RE: $arandom/$rdist_ seeds

In SV, the number BNF is unsigned. A sign is added as a unary plus or minus operator that precedes the number.

Note that the seed of the digital $random must be a variable.

Shalom

> -----Original Message-----
> From: owner-verilog-ams@eda.org [mailto:owner-verilog-ams@eda.org] On
> Behalf Of Dave Miller
> Sent: Wednesday, May 23, 2012 22:46
> To: Paul Floyd
> Cc: verilog-ams@eda-stds.org
> Subject: Re: $arandom/$rdist_ seeds
>
> Hi Paul, well yes it should allow them.
> But the issue is a lot deeper than that.
>
> In LRM 2.2 we had the definition:
> decimal_number ::=
> [ sign ] unsigned_num
>
> But in 2.3 we changed that to:
> decimal_number ::=
> unsigned_number
> | [ size ] decimal_base unsigned_number
> | [ size ] decimal_base x_digit { _ }
> | [ size ] decimal_base z_digit { _ }
>
> It looks like we inherited it blindly from digital.
>
> If I look at Digital 1364 1995 it is defined as
> decimal_number ::=
> [ sign ] unsigned_number
> | [ size ] decimal_base unsigned_number
>
> But 1364-2001 (and hence SV 1800)
> decimal_number ::=
> unsigned_number
> | [ size ] decimal_base unsigned_number
> | [ size ] decimal_base x_digit { _ }
> | [ size ] decimal_base z_digit { _ }
>
> So is this a bug in digital? In 1800-2009, If I look at the rule for
> primary
> (one of the basic building blocks for an expression) it uses
> primary_literal,
> which uses number, which uses decimal_number. But that doesn't allow
> signed
> values? So we can't have -ve numbers anymore?
>
> Dave
>
> On 05/23/2012 12:11 PM, Paul Floyd wrote:
> > Hi
> >
> > The seeds for these system functions can be "decimal_number". The
> EBNF for that is
> >
> > decimal_number ::=
> > unsigned_number
> > | [ size ] decimal_base unsigned_number
> > | [ size ] decimal_base x_digit { _ }
> > | [ size ] decimal_base z_digit { _ }
> >
> > I can't see how negative numbers are allowed. Shouldn't that
> possibility be
> >
> > "[sign]decimal_number"?
> >
> > Regards
> > Paul
>
> --
> ==============================================
> -- David Miller
> -- Design Technology (Austin)
> -- Freescale Semiconductor
> -- Ph : 512 996-7377 Fax: x7755
> ==============================================
>
>
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