Re: Attributes and constant expressions


Subject: Re: Attributes and constant expressions
From: Michael McNamara (mac@verisity.com)
Date: Wed Oct 24 2001 - 14:39:11 PDT


Stefen Boyd writes:
> Precedence: bulk
>
> At 12:06 PM 10/24/2001 -0500, Adam Krolnik wrote:
> > > // ambit synthesis off
> > > ...
> > > // ambit synthesis on
> >
> >Something similar to
> >
> >`ifndef SYNTHESIS
> >...
> >`endif
>
> Since we didn't create attributes in a way that would
> accomplish synthesis on/off behavior, perhaps what we
> should do is require synthesis tools to define a compile
> time macro so that Adam's example would work as a
> replacement of the comment-style on/off flags. That
> way we can depricate all the comment-style commands by
> having all of them covered. Without defining a compile
> time macro name, we're left with metacomments as
> defined in section 6.1 of 1364.1

 Reading your email made me think of (ugly as it may appear) the idea
 of adopting convention of

 initial (* synthesis = 0 *);

 assign debuging_register = f(a,b,c,d);

 initial (* synthesis = 1 *);

 assign w = a + b + c;

however there is not any notion of 'regions' or persistance for
attributes. I.E., when parsing the first assignement, if you look up
the attributes that apply to it, the value of 'synthesis' is
undefined.

Here I go back to the tick defines that design compiler should have
supported in 1990:
 
 `ifndef SYNTHESIS
 assign debuging_register = f(a,b,c,d);
 `endif

Absolutely simple; very clean; any programmer having no experience
with HDLs first guess as to what the above means would be spot on
correct.

*sigh*
    
>
> I would like to see section 6.1 indicate that metacomments
> are depricated in general.
>
> Regards,
> Stefen
>
>
> --------------------
> Stefen Boyd Boyd Technology, Inc.
> stefen@BoydTechInc.com (408)739-BOYD
> www.BoydTechInc.com (408)739-1402 (fax)
>
>



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