__int64 comp_frequency;
__int64 start, end;
QueryPerformanceFrequency((LARGE_INTEGER *) &comp_frequency);
QueryPerformanceCounter((LARGE_INTEGER *) &start);
Sleep(3000);
QueryPerformanceCounter((LARGE_INTEGER *) &end);
float time = static_cast<float>((end-start)/comp_frequency);
cout << time << endl;
Trouble with int64s
Author
Konbon wa, I'm using int64s to hold values of my high frequency counter for purposes of timing in my game. Though I'm having trouble getting accurate results when debugging my code.
I have the following tidbit of code->
I'm not in windows at the moment, but try this
__int64 comp_frequency;__int64 start, end;QueryPerformanceFrequency((LARGE_INTEGER *) &comp_frequency);QueryPerformanceCounter((LARGE_INTEGER *) &start); Sleep(3000);QueryPerformanceCounter((LARGE_INTEGER *) &end); float time = static_cast<float>(end-start)/static_cast<float>(comp_frequency);cout << time << endl;
Author
Yes, Cocalus is right, though I still dont understand why his cast worked over mine. Basically my timer is always about ~10 ms seconds off, and this makes since, because sleep probably relies on GetTickCount, or a GetTime function, which has a 10 ms resolution, and therefore is always going to be off ~10 ms or so. It would be cool if we could get some other game deveres to try it out on their machines and compare results.
By the way I'm using Visual C++ 6.0, which is probably one of the reasons :)
By the way I'm using Visual C++ 6.0, which is probably one of the reasons :)
timeBeginPeriod
timeGetTime
timeEndPeriod
works for me as a high resolution timer down to 1ms on all the machines I've tried so far.
timeGetTime
timeEndPeriod
works for me as a high resolution timer down to 1ms on all the machines I've tried so far.
The reason the cast works is that in your case you're doing an integer (although int64) division which will throw away any reminder. Only the division result is casted to float.
If you cast one of the division participants to float before you'll get the "real" value.
VC6 is old, but it's not that bad. There won't be any difference to VC7 for that piece of code.
If you cast one of the division participants to float before you'll get the "real" value.
VC6 is old, but it's not that bad. There won't be any difference to VC7 for that piece of code.
Quote:Original post by ordered_disorder
Sleep probably relies on GetTickCount, or a GetTime function, which has a 10 ms resolution, and therefore is always going to be off ~10 ms or so.
That's part of it. Another is that Sleep just determines how long your process should be held in a sleep queue. Once that time has expired, Windows will put it back in the active queue, and *then* it'll be activated.... When it gets its turn.
That might be instantly, or it might be after 10 (or more) ms.
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
