/***
*gmtime.c - breaks down a time value into GMT date/time info
*
* Copyright (c) 1985-1993, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines gmtime() - breaks the clock value down into GMT time/date
* information; return pointer to structure with the data.
*
*Revision History:
* 01-??-84 RLB Module created
* 05-??-84 DCW Split off from rest off ctime routines.
* 02-18-87 JCR For MS C, gmtime now returns NULL for out of range
* time/date. (This is for ANSI compatibility.)
* 04-10-87 JCR Changed long declaration to time_t and added const
* 05-21-87 SKS Declare "struct tm tb" as NEAR data
* 11-10-87 SKS Removed IBMC20 switch
* 12-11-87 JCR Added "_LOAD_DS" to declaration
* 05-24-88 PHG Merge DLL and regular versions
* 06-06-89 JCR 386 mthread support
* 11-06-89 KRS Add (unsigned) to handle years 2040-2099 correctly
* 03-20-90 GJF Replaced _LOAD_DS with _CALLTYPE1, added #include
* <cruntime.h>, removed #include <register.h> and
* fixed the copyright. Also, cleaned up the formatting
* a bit.
* 10-04-90 GJF New-style function declarator.
* 07-17-91 GJF Multi-thread support for Win32 [_WIN32_].
* 02-17-93 GJF Changed for new _getptd().
* 03-24-93 GJF Propagated changes from 16-bit tree.
*
*******************************************************************************/
#include <cruntime.h>
#include <time.h>
#include <ctime.h>
#include <stddef.h>
#include <internal.h>
#include <os2dll.h>
#ifdef MTHREAD
#include <malloc.h>
#include <stddef.h>
#endif
static struct tm tb = { 0 }; /* time block */
/***
*struct tm *gmtime(timp) - convert *timp to a structure (UTC)
*
*Purpose:
* Converts the calendar time value, in internal format (time_t), to
* broken-down time (tm structure) with the corresponding UTC time.
*
*Entry:
* const time_t *timp - pointer to time_t value to convert
*
*Exit:
* returns pointer to filled-in tm structure.
* returns NULL if *timp < 0L
*
*Exceptions:
*
*******************************************************************************/
struct tm * _CRTAPI1 gmtime (
const time_t *timp
)
{
long caltim = *timp; /* calendar time to convert */
int islpyr = 0; /* is-current-year-a-leap-year flag */
REG1 int tmptim;
REG3 int *mdays; /* pointer to days or lpdays */
#ifdef MTHREAD
REG2 struct tm *ptb; /* will point to gmtime buffer */
_ptiddata ptd = _getptd();
#else
REG2 struct tm *ptb = &tb;
#endif
if ( caltim < 0L )
return(NULL);
#ifdef MTHREAD
/* Use per thread buffer area (malloc space, if necessary) */
if ( (ptd->_gmtimebuf != NULL) || ((ptd->_gmtimebuf =
malloc(sizeof(struct tm))) != NULL) )
ptb = ptd->_gmtimebuf;
else
ptb = &tb; /* malloc error: use static buffer */
#endif
/*
* Determine years since 1970. First, identify the four-year interval
* since this makes handling leap-years easy (note that 2000 IS a
* leap year and 2100 is out-of-range).
*/
tmptim = (int)(caltim / _FOUR_YEAR_SEC);
caltim -= ((long)tmptim * _FOUR_YEAR_SEC);
/*
* Determine which year of the interval
*/
tmptim = (tmptim * 4) + 70; /* 1970, 1974, 1978,...,etc. */
if ( caltim >= _YEAR_SEC ) {
tmptim++; /* 1971, 1975, 1979,...,etc. */
caltim -= _YEAR_SEC;
if ( caltim >= _YEAR_SEC ) {
tmptim++; /* 1972, 1976, 1980,...,etc. */
caltim -= _YEAR_SEC;
/*
* Note, it takes 366 days-worth of seconds to get past a leap
* year.
*/
if ( caltim >= (_YEAR_SEC + _DAY_SEC) ) {
tmptim++; /* 1973, 1977, 1981,...,etc. */
caltim -= (_YEAR_SEC + _DAY_SEC);
}
else {
/*
* In a leap year after all, set the flag.
*/
islpyr++;
}
}
}
/*
* tmptim now holds the value for tm_year. caltim now holds the
* number of elapsed seconds since the beginning of that year.
*/
ptb->tm_year = tmptim;
/*
* Determine days since January 1 (0 - 365). This is the tm_yday value.
* Leave caltim with number of elapsed seconds in that day.
*/
ptb->tm_yday = (int)(caltim / _DAY_SEC);
caltim -= (long)(ptb->tm_yday) * _DAY_SEC;
/*
* Determine months since January (0 - 11) and day of month (1 - 31)
*/
if ( islpyr )
mdays = _lpdays;
else
mdays = _days;
for ( tmptim = 1 ; mdays[tmptim] < ptb->tm_yday ; tmptim++ ) ;
ptb->tm_mon = --tmptim;
ptb->tm_mday = ptb->tm_yday - mdays[tmptim];
/*
* Determine days since Sunday (0 - 6)
*/
ptb->tm_wday = ((int)(*timp / _DAY_SEC) + _BASE_DOW) % 7;
/*
* Determine hours since midnight (0 - 23), minutes after the hour
* (0 - 59), and seconds after the minute (0 - 59).
*/
ptb->tm_hour = (int)(caltim / 3600);
caltim -= (long)ptb->tm_hour * 3600L;
ptb->tm_min = (int)(caltim / 60);
ptb->tm_sec = (int)(caltim - (ptb->tm_min) * 60);
ptb->tm_isdst = 0;
return( (struct tm *)ptb );
}
