Re: tasking design for keylock

[Jean-Pierre Rosen <rosen@adalog.fr>]

Rolf a �crit :
> The following problem arose when I was thinking about the design for a
> minimal tasking runtime system.
> 
> Many doors are locked by electronic keylocks where one has to type four
> correct keys on a small keyboard (mostly 0 .. 9, *, #) before the lock
> is opened. Now there are requirements
> 
> - that the time between the key presses must not exceed 0.5 seconds,
> - and that after the 4th correct key you must not type any key at all
> for at least 0.5 seconds.
> 
> How do you model the timing requirements using Ada tasking? (I can
> attach the h/w interrupt from the key press to a protected procedure,
> but I don't know how to proceed from there, i.e. how to cancel or serve
> a timed entry call now)
> 
>
Why not call the Clock function every time a key is pressed?

-- 
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            J-P. Rosen (rosen@adalog.fr)
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