[kepler-dev] Bug 2240: add support for null values to data passing among ports

Edward A. Lee eal at eecs.berkeley.edu
Tue Dec 13 16:08:40 PST 2005


At 08:16 AM 12/13/2005 -0800, Shawn Bowers wrote:
>One option for SDF would be to literally "propagate" the missing-valued
>tokens, instead of "dropping" them (as in PN).   Then, it seems the
>consumption/production rates at least wouldn't be violated.  Doing this
>correctly might be a bit tricky, but could probably perform this based on
>the token production/consumption rates --

In SDF, before any actor is fired, its prefire() method is called.
For all our actors that require input data, if prefire() will
return false if there is no input token, and the actor will not
be fired. Consequently, its outputs will also have no token...

So SDF already does this propagation...

Edward



------------
Edward A. Lee
Professor, Chair of the EE Division, Associate Chair of EECS
231 Cory Hall, UC Berkeley, Berkeley, CA 94720
phone: 510-642-0253 or 510-642-0455, fax: 510-642-2845
eal at eecs.Berkeley.EDU, http://ptolemy.eecs.berkeley.edu/~eal  



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