_crt(sizeof(struct tm))) != NULL) )
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ptb = ptd->_gmtimebuf;
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else
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ptb = &tb; /* malloc error: use static buffer */
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#endif
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/*
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* Determine the years since 1900. Start by ignoring leap years.
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*/
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tmptim = (int)(caltim / _YEAR_SEC) + 70;
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caltim -= ((__time64_t)(tmptim - 70) * _YEAR_SEC);
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/*
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* Correct for elapsed leap years
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*/
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caltim -= ((__time64_t)_ELAPSED_LEAP_YEARS(tmptim) * _DAY_SEC);
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/*
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* If we have underflowed the __time64_t range (i.e., if caltim < 0),
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* back up one year, adjusting the correction if necessary.
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*/
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if ( caltim < 0 ) {
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caltim += (__time64_t)_YEAR_SEC;
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tmptim--;
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if ( _IS_LEAP_YEAR(tmptim) ) {
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caltim += _DAY_SEC;
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islpyr++;
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}
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}
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else
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if ( _IS_LEAP_YEAR(tmptim) )
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islpyr++;
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/*
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* tmptim now holds the value for tm_year. caltim now holds the
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* number of elapsed seconds since the beginning of that year.
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*/
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ptb->tm_year = tmptim;
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/*
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* Determine days since January 1 (0 - 365). This is the tm_yday value.
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* Leave caltim with number of elapsed seconds in that day.
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*/
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ptb->tm_yday = (int)(caltim / _DAY_SEC);
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caltim -= (__time64_t)(ptb->tm_yday) * _DAY_SEC;
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/*
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* Determine months since January (0 - 11) and day of month (1 - 31)
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*/
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if ( islpyr )
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mdays = _lpdays;
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else
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mdays = _days;
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for ( tmptim = 1 ; mdays[tmptim] < ptb->tm_yday ; tmptim++ ) ;
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ptb->tm_mon = --tmptim;
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ptb->tm_mday = ptb->tm_yday - mdays[tmptim];
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/*
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* Determine days since Sunday (0 - 6)
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*/
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ptb->tm_wday = ((int)(*timp / _DAY_SEC) + _BASE_DOW) % 7;
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/*
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* Determine hours since midnight (0 - 23), minutes after the hour
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* (0 - 59), and seconds after the minute (0 - 59).
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*/
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ptb->tm_hour = (int)(caltim / 3600);
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caltim -= (__time64_t)ptb->tm_hour * 3600L;
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ptb->tm_min = (int)(caltim / 60);
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ptb->tm_sec = (int)(caltim - (ptb->tm_min) * 60);
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ptb->tm_isdst = 0;
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return( (struct tm *)ptb );
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}
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