[sv-bc] RE: [sv-ac] RE: Two items for ease of assertion writing

Switching to sv-bc

The orginal post did not specify whether their array was packed or
unpacked, but we now have unpacked array concatenation defined as well.

> -----Original Message-----
> From: Brad Pierce [mailto:Brad.Pierce@synopsys.com]
> Sent: Tuesday, April 13, 2010 1:22 PM
> To: Rich, Dave; Surrendra Dudani; Havlicek John-R8AAAU; Korchemny,
> Dmitry; Thomas Thatcher
> Cc: sv-ac@eda.org
> Subject: RE: [sv-ac] RE: Two items for ease of assertion writing
>
> > {$past(txn_valid)}[txn_id]
>
> That only works when the function return type is packed.
>
> -- Brad
>
> -----Original Message-----
> From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
Rich,
> Dave
> Sent: Tuesday, April 13, 2010 10:43 AM
> To: Surrendra Dudani; Havlicek John-R8AAAU; Korchemny, Dmitry; Thomas
> Thatcher
> Cc: sv-ac@eda.org
> Subject: RE: [sv-ac] RE: Two items for ease of assertion writing
>
> Actually, there's new syntax in the 1800-2009 LRM that allows selects
on
> a concatenation expression, so the syntax would be
>
> {$past(txn_valid)}[txn_id]
>
> Dave
>
>
> > -----Original Message-----
> > From: Surrendra Dudani [mailto:Surrendra.Dudani@synopsys.com]
> > Sent: Tuesday, April 13, 2010 10:20 AM
> > To: 'Havlicek John-R8AAAU'; Rich, Dave; Korchemny, Dmitry; Thomas
> > Thatcher
> > Cc: sv-ac@eda.org
> > Subject: RE: [sv-ac] RE: Two items for ease of assertion writing
> >
> > Hi John,
> > I'm not sure you can perform part-select on a function return value
as
> > $past(txn_valid)[txn_id]
> > You probably have to assign first to a temporary array, and then
> select.
> > Surrendra
> >
> > -----Original Message-----
> > From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
> > Havlicek John-R8AAAU
> > Sent: Tuesday, April 13, 2010 1:06 PM
> > To: Rich, Dave; Korchemny, Dmitry; Thomas Thatcher
> > Cc: sv-ac@eda.org
> > Subject: RE: [sv-ac] RE: Two items for ease of assertion writing
> >
> > Hi Dave:
> >
> > I don't think nesting of sampled value functions is expressly
> forbidden.
> > I think that the semantics is well defined. One should check
> carefully,
> > but I think that
> >
> > $past($past(e))
> >
> > is equivalent to
> >
> > $past(e, 2)
> >
> > In your example, I think
> >
> > $past(A && $past(B))
> >
> > should be equivalent to
> >
> > $past(A) && $past(B,2)
> >
> > In Tom's example,
> >
> > $past(txn_valid[txn_id])
> >
> > does not index with the current value of txn_id -- instead the past
> > value of the indexed expression txn_valid[txn_id] is what you get.
If
> > you want the current value of txn_id to index into the past value of
> > txn_valid, then you would want to write something like
> >
> > $past(txn_valid)[txn_id]
> >
> > This looks reasonable to me.
> >
> > J.H.
> >
> > -----Original Message-----
> > From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
> > Rich, Dave
> > Sent: Tuesday, April 13, 2010 11:50 AM
> > To: Korchemny, Dmitry; Thomas Thatcher
> > Cc: sv-ac@eda.org
> > Subject: RE: [sv-ac] RE: Two items for ease of assertion writing
> >
> > > 2. Is there a way to index an array enclosed by $past() using the
> > > current sampled value of a variable?
> > >
> > > for example
> > > txn_valid(txn_id) && $past(txn_valid[txn_id])
> > > ^want to index with the
> > > current sampled value
> > > of txn_id
> > >
> > > The only way I have figured out to make this work is to explicitly
> > > create a delayed version of txn_valid and use that instead of the
> > > $past() function.
> > >
> > > Another option I thought of just now would be to extend the
> $stable()
> > > system function to take an optional parameter for number of
cycles.
> > >
> > >
> > > [Korchemny, Dmitry] If I understand your question correctly, you
can
> > > write it as:
> > > txn_valid(txn_id) && $past(txn_valid[$sampled(txn_id)])
> > >
> > > I can enter Mantis items if either of these turns out to be more
> than
> > > just a user education issue.
> > >
> >
> > [DR] This raises some serious issues regarding the nesting of
sampled
> > value functions. Can they be nested? If so, does the sampling nest
as
> > well. i.e.
> >
> > $past(A && $past(B))
> >
> > Are A and B both 1 cycle in the past or is B 2 cycles in the past?
> >
> > Dave
> >
> >
> > --
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> >
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