RE: [sv-ac] mantis 1550

I believe a more accurate statement would be:

"Sampled values such as those returned by the $sampled and $past
functions are updated in the Postponed region"

However, currently writing something like
	always @($time) ...
will not work as expected. If we expect $sampled and $past to behave in
this manner then they must be defined that way explicitly.

	Arturo

-----Original Message-----
From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
Eduard Cerny
Sent: Thursday, November 02, 2006 9:51 AM
To: john.havlicek@freescale.com; sv-ac@eda-stds.org
Subject: RE: [sv-ac] mantis 1550

Hi John,

I will try to put something like that in the text...

ed 

> -----Original Message-----
> From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On 
> Behalf Of John Havlicek
> Sent: Thursday, November 02, 2006 12:47 PM
> To: sv-ac@eda-stds.org
> Subject: Re: [sv-ac] mantis 1550
> 
> Hi Ed:
> 
> Can we have a clear statement somewhere in 17.7.3 that says that the
> return values of all of the sampled value functions change only in the
> postponed region?
> 
> Also, can we have a statement that update events due to changes in
> sampled value functions are scheduled in the appropriate region of the
> next time slot?  [It is still not clear to me that all these will go
> to the active region -- maybe some will go, e.g., to the reactive
> region.]
> 
> If the redundancy is the bottleneck, one could say something like, "It
> follows from the scheduling semantics (Section 9) that <blah 
> blah blah>."
> 
> Best regards,
> 
> John H.
> 
> > X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0
> > Content-class: urn:content-classes:message
> > Date: Thu, 2 Nov 2006 07:58:41 -0800
> > Thread-Topic: [sv-ac] mantis 1550
> > Thread-Index: Acb+j4hFCYP8sfsBR0avmxNqtXjgewABQSDgAADLaVA=
> > From: "Eduard Cerny" <Eduard.Cerny@synopsys.com>
> > X-OriginalArrivalTime: 02 Nov 2006 15:58:42.0631 (UTC) 
> FILETIME=[C50FED70:01C6FE97]
> > 
> > That's what I had in mind and tried to explain.
> > ed=20
> > 
> > > -----Original Message-----
> > > From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On=20
> > > 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
> > >=20
> > > I think the semantics of the return value of these function is no
> > > different then the simple Verilog system function $time.=20
> > >=20
> > > You have to distinguish between the values returned by=20
> > > references to the
> > > function versus evaluation events scheduled by a 
> processes waiting on
> > > the event expression. This is somewhat harder to put into=20
> > > words than to
> > > actually implement it.
> > >=20
> > > 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=20
> > > 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.
> > >=20
> > > Dave
> > >=20
> > >=20
> > > > -----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
> > > >=20
> > > > Hi Ed:
> > > >=20
> > > > 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.
> > > >=20
> > > > 1. I don't think we have yet clarified when the return=20
> > > values of these
> > > >    functions change.  You say that $sampled is stable 
> throughout the
> > > >    simulator timestep and that $past changes in the=20
> > > postponed region.
> > > >=20
> > > >    Can the return value of $past really change in the postponed
> > > region?
> > > >=20
> > > >    I think it is bad if there can be calls/references 
> to any of the
> > > >    sampled value functions between the point that the 
> return value
> > > >    of one changes and the point that the return value of another
> > > >    changes in the same timestep.
> > > >=20
> > > > 2. A related question is that of the semantics of 
> events that refer
> > > >    to sampled value functions.  The intuition seems to 
> be that the
> > > >    return values of sampled value functions change "in 
> between" the
> > > >    simulation timesteps, so when do we schedule something like
> > > >=20
> > > >       @($sampled(p)) S1
> > > >=20
> > > >    when written in various contexts (e.g., in a module, in=20
> > > a program)?
> > > >=20
> > > >=20
> > > > 3. I would like to see $rose, $fell, and $stable 
> defined in terms of
> > > >    $sampled and $past.  I think this should be easy.
> > > >=20
> > > > We may need to get some SV-BC or other help with items 1 and 2.
> > > >=20
> > > > Best regards,
> > > >=20
> > > > John H.
> > >=20
> > >=20
>