158 lines
5.1 KiB
C
158 lines
5.1 KiB
C
/***
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*ftime.c - return system time
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*
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* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* Returns the system date/time in a structure form.
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*
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*Revision History:
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* 03-??-84 RLB initial version
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* 05-17-86 SKS ported to OS/2
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* 03-09-87 SKS correct Daylight Savings Time flag
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* 11-18-87 SKS Change tzset() to __tzset()
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* 12-11-87 JCR Added "_LOAD_DS" to declaration
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* 10-03-88 JCR 386: Change DOS calls to SYS calls
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* 10-04-88 JCR 386: Removed 'far' keyword
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* 10-10-88 GJF Made API names match DOSCALLS.H
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* 04-12-89 JCR New syscall interface
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* 05-25-89 JCR 386 OS/2 calls use '_syscall' calling convention
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* 03-20-90 GJF Replaced _LOAD_DS with _CALLTYPE1, added #include
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* <cruntime.h>, removed some leftover 16-bit support
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* and fixed the copyright. Also, cleaned up the
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* formatting a bit.
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* 07-25-90 SBM Removed '32' from API names
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* 08-13-90 SBM Compiles cleanly with -W3
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* 08-20-90 SBM Removed old incorrect, redundant tp->dstflag assignment
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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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* 01-21-91 GJF ANSI naming.
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* 01-23-92 GJF Change in time zone field name for Win32, to support
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* crtdll.dll [_WIN32_].
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* 03-30-93 GJF Revised to use mktime(). Also purged Cruiser support.
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* 04-06-93 SKS Replace _CRTAPI* with __cdecl
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* 04-07-93 SKS Add _CRTIMP keyword for CRT DLL model
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* Restore correct spelling of "timezone" struct member.
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* 07-15-93 GJF Call __tzset() instead of _tzset().
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* 02-10-95 GJF Appended Mac version of source file (somewhat cleaned
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* up), with appropriate #ifdef-s.
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* 01-15-98 GJF Complete rewrite of _ftime to eliminate incorrect dst
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* status during the fall-back hour.
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* 05-17-99 PML Remove all Macintosh support.
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* 10-27-99 GB Remove #inlcude <dostypes.h>
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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 <sys/types.h>
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#include <sys/timeb.h>
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#include <time.h>
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#include <msdos.h>
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#include <dos.h>
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#include <stdlib.h>
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#include <windows.h>
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#include <internal.h>
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/*
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* Number of 100 nanosecond units from 1/1/1601 to 1/1/1970
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*/
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#define EPOCH_BIAS 116444736000000000i64
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/*
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* Union to facilitate converting from FILETIME to unsigned __int64
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*/
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typedef union {
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unsigned __int64 ft_scalar;
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FILETIME ft_struct;
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} FT;
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/*
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* Cache for the minutes count for with DST status was last assessed
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*/
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static time_t elapsed_minutes_cache = 0;
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/*
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* Three values of dstflag_cache
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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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/*
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* Cache for the last determined DST status
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*/
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static int dstflag_cache = UNKNOWN_TIME;
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/***
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*void _ftime(timeptr) - return DOS time in a structure
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*
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*Purpose:
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* returns the current DOS time in a struct timeb structure
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*
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*Entry:
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* struct timeb *timeptr - structure to fill in with time
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*
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*Exit:
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* no return value -- fills in structure
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*
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*Exceptions:
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*
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*******************************************************************************/
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_CRTIMP void __cdecl _ftime (
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struct _timeb *tp
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)
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{
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FT nt_time;
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time_t t;
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TIME_ZONE_INFORMATION tzinfo;
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DWORD tzstate;
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__tzset();
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tp->timezone = (short)(_timezone / 60);
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GetSystemTimeAsFileTime( &(nt_time.ft_struct) );
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/*
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* Obtain the current DST status. Note the status is cached and only
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* updated once per minute, if necessary.
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*/
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if ( (t = (time_t)(nt_time.ft_scalar / 600000000i64))
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!= elapsed_minutes_cache )
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{
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if ( (tzstate = GetTimeZoneInformation( &tzinfo )) != 0xFFFFFFFF )
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{
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/*
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* Must be very careful in determining whether or not DST is
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* really in effect.
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*/
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if ( (tzstate == TIME_ZONE_ID_DAYLIGHT) &&
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(tzinfo.DaylightDate.wMonth != 0) &&
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(tzinfo.DaylightBias != 0) )
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dstflag_cache = DAYLIGHT_TIME;
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else
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/*
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* When in doubt, assume standard time
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*/
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dstflag_cache = STANDARD_TIME;
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}
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else
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dstflag_cache = UNKNOWN_TIME;
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elapsed_minutes_cache = t;
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}
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tp->dstflag = (short)dstflag_cache;
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tp->millitm = (unsigned short)((nt_time.ft_scalar / 10000i64) %
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1000i64);
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tp->time = (time_t)((nt_time.ft_scalar - EPOCH_BIAS) / 10000000i64);
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}
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#endif /* _POSIX_ */
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