Re: gEDA-user: Yet another Icarus question

[Stephen Williams <steve@xxxxxxxxxx>]

This looks like a bug in Icarus Verilog, I'm afraid. Since all the
values in your expression have explicit sizes, the bit width need
not have carry space tacked on and the width should be 26bits.
In fact, in your example the bus is particularly nasty because it
causes the enablemask bits to be shifted up a bit in the concatenation!

I see that you filed a bug report, that's good. I'll probably bump
its priority a notch because in certain situations it is giving an
incorrect result without warning.

Patrick Doyle wrote:
> Can anybody tell me if the following is an Icarus feature or a Verilog
> feature.  I would expect the two $display statements to show the same
> results.  For some reason, the first one expands the result to 27 bits
> instead of the 26 bits I would have expected.  The only difference
> (hopefully) between the two lines of code is the addition of a set of
> parentheses.

> Obviously, I don't really think this is a "feature", but is likely to
> be a "bug".  But before I make such hasty accusations, I thought I
> would ask for some other opinions (knowing full well that Cary and
> Stephen follow this list :-))  I am running:
> 
> Icarus Verilog version 0.10.0 (devel) (s20090923-223-g9fbb12d)
> 
> If it is agreed that this is a bug, I can file the report.
> 
> --wpd
> 
> module check_this;
> 
> reg [5:0] offset;
> reg [9:0] enablemask;
>    initial begin
>      enablemask = 10'b00000_00110;
>      offset     = 0;
>      $display("%b", {enablemask, (16'h0 +  8'h80 + offset )});
>      $display("%b", {enablemask, (16'h0 + (8'h80 + offset))});
>    end
> endmodule // check_this
> 
> 
> _______________________________________________
> geda-user mailing list
> geda-user-3OLirty5fqqAvZLjymCQLg@xxxxxxxxxxxxxxxx
> http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
> 


-- 
Steve Williams                "The woods are lovely, dark and deep.
steve at icarus.com           But I have promises to keep,
http://www.icarus.com         and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user