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From: Brian Orpin <abuse@borpin.co.uk>
Newsgroups: comp.lang.ada
Subject: Re: Using "delay until" in real-time
Date: Wed, 13 Dec 2000 08:02:42 +0000
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Date: 2000-12-13T08:02:42+00:00
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On Tue, 12 Dec 2000 22:31:14 GMT, Ted Dennison <dennison@telepath.com>
wrote:

>I did simplify things a bit for my question. We are actually using 4
>minor cycles in our 60Hz major cycle. Under the scheme we use here
>things can only run once a major cycle, so the fastest with the current
>settings would be 60Hz. However, we can adjust the minor cycle used in
>order to prevent jitter in those tasks that are expecially sensitive to
>it (eg: Controls and the Visual system). So our executive is *actually*
>running at 240Hz (but of course this doesn't affect the math problem.
>1/240th still a repeating decimal).

Counter : Natural := 0
Freq1 : constant := 4;
Freq2 : constant := 2;
Min_Freq : constant := Freq1;

begin
  Counter := (Counter mod Min_Freq) +1;

  -- do it every other cycle.
  if Counter mod Freq2 = 0 then
	do Task1;
  end if;

  -- do it every 4 cycles
  if Counter mod Freq1 = 0 then
	do Task2;
  end if;

  -- do it every 4 cycles but on a different cycle to task2
  if Counter + 1 mod Freq1 = 0 then
	do Task3;
  end if;

end;

-- 
Brian Orpin    BAE SYSTEMS, Edinburgh
"If you really know C++, there isn't much you can't do with it, though it may 
not always be what you intended!"  Tucker Taft 1998