Subject: Re: BNF question
From: Shalom.Bresticker@motorola.com
Date: Wed Apr 17 2002 - 09:58:56 PDT
I imagine it was made illegal because it makes the length of the expression
uncomputable at compilation time.
It might not be so bad in Verilog-XL, which is semi-interpreted, but in a
code compiler, such as NC, it is probably a problem.
Shalom
On Wed, 17 Apr 2002, Paul Graham wrote:
> > initial
> > mytask( {foo{a}} ); // multiple concat with non-constant replication
> > endmodule
>
> > Unfortunately, a customer has run this on XL and NC, and they both allow it.
> > Can someone with access to these simulators verify this (and maybe check VCS
> > too)? Should it be an error? If not, then I fear that Stefen has more work
> > to do 8-).
>
> I can check it out, but what do you want me to check out :-? Whether
> a multi-concatenation repeat count can be non-constant? The LRM says
> it has to be constant.
>
> Verilog-XL reports a warning for a non-constant repeat count, but supports
> it anyway.
>
> NC reports an error.
>
> I wonder why it was made illegal? Because it's hard to synthesize?
-- Shalom Bresticker Shalom.Bresticker@motorola.com Principal Staff Engineer Tel: +972 9 9522268 Motorola Semiconductor Israel, Ltd. Fax: +972 9 9522890 POB 2208, Herzlia 46120, ISRAEL Cell: +972 50 441478
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