Re: [sv-bc] E-mail Ballot Due Dec 17 8AM PST

From: Don Mills <mills_at_.....>
Date: Mon Dec 17 2007 - 08:54:25 PST

Alsop, Thomas R wrote:

SVDB 2037 ___Yes   _X_No (Just want a couple questions clarified before I change to yes)
http://www.eda.org/svdb/view.php?id=2037

In example 3, is there a dependency on the order of the “instance” lines.  In other words do I have to override the .WIDTH(32) _before_ I override top.a1 on the next line?  What if I reversed the order of these lines?  Any issues there that we need to consider or clarify in the proposal?

  config cfgl;

    design rtlLib.top;

    instance top use #(.WITDH(32));

    instance top.a1 use #(.W(top.WIDTH));

  endconfig

It must be defined before it  is used.  If the order is switched, top.a1 gets the value of WIDTH before the override of WIDTH.  I am following the rule - you must declare it before you use it.  Should I note in the proposal?

In example 4, do we need to consider the semantic difference between parameter vs localparam.  For example, if I have a localparam in top4 for WIDTH, this in essence means I don’t want to change this value.  If I am using a “parameter” in the config to override this, is this okay?  To avoid this type of confusion, perhaps all config parameters should be localparam?  

A parameter or localparam can be used in a configuration to represent a value sent to multiple instances.

 

  module top4 ();

    parameter WIDTH = 16;

    adder a1 #(.ID(“a1”))(...);

    adder a2 #(.ID(“a2”))(...);

    adder a3 #(.ID(“a3”))(...);

    adder a4 #(.ID(“a4”))(...);

  endmodule

 

  config cfg2;

    localparam S = 24

    design rtlLib.top4;

    instance top4.a1 use #(.W(S));

    instance top4.a2 use #(.W(S));

  endconfig

There is no need for parameter at this time in the proposal.  Localparam would meet the requirements.  Parameter was put in for part of a feature that I was proposing that eventually got yanked from this go around.  I would prefer leave both parameter and localparam in but I could pull parameter it is necessary.

-- 
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Don Mills
mills@lcdm-eng.com
www.lcdm-eng.com
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