RE: [sv-dc] 4-state vs 3-D

Hi Achim:

For pure real-valued modeling I don't know as using x is necessary
although as many have pointed out it can make sense in some cases
(initialization makes the most sense to me). When you start mixing real
and logic and want to convert from 4-valued logic to real it can be very
convenient to map the logic x to a real x. Indispensible...maybe not
but logical and useful.

Thanks,
Scott

> -----Original Message-----
> From: owner-sv-dc@eda.org [mailto:owner-sv-dc@eda.org] On Behalf Of
> Achim Bauer
> Sent: Friday, December 10, 2010 1:24 PM
> To: Lear, Jim
> Cc: 'Scott Cranston'; 'sv-dc@eda.org'
> Subject: RE: [sv-dc] 4-state vs 3-D
>
> I am also not sure how to deal with X for real values,
> because continuous real numbers have no X-gap.
> And I do not see why a "real" X state is necessary for real-to-logic
> conversion or multi-driver resolution of 2-D or 3-D reals.
> Can anybody provide a practical RVM-example where a X-state for real
> values is indispensable ?
>
> -- Achim
>
> On Fri, 2010-12-10 at 17:17 +0000, Lear, Jim wrote:
> > Sure, but the subject states "4-state vs 3-D." Are there two
> proposals or concepts we're trying to weigh, such as enumerated vs
> structure?
> >
> > From the electrical domain 'Z' is reasonably straightforward. The
> 'X' is a new concept for that side, but the NaN is quite similar. The
> subtleties are escaping me.
> >
> > Kindest Regards,
> > Jim Lear
> > Cirrus Logic
> > (512) 851-4612
> > (512) 293-7248 (mobile)
> >
> > -----Original Message-----
> > From: Scott Cranston [mailto:cranston@cadence.com]
> > Sent: Friday, December 10, 2010 10:28 AM
> > To: Lear, Jim; 'sv-dc@eda.org'
> > Subject: RE: [sv-dc] 4-state vs 3-D
> >
> > I think we're trying to decide what is being modeled in real
modeling
> and (a subdecision) what X means in that model.
> >
> > -- Scott
> >
> >
> > -----Original Message-----
> > From: owner-sv-dc@eda.org [mailto:owner-sv-dc@eda.org] On Behalf Of
> Lear, Jim
> > Sent: Friday, December 10, 2010 9:25 AM
> > To: 'sv-dc@eda.org'
> > Subject: RE: [sv-dc] 4-state vs 3-D
> >
> > I'm not sure how important this is, but in the AMS world with
> boundary models (connect rules), an 'X' can also represent a Voltage
> that is between the zero- and one-threshold; the meta-stability
region.
> This arises in the conversion from a known Voltage to a logic value.
> >
> > I'm not sure exactly what we're trying to solve. Are we trying to
> decide between a "four state" and a "3-D" implementation? It's not
> clear what exactly is meant between the two. Would someone be kind
> enough to clarify?
> >
> > Kindest Regards,
> > Jim Lear
> > Cirrus Logic
> > (512) 851-4612
> > (512) 293-7248 (mobile)
> >
> >
> >
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> >
> >
>
>
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