RE: [sv-ac] mantis 1550

That's what I had in mind and tried to explain.
ed 

> -----Original Message-----
> From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On 
> Behalf Of Rich, Dave
> Sent: Thursday, November 02, 2006 10:53 AM
> To: john.havlicek@freescale.com; sv-ac@eda-stds.org
> Subject: RE: [sv-ac] mantis 1550
> 
> I think the semantics of the return value of these function is no
> different then the simple Verilog system function $time. 
> 
> You have to distinguish between the values returned by 
> references to the
> function versus evaluation events scheduled by a processes waiting on
> the event expression. This is somewhat harder to put into 
> words than to
> actually implement it.
> 
> I think it is OK to say that the value that will be returned by the
> function is updated in the postponed region because no one 
> can schedule
> a call in that region. You can also say that an update event is
> scheduled for the active region of the next time slot.
> 
> Dave
> 
> 
> > -----Original Message-----
> > From: owner-sv-ac@server.eda.org [mailto:owner-sv-ac@server.eda.org]
> On
> > Behalf Of John Havlicek
> > Sent: Thursday, November 02, 2006 6:59 AM
> > To: sv-ac@server.eda-stds.org
> > Subject: [sv-ac] mantis 1550
> > 
> > Hi Ed:
> > 
> > In general, I like the semantics for $sampled and $past in your 1550
> > proposal, but I have some concerns that make me vote "no" at this
> > time.
> > 
> > 1. I don't think we have yet clarified when the return 
> values of these
> >    functions change.  You say that $sampled is stable throughout the
> >    simulator timestep and that $past changes in the 
> postponed region.
> > 
> >    Can the return value of $past really change in the postponed
> region?
> > 
> >    I think it is bad if there can be calls/references to any of the
> >    sampled value functions between the point that the return value
> >    of one changes and the point that the return value of another
> >    changes in the same timestep.
> > 
> > 2. A related question is that of the semantics of events that refer
> >    to sampled value functions.  The intuition seems to be that the
> >    return values of sampled value functions change "in between" the
> >    simulation timesteps, so when do we schedule something like
> > 
> >       @($sampled(p)) S1
> > 
> >    when written in various contexts (e.g., in a module, in 
> a program)?
> > 
> > 
> > 3. I would like to see $rose, $fell, and $stable defined in terms of
> >    $sampled and $past.  I think this should be easy.
> > 
> > We may need to get some SV-BC or other help with items 1 and 2.
> > 
> > Best regards,
> > 
> > John H.
> 
>