Re: BTF B19 - Signed Arithmetic Proposal (Updated)

From: Thomas Fitzpatrick (tfitz@cadence.com)
Date: Mon Mar 09 1998 - 05:55:37 PST

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On Mar 6, 8:49pm, Stuart Sutherland wrote:
> Subject: Re: BTF B19 - Signed Arithmetic Proposal (Updated)
> Tom,
>
> Just a nit, but the following statement could be interpreted as conflicting
> with the concept that the signed attribute can be declared at either the
> port declaration or the net/register declaration.
>
> >Page 15 (Section 3.3.1 Specifying vectors - 3rd Paragraph)
> > Vector nets and registers shall obey laws of arithmetic modulo 2 to the
> >power n(2^n), where n is the number of bits in the vector. Vector nets and
> >registers shall be treated as unsigned quantities, unless the net or
register
> >is declared to be signed.
>
> I think the wording proposed in section 12 about declaring the signed
> attribute on either the port or the net/reg declaration is strong enough to
> resolve any ambiguity. But, since the description about the signed
> attribute on a port doesn't occur until much later (section 12), perhaps
> more clear wording in this section might be to change the last sentence to:
>
> Vector nets and registers shall be treated as unsigned quantities, unless
> the net or register
> is declared to be signed or is connected to a port that is declared to be
> signed.

        You're right, it is a little ambiguous. I've added your suggestion, as
well as a cross-reference to section 12.3.2 which talks about declaring signed
nets, regs and ports.

Thanks for catching this,
-Tom 

-- 
---------------
Tom Fitzpatrick

Cadence Design Systems           Cobra Technical Marketing Manager
Product Engineering              Logic Design & Verification Business Unit
(978)446-6438                    x6438

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