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176 lines
4.9 KiB
176 lines
4.9 KiB
/***
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*time.c - get current system time
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*
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* Copyright (c) 1989-1995, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines time() - gets the current system time and converts it to
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* internal (time_t) format time.
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*
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*Revision History:
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* 06-07-89 PHG Module created, based on asm version
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* 03-20-90 GJF Made calling type _CALLTYPE1, added #include
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* <cruntime.h> and fixed the copyright. Also, cleaned
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* up the formatting a bit.
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* 07-25-90 SBM Removed '32' from API names
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* 10-04-90 GJF New-style function declarator.
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* 12-04-90 SRW Changed to include <oscalls.h> instead of <doscalls.h>
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* 12-06-90 SRW Added _CRUISER_ and _WIN32 conditionals.
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* 05-19-92 DJM ifndef for POSIX build.
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* 03-30-93 GJF Replaced dtoxtime() reference by __gmtotime_t. Also
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* purged Cruiser support.
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* 04-06-93 SKS Replace _CRTAPI* with __cdecl
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* 07-21-93 GJF Converted from using __gmtotime_t and GetSystemTime,
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* to using __loctotime_t and GetLocalTime.
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* 02-13-95 GJF Merged in Mac version.
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* 09-22-95 GJF Obtain and use Win32's DST flag.
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* 10-24-95 GJF GetTimeZoneInformation is *EXPENSIVE* on NT. Use a
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* cache to minimize calls to this API.
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* 12-13-95 GJF Optimization above wasn't working because I had
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* switched gmt and gmt_cache (thanks PhilipLu!)
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*
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*******************************************************************************/
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#ifndef _POSIX_
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#include <cruntime.h>
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#include <time.h>
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#include <internal.h>
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#ifdef _WIN32
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#include <windows.h>
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#else
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#if defined(_M_MPPC) || defined(_M_M68K)
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#include <macos\osutils.h> /* get DataTimeRec type */
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#endif
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#endif
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#ifdef _WIN32
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/*
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* Cache holding the last time (GMT) for which the Daylight time status was
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* determined by an API call.
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*/
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static SYSTEMTIME gmt_cache;
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/*
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* Three values of dstflag_cache and dstflag (local variable in code
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* below)
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*/
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#define DAYLIGHT_TIME 1
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#define STANDARD_TIME 0
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#define UNKNOWN_TIME -1
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static int dstflag_cache;
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#endif
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/***
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*time_t time(timeptr) - Get current system time and convert to time_t value.
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*
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*Purpose:
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* Gets the current date and time and stores it in internal (time_t)
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* format. The time is returned and stored via the pointer passed in
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* timeptr. If timeptr == NULL, the time is only returned, not stored in
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* *timeptr. The internal (time_t) format is the number of seconds since
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* 00:00:00, Jan 1 1970 (UTC).
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*
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* Note: We cannot use GetSystemTime since its return is ambiguous. In
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* Windows NT, in return UTC. In Win32S, probably also Win32C, it
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* returns local time.
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*
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*Entry:
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* time_t *timeptr - pointer to long to store time in.
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*
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*Exit:
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* returns the current time.
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*
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*Exceptions:
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*
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*******************************************************************************/
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time_t __cdecl time (
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time_t *timeptr
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)
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{
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time_t tim;
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#ifdef _WIN32
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SYSTEMTIME loct, gmt;
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TIME_ZONE_INFORMATION tzinfo;
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DWORD tzstate;
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int dstflag;
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/*
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* Get local time from Win32
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*/
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GetLocalTime( &loct );
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/*
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* Determine whether or not the local time is a Daylight Saving
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* Time. On Windows NT, the GetTimeZoneInformation API is *VERY*
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* expensive. The scheme below is intended to avoid this API call in
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* many important case by caching the GMT value and dstflag.In a
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* subsequent call to time(), the cached value of dstflag is used
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* unless the new GMT differs from the cached value at least in the
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* minutes place.
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*/
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GetSystemTime( &gmt );
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if ( (gmt.wMinute == gmt_cache.wMinute) &&
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(gmt.wHour == gmt_cache.wHour) &&
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(gmt.wDay == gmt_cache.wDay) &&
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(gmt.wMonth == gmt_cache.wMonth) &&
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(gmt.wYear == gmt_cache.wYear) )
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{
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dstflag = dstflag_cache;
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}
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else
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{
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if ( (tzstate = GetTimeZoneInformation( &tzinfo )) ==
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TIME_ZONE_ID_DAYLIGHT )
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dstflag = DAYLIGHT_TIME;
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else if ( tzstate == TIME_ZONE_ID_STANDARD )
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dstflag = STANDARD_TIME;
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else
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dstflag = UNKNOWN_TIME;
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dstflag_cache = dstflag;
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gmt_cache = gmt;
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}
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/* convert using our private routine */
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tim = __loctotime_t( (int)loct.wYear,
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(int)loct.wMonth,
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(int)loct.wDay,
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(int)loct.wHour,
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(int)loct.wMinute,
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(int)loct.wSecond,
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dstflag );
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#else
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#if defined(_M_MPPC) || defined(_M_M68K)
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DateTimeRec dt;
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GetTime(&dt);
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/* convert using our private routine */
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tim = _gmtotime_t((int)dt.year,
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(int)dt.month,
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(int)dt.day,
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(int)dt.hour,
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dt.minute,
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dt.second);
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#endif
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#endif
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if (timeptr)
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*timeptr = tim; /* store time if requested */
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return tim;
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}
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#endif /* _POSIX_ */
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