RE: [sv-bc] unsized number literals

I also think 2'b11 is correct. My reasoning is as follows. (page numbers
quoted below

based on 1800-2009 LRM)

1) An unsized literal should at least contain 32 bits (page 37 of LRM)

2) All bits of the unsized value shall be set to the value of the
specified bit. (page 37 of LRM)

So in this example, the actual is at least 32bits wide with value of
"1111...111", while the

formal is 2-bits wide.

In my opinion, a warning would be nice, but I am not sure if LRM requires
this because of

the unsized nature of the constant.

Thanks

Logie

From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of Dhiraj
Kumar Prasad
Sent: Wednesday, August 04, 2010 5:05 AM
To: Bresticker, Shalom
Cc: Surya Pratik Saha; sv-bc@eda.org
Subject: Re: [sv-bc] unsized number literals

Hello Shalom,

Questa 6.6b display 2'b11.

-dhiRAj

Bresticker, Shalom wrote:

The conclusion of that thread seemed to be that 2'b11 would be the correct
answer here.

Shalom

From: Surya Pratik Saha [mailto:spsaha@cal.interrasystems.com]
Sent: Wednesday, August 04, 2010 2:53 PM
To: Dhiraj Kumar Prasad
Cc: Bresticker, Shalom; sv-bc@eda.org
Subject: Re: [sv-bc] unsized number literals

Hi Dhiraj,
I don't agree, I did not get anything explicit in LRM supporting your
answer. We have already discussed about that in past. See the mail thread
with subject "Query about '1" around early July 2008 time frame.

Regards
Surya

-------- Original Message --------
Subject: Re:[sv-bc] unsized number literals
From: Dhiraj Kumar Prasad <mailto:dhiraj@cal.interrasystems.com>
<dhiraj@cal.interrasystems.com>
To: Bresticker, Shalom <mailto:shalom.bresticker@intel.com>
<shalom.bresticker@intel.com>
Cc: <mailto:sv-bc@eda.org> "sv-bc@eda.org" <mailto:sv-bc@eda.org>
<sv-bc@eda.org>, Dhiraj Kumar Prasad <mailto:dhiraj@cal.interrasystems.com>
<dhiraj@cal.interrasystems.com>
Date: Wednesday, August 04, 2010 5:09:57 PM

Hello Shalom,

The correct behavior should be 2'b11 . Even I have tested the three
simulator and all are giving 2'b11 as output
with One of them is showing warning as port size differ in port connection.

-dhiRAj

Bresticker, Shalom wrote:

Consider the following code:

module top;

bot bot('1);

endmodule

module bot(input [1:0] i);

initial #10 $displayb(i);

endmodule

We have a port connection of '1 to a 2-bit port.

I would expect '1 to expand to 2'b11 without a problem.

In fact, the three simulators I tested showed different behaviors.

One did in fact show that i was assigned 2'b11 without any problem.

One simulator also assigned 2'b11 to i, but also issued a port-size mismatch
warning.

One simulator also issued such a warning and assigned 2'bz1 to i.

What is the correct behavior?

Thanks,

Shalom

Shalom Bresticker

Intel LAD DA, Jerusalem, Israel

+972 2 589 6582 (office)

+972 54 721 1033 (cell)

http://www.linkedin.com/in/shalombresticker

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