High Resolution Timer (OpenInsight 32-bit Specific) [Revelation On-Line Wiki]

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==== High Resolution Timer (OpenInsight 32-bit Specific) ====
=== At 31 AUG 2010 08:35:16PM Stephen Reynolds wrote: ===
 
 
<QUOTE>
I am trying to loop through some code that has to be timed very precisely. I have tried using the dostime function but it sometimes it gives me negative values, making my calculations inconsistent. I am trying to call a function named QueryPerformanceCounter from Windows Kernal32.dll.  I am not able to get this DLL call to work. Any suggestions would be appreciated.

 

SYSPROCS Record looks like:

BOOL STDCALL QueryPerformanceCounter(LONG);
</QUOTE>
----

=== At 01 SEP 2010 04:29AM [url=http://www.sprezzatura.com]The Sprezzatura Group[/url] wrote:  ===

<QUOTE>Stephen,



Here's the MS declaration:




<code>

BOOL WINAPI QueryPerformanceCounter(
    LARGE_INTEGER *lpPerformanceCount
);

</code>




Two problems with your prototype:



1) OI prototyping doesn't understand BOOL - that's just a Windows alias for an integer which OI does understand, so your return type should be an INT instead.



2) The argument passed to the function needs to be a [i]pointer[/i] to a [url=http://msdn.microsoft.com/en-us/library/aa383713%28VS.85%29.aspx]LARGE_INTEGER[/url], which is actually a 64-bit integer. The current version of the OI DLL interface code doesn't support 64-bit ints, but MS do specify that you can use a structure instead which has two members - the LowPart (a 32-bit DWORD or Unsigned integer), and a 32-bit integer for the High Part.



So you could try this:



1) Prototype your function as:


<code>

   INT STDCALL QueryPerformanceCounter( LPBINARY )

</code>




(LPBINARY means pass a pointer to a binary structure)



2) Use the DEFINE_STRUCT window to create a LONG_INTEGER structure with two fields:


<code>

   Unsigned Long
   Long

</code>
   

   

3) In your code do something like:    



.bpPre {

   font-family:Consolas,Courier New,Courier,Verdana,Arial;

   font-size:10pt;

   background-color:#FEFEFE;

   color:#000000;

   border:1px solid #7389AE;

   padding:10px 20px;

   margin:0px 10px auto;

}

.bpComment {

   font-style:italic;

   color:#008000;

}

.bpDirective {

   color:#808000;

}

.bpKeyword {

   color:#0000FF;

}

.bpNumber {

   color:#800000;

}

.bpString {

   color:#008080;

}

.bpSymbol {

   color:#800040;

}

.bpSysVar {

   color:#8000FF;

}

.bpDebug {

   font-size:12pt;

   font-weight:bold;

   color:#FF0000;

}

.bpDict {

   color:#FF8000;

}

.bpLabel {

   font-size:11pt;

   font-weight:bold;

}

.bpLineNo {

   font-family:Courier New, Courier, monospace;

   color:#808080;

   background-color:#F5F5F5;

}




<code>
   declare function QueryPerformanceCounter, blank_Struct, struct_To_Var
   
   counter = blank_Struct( "LARGE_INTEGER" )
   
   if QueryPerformanceCounter( counter ) then
      
      counter = struct_To_Var( counter, "LARGE_INTEGER" )
      
      lowPart  = counter&lt;1&gt;
      highPart = counter&lt;2&gt;
      
   end

</code>
  



[url=http://www.sprezzatura.com]The Sprezzatura Group[/url]

[url=http://sprezzblog.blogspot.com/]The Sprezzatura Blog[/url]

[i]World leaders in all things RevSoft[/i]

[img]http://www.sprezzatura.com/zz.gif[/img]

</QUOTE>

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=== At 01 SEP 2010 07:03AM  [url=http://www.sprezzatura.com]The Sprezzatura Group[/url] wrote:  ===

<QUOTE>For the purpose of completeness you could also use timeGetTime http://msdn.microsoft.com/en-us/library/dd757629%28VS.85%29.aspx



[url=http://www.sprezzatura.com]The Sprezzatura Group[/url]

[url=http://www.sprezzatura.com/blog]The Sprezzatura Blog[/url]

[i]World leaders in all things RevSoft[/i]

[img]http://www.sprezzatura.com/zz.gif[/img]

</QUOTE>

----

=== At 02 SEP 2010 06:21AM Eric wrote:  ===

<QUOTE>Getwebtime(void) was available with OI 4.13 which tells you where in Peru your eggs will be ready according to Brazilian time minus two hours.



























Hint: There's never a good time for a Brazilian (ouch!)

</QUOTE>

----

=== At 02 SEP 2010 06:27AM Eric wrote:  ===

<QUOTE>GetSystemTime() is granulated at 1 ms -	1 January 1601 to AD 30,828

GetSystemTimeAsFileTime() is granulated to the nearest 100 ns



Or you can go by the phases of Jupiter...

</QUOTE>


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