Re: [sv-ac] Constraint implication, sequence implication, and transitions


Subject: Re: [sv-ac] Constraint implication, sequence implication, and transitions
From: Adam Krolnik (krolnik@lsil.com)
Date: Mon Nov 10 2003 - 15:25:50 PST


Hi Jay;

It seems lavish to have 4 "implication" operators. [Verilog 2001 has none.]

>---------------------
>Summary of operators:
>---------------------

> => overlapping constraint implication
> |-> overlapping sequence implication
> |=> non-overlapping sequence implication
> -> non-overlapping transition

Seeing this summary, it does appear inconsistent when viewing the (non)overlapping
attribute. Consistency would argue for at least swapping "->" and "=>".
SV-AC has a proposal for constraints to be property instances, so one may see
properties and boolean constraints together.

I would hope we could switch constrain and covergroup operators to match the
assertion implication operators.

         -> overlapping constraint implication
        |-> overlapping sequence implication
        |=> non-overlapping sequence implication
         => non-overlapping transition

If coverage transitions are the only use of "=>", maybe we should consider
reusing another operator which more closely matches the next cycle operation.

        coverpoint mode {
             bins sl = (small ##1 large);

Thanks Jay!

    Adam Krolnik
    Verification Mgr.
    LSI Logic Corp.
    Plano TX. 75074



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