Re: Here, the debugger says: =?UTF-8?B?4oCcIFdhaXRlZCA9PSAuMDA1MA==?= =?UTF-8?B?MCDigJ0gc2Vjb25kcy4=?=

From:
"Tom Widmer [VC++ MVP]" <tom_usenet@hotmail.com>
Newsgroups:
microsoft.public.vc.language
Date:
Wed, 26 Sep 2007 12:03:35 +0100
Message-ID:
<eoTgjzCAIHA.4476@TK2MSFTNGP06.phx.gbl>
Jeff???Relf wrote:

You can wait for 5 milliseconds this way:

#include <Windows.H>

#pragma warning( disable: \
  4007 4101 4189 4244 4305 4430 4508 4706 4709 4996 )

#define Tics ( QueryPerformanceCounter( ( DubInt * ) & _Tics ), _Tics )

#define Secs ( _Secs = Tics / Secnd_Dub )

typedef LARGE_INTEGER DubInt ;
__int64 _Tics, Secnd ; double _Secs, Secnd_Dub ;


Names beginning with an _ and a capital letter are reserved for the
implementation (e.g. there may undocumented symbols with these names in
the system headers).

int __stdcall WinMain( HINSTANCE, HINSTANCE, char*, int ) {
  QueryPerformanceFrequency( ( DubInt * ) & Secnd ); Secnd_Dub = Secnd ;
  double Start = Secs ;

  while ( Secs < Start + .005 );
  float Waited = _Secs - Start ;
} // Here, the debugger says: ??? Waited == .00500 ??? seconds.


Note that this implements a busy wait, which might not be desireable on
a multitasking OS like Windows. Jochen's solution (call
timeBeginPeriod(1) prior to Sleep(5)) is good if 1-2 ms accuracy is
sufficient. You could also boost the priority of your process and thread
if you need more reliability in your timing (See SetPriorityClass and
SetThreadPriority).

Tom

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