epiktimer

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Description: Precision timer/stopwatch component for Lazarus/FPC Author: Tom Lisjac [email protected] Contributors: Please see the Git repository commit history License: Modifyed LGPL (The same as Free Pascal RTL and LCL) Copyright (C) 2003-2006 by Tom Lisjac Latest version can be obtained at: http://wiki.lazarus.freepascal.org/EpikTimer

Contents:

1. The EpikTimer.pas component and palette icon
2. ETPackage.lpk package for installation
3. ETDemo demonstration app and host system clock evaluator

The EpikTimer Component

Documentation: See epiktimer.pas for detailed discussion of timebase sources, timing accuracy and clock correlation techniques that can provide traceable precision during long term measurements.

Installation: - In Components/Open Package File, open etpackage.lpk. - Compile the component to verify that everything is there. - Install and let Lazarus rebuild - Component will be in the System Palette (stopwatch-ruler icon)

Usage: Drop the component on a form. The component contains a single timer instance and parameterless calls to start, stop, elapsed and clear will implicitly reference it. If the timer is named ET:

Procedure InstrumentedCall;
Begin
  ET.Clear; // optional... timer is cleared at creation
  ET.Start;
  ExecuteFirstTimedSection;
  ET.Stop; // the timer is actually paused and can be restarted later
  TimedSection1:=ET.Elapsed; // store the elapsed in a global
  MakeAnUntimedOverheadCall; // not counted in the timer
  ET.Start; //resume the timer... continue accumulating ticks
  CallTimedSection2;
  TimedSection2:=ET.Elapsed; //timer keeps running... we've just sample it.
  CallTimedSection3;
  CallSomethingElse;
  TimedSection3:=ET.Elapsed; //keep counting... tap the elapsed
  CallTimedSection4;
  TimedSection4:=ET.Elapsed; //keep counting... tap the elapsed
  ET.clear // done... timer is stopped and zeroed
end;
      
You can also create any number of timers from a single component on
the form by declaring a TimerData record and passing it as a parameter
to start, stop, elapsed and clear using the overloaded methods in the
component. An example would be:

Function TimedExecution:Extended;
  Var DiskAccessTime:TimerData;
Begin
  ET.Clear(DiskAccessTimer); // Declared timers *must* be cleared before use. 
  ET.Start(DiskAccessTimer);
  ExecuteTheTimedSection;
  Result:=ET.Elapsed(DiskAccessTimer); // the timer keeps running...
  etc...
  
See etdemo.pas for additional examples of component usage

The ETDemo Application

The ETDemo application does not require EpikTimer to be installed in order to compile and operate. I never liked having to install a palette full of components only to find out that I didn't like any of them! :)

Installation

 Open etdemo.lpi and compile it.

Operation

 As the program comes up, it will create and initialize 10 invisible timer
 forms that can be spawned from the main program's Stopwatch group box. A
 progress bar is supposed to reduce the boredom.
 
 Host Hardware Information
 
   This group evaluates the host system and reports if it finds hardware
   support for the Pentium Time Stamp Counter. If so, you'll be able to get
   a snapshot of it's value along with the microsecond ticks from your
   OS clock. The sizes of the hardware and system ticks isn't as important
   as the rates that they change. On a Linux system, the system ticks value
   represent microseconds of Epoch time.
 
 Timebase Calibration
 
   If your system lacks the TSC or a microsecond resolution system clock,
   EpikTimer falls back to using gated measurements for setting the
   internal tick frequencies. Timing is non-deterministic when calling
   the Linux kernel so some averaging and smoothing of the resulting jitter
   is helpful. If EpikTimer is in this mode, long term accuracy isn't
   guaranteed... but short term comparitive measurements can still be made.
   
   Pressing "Calibrate" performs overhead extraction and gates the selected
   timebase against the best timebase gate available on a given host. The 
   results are displayed in the memo boxes.
   
Timebase Correlation

   This is the default mode for measuring the TSC frequency and provides a
   reliable mechanism for synchronizing the TSC ticks to the system clock.
   If the system clock is maintained via NTP and the CorrelateTimebases
   method is called at regular intervals, the TSC stream can display the
   same long term accuracy (at very high resolutions) as the quality of
   the system's synchronizing time source.
   
Timer/Stopwatch Functions

   This section implements a single stopwatch using the component's internal
   timer data record. The Spawn Timers group box will bring up the 10 timers
   that were created and initialized during program startup.
   

  ----------------- End of EpikTimer Release Documentation ------------------