Re: [sv-bc] Question on const declaration RHS

From: Surya Pratik Saha <spsaha_at_.....>
Date: Tue Sep 23 2008 - 11:55:18 PDT

Hi Dave,
Here is the 1800-2005 LRM text:
A static constant declared with the const keyword can be set to an expression of literals, parameters, local parameters, genvars, enumerated names, a constant function of these, or other constants.

This does not match with your statement.

Regards
Surya

-------- Original Message  --------
Subject: Re:[sv-bc] Question on const declaration RHS
From: Rich, Dave <Dave_Rich@mentor.com>
To: Surya Pratik Saha <spsaha@cal.interrasystems.com>, sv-bc@eda.org
Date: Tuesday, September 23, 2008 9:45:51 PM

Surya,

A "const" does not affect the RHS of the declaration. Whatever is
allowed for a non-cost variable declaration is allowed for a const. In
fact, a const variable declared inside an automatic block is initialized
every time the block is entered to whatever is the current value of the
RHS expression. It's just that a const variable becomes read-only after
initialization.

Dave


  

-----Original Message-----
From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org]
    

On
  

Behalf Of Surya Pratik Saha
Sent: Tuesday, September 23, 2008 12:45 AM
To: sv-bc@server.eda.org
Subject: [sv-bc] Question on const declaration RHS

Hi,
As per SV 1800 LRM, the RHS side of 'const' declaration should be
consisting of normal const_expression or anything which is already
declared by another 'const' declaration.

But consider the e.g. below:
module top;
    int x;
    function int f(input y);
        x = 1;
        return f + x;
    endfunction
    const int r1 = f(1); // function 'f' is not a constant as it used
    

a
  

global non-parameter variable 'x'
    const int r2 = x; // 'x' is not declared with 'const'
endmodule

Most of the standard simulators pass the case. Is it a bug in the
simulators? Also OVM package has this type of declaration too which is
against LRM. Please comment.

--
Regards
Surya




--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
    

--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean. Received on Tue Sep 23 11:56:38 2008