Fwd: Re: statement vs. statement_or_null

From: Stefen Boyd (stefen@boyd.com)
Date: Thu Oct 16 2003 - 16:01:47 PDT

  • Next message: Steven Sharp: "errata/494: another erratum"

    >Date: Tue, 14 Oct 2003 12:24:05 -0700
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    >Date: Tue, 14 Oct 2003 12:34:07 -0700
    >From: Bruce LaVigne <bruce@hp.com>
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    >To: mac@verisity.com
    >Cc: Shalom.Bresticker@motorola.com, etf@boyd.com
    >Subject: Re: statement vs. statement_or_null
    >References:
    ><Pine.GSO.4.10.10310132157500.21882-100000@eagle>
    ><Pine.GSO.4.10.10310140943500.27024-100000@eagle>
    ><16268.17728.635861.45245@gargle.gargle.HOWL>
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    >
    >I can think of two cases where it would be useful:
    > a) if there were compile directives (#ifdefs) which caused the entire
    > block to become null, and
    > b) during debug one might wish to comment out the entirety of a block,
    > but leave the surrounding control logic in place.
    >
    >Just my 2c,
    >
    >-bruce
    >
    >
    >Michael McNamara wrote:
    > > 1) I do not see any value in an empty begin..end block, (whether in a
    > > function or not in a function; and
    > >
    > > 2) I see only a small value to a loop with an empty body
    > > while ( do_more_work(a) ) ;
    > >
    > > 3) #1 is actually allowed by the current BNF, and also by all the
    > > tools that I haver access to, which I have cared to try.
    > >
    > > 4) #2 is not allowed by any of our tools, whether in a function or not
    > > in a function; and no user has ever complained. I do not believe
    > > that Verilog-XL or VCS accept this either.
    > >
    > > Throw the following at you favorite Verilog parser:
    > >
    > > module foo;
    > > reg a;
    > > initial while (a) ;
    > > end
    > >
    > > So I am against changing Syntax 9-7, so as to allow null statements in
    > > loops that occur in functions; as this is definately not an errata.
    > >
    > > As for Syntax 9-13, the BNF in my printed version of 1364-2001 says:
    > >
    > > function_seq_block :==
    > > begin [: block_identifier {block_item_declaration}]
    > > { function_statement } end
    > >
    > > and the { function_statement } production means "Zero or more
    > > instances" of function_statement, so I believe that the current BNF is
    > > fine, and needs no change.
    > >
    > > So I say we withdraw this errata.
    > >
    > > -mac
    > >
    > > -- On Oct 14 2003 at 09:44, Shalom.Bresticker@motorola.com sent a message:
    > > > To: etf@boyd.com
    > > > Subject: "Re: statement vs. statement_or_null"
    > > > Friends,
    > > >
    > > > I need your opinions on this ASAP.
    > > >
    > > > Thanks,
    > > > Shalom
    > > >
    > > > On Mon, 13 Oct 2003 Shalom.Bresticker@motorola.com wrote:
    > > >
    > > > > Date: Mon, 13 Oct 2003 22:00:28 +0200 (IST)
    > > > > From: Shalom.Bresticker@motorola.com
    > > > > To: Steven Sharp <sharp@cadence.com>
    > > > > Cc: etf@boyd.com
    > > > > Subject: Re: statement vs. statement_or_null
    > > > >
    > > > > And it seems not to allow a null statement in their function
    > equivalents
    > > > > as well.
    > > > >
    > > > > And the obvious reason seems to be that there is no point to a null
    > > > > statement in those places.
    > > > >
    > > > > I guess that means we should reconsider #229 and not include it
    > > > > in the 2001c errata sheet.
    > > > >
    > > > > Shalom
    > > > >
    > > > >
    > > > > On Mon, 13 Oct 2003, Steven Sharp wrote:
    > > > >
    > > > > > Date: Mon, 13 Oct 2003 13:05:52 -0400 (EDT)
    > > > > > From: Steven Sharp <sharp@cadence.com>
    > > > > > To: etf@boyd.com, Shalom Bresticker <Shalom.Bresticker@motorola.com>
    > > > > > Subject: Re: statement vs. statement_or_null
    > > > > >
    > > > > > Well, Verilog-XL doesn't allow a null statement in those
    > places. I don't
    > > > > > know that there is any good reason for that.
    > > > > >
    > > > > > Steven Sharp
    > > > > > sharp@cadence.com
    > > > > >
    > > > >
    > > > >
    > > >
    > > > --
    > > > Shalom
    > Bresticker Shalom.Bresticker@motorola.com
    > > > Design & Reuse Methodology Tel: +972 9
    > 9522268
    > > > Motorola Semiconductor Israel, Ltd. Fax: +972 9
    > 9522890
    > > > POB 2208, Herzlia 46120, ISRAEL Cell: +972 50
    > 441478
    > > >
    > >
    > >

    --------------------
    Stefen Boyd Boyd Technology, Inc.
    stefen@BoydTechInc.com (360)666-6957
    www.BoydTechInc.com

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