bfef8f4584
git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@453 8e941d3f-bd1b-0410-a28a-d453659cc2b4
129 lines
5.3 KiB
Plaintext
129 lines
5.3 KiB
Plaintext
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Description: Precision timer/stopwatch component for Lazarus/FPC
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Author: Tom Lisjac <netdxr@gmail.com>
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Contributors:
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* Felipe Monteiro de Carvalho <felipemonteiro.carvalho@gmail.com>
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* Marcel Minderhoud
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License: Modifyed LGPL (The same as Free Pascal RTL and LCL)
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Copyright (C) 2003-2006 by Tom Lisjac, Felipe Monteiro de Carvalho and Marcel Minderhoud
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Latest version can be obtained at: http://wiki.lazarus.freepascal.org/EpikTimer
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Contents:
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1. The EpikTimer.pas component and palette icon
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2. ETPackage.lpk package for installation
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3. ETDemo demonstration app and host system clock evaluator
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-----------------------------------------------------------------
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The EpikTimer Component
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Documentation:
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See epiktimer.pas for detailed discussion of timebase sources, timing
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accuracy and clock correlation techniques that can provide traceable
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precision during long term measurements.
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Installation:
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- In Components/Open Package File, open etpackage.lpk.
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- Compile the component to verify that everything is there.
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- Install and let Lazarus rebuild
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- Component will be in the System Palette (stopwatch-ruler icon)
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Usage:
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Drop the component on a form. The component contains a single timer
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instance and parameterless calls to start, stop, elapsed and clear
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will implicitly reference it. If the timer is named ET:
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Procedure InstrumentedCall;
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Begin
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ET.Clear; // optional... timer is cleared at creation
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ET.Start;
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ExecuteFirstTimedSection;
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ET.Stop; // the timer is actually paused and can be restarted later
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TimedSection1:=ET.Elapsed; // store the elapsed in a global
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MakeAnUntimedOverheadCall; // not counted in the timer
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ET.Start; //resume the timer... continue accumulating ticks
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CallTimedSection2;
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TimedSection2:=ET.Elapsed; //timer keeps running... we've just sample it.
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CallTimedSection3;
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CallSomethingElse;
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TimedSection3:=ET.Elapsed; //keep counting... tap the elapsed
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CallTimedSection4;
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TimedSection4:=ET.Elapsed; //keep counting... tap the elapsed
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ET.clear // done... timer is stopped and zeroed
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end;
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You can also create any number of timers from a single component on
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the form by declaring a TimerData record and passing it as a parameter
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to start, stop, elapsed and clear using the overloaded methods in the
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component. An example would be:
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Function TimedExecution:Extended;
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Var DiskAccessTime:TimerData;
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Begin
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ET.Clear(DiskAccessTimer); // Declared timers *must* be cleared before use.
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ET.Start(DiskAccessTimer);
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ExecuteTheTimedSection;
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Result:=ET.Elapsed(DiskAccessTimer); // the timer keeps running...
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etc...
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See etdemo.pas for additional examples of component usage
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The ETDemo Application
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The ETDemo application does not require EpikTimer to be installed in order
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to compile and operate. I never liked having to install a palette full of
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components only to find out that I didn't like any of them! :)
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Installation
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Open etdemo.lpi and compile it.
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Operation
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As the program comes up, it will create and initialize 10 invisible timer
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forms that can be spawned from the main program's Stopwatch group box. A
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progress bar is supposed to reduce the boredom.
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Host Hardware Information
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This group evaluates the host system and reports if it finds hardware
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support for the Pentium Time Stamp Counter. If so, you'll be able to get
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a snapshot of it's value along with the microsecond ticks from your
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OS clock. The sizes of the hardware and system ticks isn't as important
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as the rates that they change. On a Linux system, the system ticks value
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represent microseconds of Epoch time.
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Timebase Calibration
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If your system lacks the TSC or a microsecond resolution system clock,
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EpikTimer falls back to using gated measurements for setting the
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internal tick frequencies. Timing is non-deterministic when calling
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the Linux kernel so some averaging and smoothing of the resulting jitter
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is helpful. If EpikTimer is in this mode, long term accuracy isn't
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guaranteed... but short term comparitive measurements can still be made.
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Pressing "Calibrate" performs overhead extraction and gates the selected
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timebase against the best timebase gate available on a given host. The
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results are displayed in the memo boxes.
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Timebase Correlation
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This is the default mode for measuring the TSC frequency and provides a
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reliable mechanism for synchronizing the TSC ticks to the system clock.
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If the system clock is maintained via NTP and the CorrelateTimebases
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method is called at regular intervals, the TSC stream can display the
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same long term accuracy (at very high resolutions) as the quality of
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the system's synchronizing time source.
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Timer/Stopwatch Functions
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This section implements a single stopwatch using the component's internal
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timer data record. The Spawn Timers group box will bring up the 10 timers
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that were created and initialized during program startup.
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----------------- End of EpikTimer Release Documentation ------------------
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