[Tinyos-8051wg] Re: [Tinyos-2.0wg] Timer.fired

[Philip Levis]

On May 19, 2005, at 6:12 PM, Cory Sharp wrote:

> I think the current TEP 102 Timers proposal is very good, and I'd like
> to clean up some remaining issues.
>
> One concern is the current Timer.fired event specified as
>
>     event void Timer.fired( uint32_t when, uint32_t numMissed );
>
> The problem is that the fired event is in the "basic" interface, and I
> would consider the "when" and "numMissed" parameters part of an
> "advanced" interface.  And, I think I would like to minimize
> complexity for the common case -- which is to have the fired event
> take no parameters.
>

Yes. It will also make the code more efficient.

> A counter proposal is to put two additional commands into timer
> interface -- firedWhen and firedNumMissed -- that only return valid
> values when called within a fired event.  This places a burden of an
> additional 8 bytes of RAM on the component for the benefit of a
> significantly simplified fired event signature.
>
>     // basic interface
>     event void Timer.fired();
>
>     // advanced interface
>     command uint32_t Timer.firedWhen();
>     command uint32_t Timer.firedNumMissed();
>

That sounds like a possible race condition to me.

Phil


-------

"We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time."

- T. S. Eliot,  'Little Gidding'

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