timer hell ! need 13ms

This is a discussion on timer hell ! need 13ms within the Windows Programming forums, part of the Platform Specific Boards category; I desperately need to figure out the best method to get a 13ms timer. It doesn't need to be perfect, ...

  1. #1
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    timer hell ! need 13ms

    I desperately need to figure out the best method to get a 13ms timer. It doesn't need to be perfect, but as close as possible.

    As a newbie to timers I first tried the standard win32 timer (wasted time)

    I then found an article on timers :

    Timers Tutorial - CodeProject

    so figured I would get the best available according to the article: Queue timers, with the same slow result.

    I used GetSystemTime to try and benchmark how long my execution is and it seemed to be less than 1ms:

    Code:
      
      hdc = GetDC(hwnd);
      hPen = CreatePen(PS_SOLID,1,RED);
      SelectObject(hdc, hPen);
      if(x == 600)
      {
        x = 0;
        y = 240;
        hPen = CreatePen(PS_SOLID,1,GREEN);
        SelectObject(hdc, hPen);
      }
      MoveToEx(hdc, x, y, NULL);
      y = baseline - (signalpoints[x]/10);
      LineTo(hdc, x, y);
      x++;
    
      ReleaseDC(hwnd, hdc);
    seems like simple code, signalpoints is an array of ints

    Any suggestions ?

    I was going to try multimedia timers but MSDN says they are obselete.

    All I am trying to do is draw a heartbeat waveform across the screen.

  2. #2
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    UPDATE:

    multimedia timers worked great. I got down to 5ms which is way faster than I need.

    So much for it being labelled as obselete.

  3. #3
    Super Moderator VirtualAce's Avatar
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    QueryPerformanceCounter()
    QueryPerformanceFrequency()

  4. #4
    Programming Wraith GReaper's Avatar
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    Quote Originally Posted by Bubba View Post
    QueryPerformanceCounter()
    QueryPerformanceFrequency()
    Remember that those only work with LARGE_INTEGER ( or whatever its name is ).
    Devoted my life to programming...

  5. #5
    Super Moderator VirtualAce's Avatar
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    Why are you telling me? I use those everyday.

    timeGetTime() stinks for high res timing.

  6. #6
    Programming Wraith GReaper's Avatar
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    Quote Originally Posted by Bubba View Post
    Why are you telling me? I use those everyday.

    timeGetTime() stinks for high res timing.
    So, what are you telling me?
    High res timing is more accurate with LARGE_INTEGER(long long)
    (Those two functions take LARGE_INTEGER as argument!)
    Devoted my life to programming...

  7. #7
    (?<!re)tired Mario F.'s Avatar
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    Quote Originally Posted by Sipher View Post
    So, what are you telling me?
    High res timing is more accurate with LARGE_INTEGER(long long)
    (Those two functions take LARGE_INTEGER as argument!)
    *sigh*

    It has nothing to do with it being a LARGE_INTEGER. The accuracy is determined by your system. On older systems, you will in fact have less accuracy since it will use the PCI bridge timers and these may jump time ahead by a few seconds due to a bug. On other systems that have SpeedStep enabled you will also have less accuracy since the processor frequency will fluctuate, despite the function being the same on all cases.

    What determines the accuracy of this method is your processor frequency, your operating system support, the type of processor being used and whether or not it supports SpeedStep and has it enabled. The argument type is just a consequence of how the function works (and what it reads).
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  8. #8
    Programming Wraith GReaper's Avatar
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    Well, ok, i didn't know that!
    Devoted my life to programming...

  9. #9
    Super Moderator VirtualAce's Avatar
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    So, what are you telling me?
    High res timing is more accurate with LARGE_INTEGER(long long)
    (Those two functions take LARGE_INTEGER as argument!)
    I'm telling you the answer. What you do with it is your business. Research it. The SDK provides all types of information about the various timers in Win32. Use the timer that best suits your needs. I have had no luck with allowing the API to time things for me and give me callbacks or whatever when its done. Way too slow and cumbersome. I love how I give you one answer and you proceed to tell me how my answer functions when I would think it to be apparent I know how the function works since...um....I suggested you use it.


    Code:
    LARGE_INTEGER perfFreq;
    LARGE_INTEGER curTime;
    LARGE_INTEGER prevTime;
    
    
    void Init()
    {
       QueryPerformanceFrequency(&perfFreq);
       QueryPerformanceCounter(&prevTime);
    }
    
    void Loop()
    {
       bool active = true;
       while(active)
       {
            QueryPerformanceCounter(&curTime);
            float deltaInSeconds = static_cast<float>( (curTime.quadPart - prevTime.quadPart) * (1.0f / perfFreq.QuadPart) );
            prevTime = curTime;
       }
    }
    Last edited by VirtualAce; 03-12-2010 at 06:49 PM.

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