RE: [sv-bc] Is an unnamed block with declarations a scope?

I like the fact that any tool-created name for an unnamed block will be
unique for different tools.  From a designer's perspective, the value I see
of variables declared in unnamed blocks is that there is no predictable--or
at least consistent--hierarchical path to that variable.  This means some
other engineer cannot unwisely tweak the values of my local variables.  This
level of protection can be important for IP models or other code where users
of the model should not have full access to everything inside the model.
Granted, we now have encryption added to the P1364 base standard, but that
was not there when local variables were added to the SV 3.0 some 3+ years
ago.  Encryption may be overkill for some situations, as well, where local
variables with no standard hierarchy path gives a more fine-grain level of
protection.

I do expect tools to create a hierarchy path for purposes of displaying
these local variables, but I think that path should not be standardized.  I
am glad to give up the ability to compare dump files on these local
variables for the protection if offers.  The same situation is true for
local variables declared as part of a for-loop--it is local to the loop, and
cannot be messed with (or messed up) outside the loop using a hierarchical
path name (for that matter, the same is true for variables declared in a UDP
when the UDP is instantiated without an instance name).

Stu
~~~~~~~~~~~~~~~~~~~~~~~~~
Stuart Sutherland
stuart@sutherland-hdl.com
+1-503-692-0898
  

> -----Original Message-----
> From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On 
> Behalf Of Steven Sharp
> Sent: Thursday, August 11, 2005 12:10 PM
> To: gordonv@model.com; mcnamara@cadence.com; Mark.Hartoog@synopsys.com
> Cc: Brad.Pierce@synopsys.com; sv-bc@eda.org
> Subject: RE: [sv-bc] Is an unnamed block with declarations a scope?
> 
> 
> >From: "Mark Hartoog" <Mark.Hartoog@synopsys.com>
> 
> >A related issue to this is the naming of unnamed scopes. Even if you
> >cannot use heirachical names to access variables in unnamed blocks,
> >they still might appear in dump files and wave form displays, where
> >they need to be given a unique name. I think this can be accomplished
> >by just making up names for the unnamed scopes, similar to what is
> >done for unnamed generate blocks. I'm not sure it is an important
> >issue to standardize that naming convention across tools. 
> 
> It could be handy for things like tools that compare dump files with
> each other.  The value is the same as for unnamed generate blocks.
> It is not a huge benefit, but then the cost of defining a standard
> name is essentially zero, so the benefit/cost ratio is high.
> 
> Steven Sharp
> sharp@cadence.com
> 
> 
>