Re: `default_transition

Prasanna and others,

I think reducing the constant_expression in this case to a single real 
number is a bit too harsh. What is needed is the concept of a compiler 
directive constant expression, that can only contain integers, reals, 
arithmetic operators, and macros (in a limited form). This would allow 
such things as:

        `default_transition 1.2 * `MY_DEFAULT_TRANSITION_TIME

So the syntax would become:
        default_transition_compiler_directive ::=
                  `default_transition transition_time
        transition_time ::=
                  compiler_directive_constant_expression
        compiler_directive_constant_expression ::=
                  compiler_directive_constant_primary
                | unary_operator compiler_directive_constant_primary
                | compiler_directive_constant_expression binary_operator
                  compiler_directive_constant_expression
        compiler_directive_constant_primary ::=
                  decimal_number
                | real_number
                | compiler_directive_constant_expression_macro
        compiler_directive_constant_expression_macro ::=
                  `define text_macro_name 
compiler_directive_constant_expression

On the other hand, if the only actual use of the default transition 
compiler directive is with numbers only, I have no problem with reducing 
the constant expression to a real number. I do think that it is useful to 
have access to macros as that would allow more control over this compiler 
directive, for instance from the command line -- assuming the 
simulator/compiler supports the definition of macros from the command line 
(which is not in the standard).

Regards,
Marq


Marq Kole
Competence Leader Analog Simulation, Philips ED&T











Tamhankar Prasanna-A14507 <Prasanna.Tamhankar@freescale.com>
Sent by: 
owner-verilog-ams@eda.org
03-05-2005 09:48
 
        To:     "'verilog-ams@eda.org'" <verilog-ams@eda.org>
        cc:     (bcc: Marq Kole/EHV/RESEARCH/PHILIPS)
        Subject:        `default_transition
        Classification: 




Hi all,

Currently, the syntax for `default_transition is 
                 default_transition_compiler_directive ::=
                                 `default_transition transition_time
                 transition_time ::=
                                 constant_expression

Because `default_transition can *only* be outside a module scope, one 
cannot have any constant_expression for the transition_time (because 
constant_expression includes module specific things too, like 
parameter_identifier) , this should be changed to 

                 transition_time ::= 
                                 real_number

Thanks,
Prasanna
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Prasanna Tamhankar
Freescale Semiconductors, Adelaide
+61 8 81683585
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