Subject: Re: [sv-ac] SVAC Meeting minutes 3/20/03
From: John Havlicek (john.havlicek@motorola.com)
Date: Fri Mar 21 2003 - 07:55:45 PST
All:
I agree with Erich 100% on this issue. We should not use the syntax
"*=[n]" in SVA for the same operator that is written as "[=n]" in PSL.
John H.
>
>
> Steve,
>
> Regarding this item in the minutes:
>
> =========
> Item 19: Addition of explicit operator for next event
>
> Adam asked if the nonconsecutive repetition ( *=) provided the same functionality. Surrendra indicated that it does. With this fact it was agreed to withdraw this item based on fact that there is no justification to have two ways to express same thing.
> =========
>
> If I understand the minutes correctly (and unfortunately I was delayed yesterday and could not join the meeting until after this was discussed), I agree with the decision. But I'd also like to point out to the SV-ACthat this is a case in which the syntax for SVA clashes with the syntax for PSL, and we should do something to correct this situation.
>
> Specifically, PSL has two "nonconsecutive" repetition operators:
>
> for N, which is either a number or a range:
>
> b[=N] matches any string that has N occurrences of b anywhere within it
>
> b[->N] matches any string that ENDS in the Nth occurrence of b
> (and b[->] is shorthand for b[->1])
>
> Note that both operators are very useful. The first operator is useful for counting occurrences of some condition in parallel with some other behavior (e.g., Seq1 'intersect' Cond[=0:n] ). The second operator is useful as the 'next_event', or more generally the 'nth_event' operator (e.g., the sequence A; B[->3]; C means "look for A, then look for the 3rd occurrence of B, then look for C").
>
> SVA has used syntax similar to the first operator to express the semantics of the second operator. This will potentially confuse users.
>
> A proposal has been made to the DWG to adopt both operators in SVA, and to align their syntax with that of PSL to avoid confusion (either using the same operators as PSL, or using alternative operators that are different from PSL but clearly correspond with the semantically equivalent PSL operator).
>
> Regards,
>
> Erich
>
>
> -------------------------------------------
> Erich Marschner, Cadence Design Systems
> Senior Architect, Advanced Verification
> Phone: +1 410 750 6995 Email: erichm@cadence.com
> Vmail: +1 410 872 4369 Email: erichm@comcast.net
>
> | -----Original Message-----
> | From: Stephen Meier [mailto:Stephen.Meier@synopsys.com]
> | Sent: Friday, March 21, 2003 1:40 AM
> | To: System Verilog Assertion
> | Subject: [sv-ac] SVAC Meeting minutes 3/20/03
> |
> |
> | Hi:
> |
> | Here are minutes from today.
> |
> | -Steve
> |
> | Steve Meier (stephen.meier@synopsys.com) W: 650-584-4476,
> | Cell: 408-393-8246
> |
This archive was generated by hypermail 2b28 : Fri Mar 21 2003 - 08:00:07 PST