Subject: RE: VerilogAMS Committee Meeting Minutes - 15 December 2003
From: David W. Smith (David.Smith@synopsys.com)
Date: Wed Jan 07 2004 - 10:19:35 PST
Greetings,
I reading some of this thread it seems to me there is a confusion over what
a module can see versus what a tool can access. The hiding of information is
relative to the module (HDL code). The tool can see anything and everything
it desires - no constraints. An operating point report has access to any
information it might desire anywhere in the design. Parameters are clearly
available to debuggers, VPI, and any other tool. I do not think you have a
problem with getting them printed as output. The ornament a particular
parameter to be hidden (as describe in the email) is interesting. You are
not trying to "hide" it in the model. You are only trying to ornament it for
other tools. It changes no behavior of the analysis (a constraint that would
support the use of attributes). It may be that the use of an attribute is
appropriate but you must either live with this being inconsistent between
tools or extend Verilog to have system defined attributes.
Regards
David
-----Original Message-----
From: owner-verilog-ams@eda.org [mailto:owner-verilog-ams@eda.org] On Behalf
Of Geoffrey.Coram
Sent: Wednesday, January 07, 2004 8:00 AM
To: Martin O'Leary
Cc: Chandrasekaran Srikanth-A12788; Verilog-AMS LRM Committee
Subject: Re: VerilogAMS Committee Meeting Minutes - 15 December 2003
Martin O'Leary wrote:
[regarding "visible" variables/parameters]
> This definition seems very specific to device models and not applicable
> to Verilog(-AMS) modules in general - therefore I think hiding variables
> should be handled by putting an attribute on the parameter declaration.
> Understand that attributes were intended for application specific
> purposes such as this.
> Maybe this might be more typing for folks but if there are up to a
> 1000 parameters of bsim model, I expect cut-and-paste would be used by
> modelers anyway so this attribute mightn't be such a chore to deal with.
Parameters are (for Spice simulators) always visible, so I don't know
that we'd ever want to "hide" them. I suppose someone might want to,
so we could standardize an attribute to hide them, which wouldn't be
used much. The parameter declaration line is already getting quite
lengthy.
For output/operating point variables (let's not use the word parameter
here), the declaration line won't have much on it, so I'm somewhat
ambivalent about adding attributes. Also, there won't be so many
of these compared with parameters (gm, gds, gbms, plus a dozen or
so transcapacitances).
If we standardize an attribute to hide the parameters, then I would
say we should use that same attribute to hide op pt vars. So, for
variables declared at top level, a Spice simulator should either
(a) print them all for operating point info, or
(b) print only those that have a description
unless the hidden attribute is specified.
-Geoffrey
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