[sv-bc] RE: [sv-ec] Is instance constant allowed outside class?

In my opinion this is not good idea to allow user skip the initialization of
const variable.
This only confuses the user and adds no value to the language.
 
I agree with Surya that if conts with initialization should really be
alllowed then LRM should be rewritten both chapters - about const and about
const in classes.
I would prefer to rewrite them and say that const must have an initaliation.
 
 
DANiel

  _____

From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of Rich,
Dave
Sent: Thursday, April 01, 2010 6:45 AM
To: Surya Pratik Saha
Cc: sv-ec@eda.org; sv-bc@eda.org; Bijoy Gopal Nandy
Subject: RE: [sv-ec] Is instance constant allowed outside class?

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. Hierarchical names

are allowed because constants declared with the const keyword are calculated
after elaboration.

const logic option = a.b.c ;

An automatic constant declared with the const keyword can be set to any
expression that would be legal

without the const keyword.

Note the use of the word can, not shall. There is no requirement that it has
to have an assignment. I would expect the behavior to be the same as a
non-const variable. The const keyword is a modifier that prevents further
assignments to that variable. That is all that it does.

Dave

From: Surya Pratik Saha [mailto:spsaha@cal.interrasystems.com]
Sent: Wednesday, March 31, 2010 9:11 PM
To: Rich, Dave
Cc: sv-ec@eda.org; sv-bc@eda.org; Bijoy Gopal Nandy
Subject: Re: [sv-ec] Is instance constant allowed outside class?

Hi Dave,
I could not find anything in "6.20.6" where it allows const declaration
without initialization. Please let me know if there is any LRM
specification.

Also, it is not clear what is the value of using a const declared variable
which does not have initialization, will it take default value (like for 4
state, it will be all 'x', and for 2 state it will be all '0')?

And if 'global constant' can be declared without initialization, then I
think some rewriting is required in "8.18 Constant class properties",
otherwise it is very confusing.

Regards
Surya

-------- Original Message --------
Subject: [sv-bc] RE: [sv-ec] Is instance constant allowed outside class?
From: Rich, Dave <mailto:Dave_Rich@mentor.com> <Dave_Rich@mentor.com>
To: Surya Pratik Saha <mailto:spsaha@cal.interrasystems.com>
<spsaha@cal.interrasystems.com>, sv-ec@eda.org, sv-bc@eda.org
Cc: "Bijoy Gopal Nandy" <mailto:bijoy@cal.interrasystems.com>
<bijoy@cal.interrasystems.com>
Date: Wednesday, March 31, 2010 8:21:05 PM

Yes, see section 6.20. There is no requirement to have an user specified
initialization.
 
The name global constant is a misnomer. It behaves like any other const,
which means it can take on different values each time the variable comes
into existence because the initialization expression may evaluate
differently.
 
The only thing special about a class instance constant is that it is
allowing a "write" to the const variable in the constructor instead of
the declaration initialization.
 
  

-----Original Message-----
From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
    

Surya
  

Pratik Saha
Sent: Wednesday, March 31, 2010 7:19 AM
To: sv-ec@eda.org; sv-bc@eda.org
Cc: Bijoy Gopal Nandy
Subject: [sv-ec] Is instance constant allowed outside class?
 
Hi,
"8.18 Constant class properties" of SV 2009 LRM defines two types of
constants - global constant (initialization is must) and instance
constant (initialization is missing). Is it allowed to use that
    

instance
  

constant syntax in non-class scope? For e.g.:
module top;
    const int x; // Is it allowed?
endmodule
 
OR
module top;
    class C;
       function f;
          const int x; // Is it allowed
       endfunction
    endclass
endmodule
 
Some standard tools pass both the cases. Also OVM 2.1.1 has 2nd type
    

of
  

syntax usage in its source. Please let me know.
 

--
Regards
Surya
 
 
 
 
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