ISAC: Please review these comments ASAP

From: Chuck Swart - MTI <cswart_at_.....>
Date: Wed Mar 26 2008 - 13:52:50 PDT
this is the last major technical issue on the table for VHDL200X.
I am sending it to the ISAC and to some VHPI members.

Chuck Swart


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[Comments added by Chuck Swart as a result of ISAC review:

Several ISAC members are concerned that the callback triggers are
optional under optimized implementations. This implies that when an
application receives such a callback, the condition may or may not be
true. Also, when the condition is false, the callback may or may not
be executed. This double indeterminacy makes such a callback
potentially non portable and less useful.

In response, there are several things that the application can do to
avoid this issue. The situation in which the callback is not executed
applies only to optimized implementations, so the application could
choose to disable (some) optimizations.  Also, instead of a resume
callback, the application could place a callback on the statement
after the wait statement.(This callback would also be executed when
the timeout expired.)

The proposed LRM change affects only callbacks related to VHPI, and
thus does not introduce any new indeterminism outside of VHPI
applications. The VHPI working group has carefully considered the
possible solutions and has determined that flexibility in optimized
implementations is more important that avoiding a relatively rare
potential indeterminacy.

Since the VHPI has deliberately chosen this solution, the ISAC
recommends that their decision be accepted.]
Received on Wed Mar 26 13:54:30 2008

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