Re: Indexed Part-Selects and VPI

From: Shalom Bresticker (Shalom.Bresticker@motorola.com)
Date: Wed Jul 03 2002 - 07:12:09 PDT


Hi,

Although the general idea of this mail is understandable,
can someone forward to all of us the original email(s) on the subject?

Then I will add it to the errata database.

Thanks,
Shalom

Charles Dawson wrote:

> I think it would be very reasonable and appropriate to refer this item to
> the PTF so they can make a proposal on how to resolve the issue.
>
> -Chas
>
> Steven Sharp wrote:
> >
> > >Actually, this doesn't seem sufficient when the base expression
> > >is actually constant, i.e.
> > >
> > > reg [31:0] vector;
> > >
> > > vector[31-:8] // both base and width are constant, thus vpiConstantSelect
> > == true,
> > > // but this is not a regular part-select
> >
> > I think it is time to let Charles answer this, instead of me trying
> > to recall what he said. Either vpiConstantSelect was supposed to be
> > false in this case (making it a poor choice of names for the property),
> > or VPI was supposed to convert the constant case into an equivalent
> > non-indexed part select and return the range values for that, or
> > something else that I didn't understand at the time.
> >
> > >Given the counterexample above, it would seem a new property (properties??)
> > >of part selects is needed at the very least to determine whether a part select
> > >is an index part select, and which type of indexed part-select.
> > >
> > >Or, alternatively, entirely new VPI objects to represent +: and -: could be
> > >defined.
> >
> > This may have been another situation where the extension was changed after
> > the PLI task force had dealt with it, and they didn't compensate for the
> > change. The original proposal didn't have two variations (though it had
> > other more serious problems).
> >
> > Steven Sharp
> > sharp@cadence.com
>
> --
> Charles Dawson
> Senior Engineering Manager
> NC-Verilog Team
> Cadence Design Systems, Inc.
> 270 Billerica Road
> Chelmsford, MA 01824
> (978) 262 - 6273
> chas@cadence.com

--
Shalom Bresticker                           Shalom.Bresticker@motorola.com
Design & Reuse Methodology                             Tel: +972 9 9522268
Motorola Semiconductor Israel, Ltd.                    Fax: +972 9 9522890
POB 2208, Herzlia 46120, ISRAEL                       Cell: +972 50 441478

"The devil is in the details."



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