RE: [sv-bc] Mantis 1984

I think you are both correct.

I think there is an implicit "Therefore, ", i.e.,

"A continuous assignment shall be implied when a variable is connected
to an input port declaration. [Therefore,] assignments to variables
declared as an input port shall be illegal." 

What the added sentence does is cover the case where the input port is
unconnected. Some people might have considered that case ambiguous.

Shalom


> -----Original Message-----
> From: owner-sv-bc@server.eda.org 
> [mailto:owner-sv-bc@server.eda.org] On Behalf Of Brad Pierce
> Sent: Friday, January 04, 2008 3:01 AM
> To: sv-bc@server.eda.org
> Subject: RE: [sv-bc] Mantis 1984
> 
> According to 22.3.3.2 (draft 4) --
> 
>   "Assignments to variables declared as an input port shall 
> be illegal."
> 
> Isn't that sufficient to make the assignment to C illegal?
> 
> -- Brad
> 
> -----Original Message-----
> From: Gordon Vreugdenhil [mailto:gordonv@model.com]
> Sent: Thursday, January 03, 2008 4:44 PM
> To: Brad Pierce
> Cc: sv-bc@eda.org
> Subject: Re: [sv-bc] Mantis 1984
> 
> 
> 
> Brad Pierce wrote:
> > Following up to
> > 
> >    http://www.eda-stds.org/sv-bc/hm/7774.html
> > 
> > In the following example, only the first assignment is legal?
> > 
> > 
> > module test(input logic A, input logic B, input var C, D );
> >   assign A = 0;  // legal
> >   always @* begin
> >       B = A ;    // illegal to procedurally assign to wire
> >       C = A ;    // illegal to assign to input variable
> 
> I agree, but the reason that it is illegal is due to the
> procedural/continuous conflict on "C".  An "input" variable port is
> assumed to have a continuous driver on it; that is the reason that the
> procedural assignment is illegal.  The continuous assignment 
> to "D" (the
> next assignment) is illegal since that means there are multiple
> continuous assignments on "D" -- the assumed one on the high side and
> the explicit one in the module.
> 
> It would, for example, be perfectly legal to "force"
> any of the vars even though they are inputs since "force"
> does not count as either procedural or continuous in terms of 
> the driver
> considerations.
> 
> Gord.
> 
> 
> >   end
> >   assign D = 0;  // illegal to assign to input variable endmodule
> > 
> > 
> > -- Brad
> > 
> > 
> 
> --
> --------------------------------------------------------------------
> Gordon Vreugdenhil                                503-685-0808
> Model Technology (Mentor Graphics)                gordonv@model.com
> 
> 
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