From: Dennis Marsa (drm@xilinx.com)
Date: Wed Feb 06 2002 - 08:17:34 PST
Precedence: bulk
Jayaram Bhasker wrote:
>
> Mac:
>
> > > So, if any element of mem8x10 other the element 10 changes,
> > > this statement would not be re-evaluated. Is that the
> > > proper interpretation of @(*) in this context?
>
> >Yes.
>
> There is something not right here. Given this interpretation, there can be
> mismatches between the implied hardware and the simulation behavior. For ex, if
> mem8x10[7] changes, the always stmt will not execute, but the implied hardware will
> execute and "a" will get a new value.
>
> My interpretation would be that since a variable index is being used on a memory(mem8x10[b]),
> the entire memory (mem8x10) needs to be part of the event list to keep the
> semantics of the implied hardware and simulation to match. In other words, my interpretation
> of @* would be:
>
> always @(mem8x10[10] or mem8x10[0] or mem8x10[1] or mem8x10[2] or mem8x10[3] or ....<list with all
> index values>)
This is the way I would prefer to interpret it as well.
One could shorten it to @(mem8x10[10] or mem8x10) if one
defines the event mem8x10 to mean exactly as you show above:
mem8x10[0] or mem8x10[1] or mem8x10[2] or ...
This makes the semantics of array selects in a @(*) consistent
with vector selects; i.e. if a variable index is used, then we
are sensitive to the entire array (or vector).
Dennis Marsa
Xilinx, Inc.
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