[sv-ec] RE: Query regarding wildcard arithmetic expressions in wildcard bin definition

Hi,

One might so interpret, but such an interpretation would be inconsistent with other parts of the language, in my opinion.

Shalom

From: Irfan Chandurwala [mailto:irfanc@cadence.com]
Sent: Friday, January 18, 2013 07:00
To: Bresticker, Shalom; sv-ec@eda.org
Subject: RE: Query regarding wildcard arithmetic expressions in wildcard bin definition

Thanks Shalom,

What you have sited applies in case of casex, we agree with it and this is acceptable if we encounter such arithmetic expression at other places
in the design, but in case of coverbin definition, wrt LRM section 19.5.6 on value resolution, one can have a different interpretation.
One could have a different view point like: "evaluation of bin expression (b) should be done ""after"" replacing x/z with 0 and 1"
Please comment on this.

Section 19.5.6 :
".....
A coverpoint expression and the expressions in a bins construct are involved in comparison operations in
order to determine into which bins a particular value falls. Let e be the coverpoint expression and b be an
expression in a bins open_range_list. The following rules shall apply when evaluating e and b: For wildcard
bins, x and z values in b shall be treated as all possible 0 and 1 values prior to applying these rules.
.....  "


Regards,
-Irfan


From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com]
Sent: Thursday, January 17, 2013 4:30 PM
To: Irfan Chandurwala; sv-ec@eda.org<mailto:sv-ec@eda.org>
Subject: RE: Query regarding wildcard arithmetic expressions in wildcard bin definition

I think:

Actually, 2'b0x + 1 will give you 32'bx.

I will give another example. In a casex statement, 2'b0x in a case item expression means that the LSB is don't care.
Again, if you give an expression and not just a single number, first the expression is evaluated, and only afterwards is the resulting value interpreted.

Shalom

From: owner-sv-ec@eda.org<mailto:owner-sv-ec@eda.org> [mailto:owner-sv-ec@eda.org] On Behalf Of Irfan Chandurwala
Sent: Wednesday, January 16, 2013 07:50
To: sv-ec@eda.org<mailto:sv-ec@eda.org>
Subject: [sv-ec] Query regarding wildcard arithmetic expressions in wildcard bin definition

Hi

My query is regarding "what must be correct behavior when arithmetic expression involving wildcard values is part of wildcard bin definition"

Ex ::

reg [1:0] a ;
covergoup cg;
    coverpoint a {
            wildcard bins b[] = {2'b0x + 1}; // --> what must be possible bins values ???
    }
endgroup

Ques 1) In the above example what must be the possible bin values in the wildcard bins b1.
Options

a)    0,1,2,3

b)    0,1

c)     Any other possible value


Ques 2 ) Which of the below explanation is correct -

1      evaluation of "2'b0x + 1", which is 2'bxx as per LRM section 11.4.3, will be done first and then expansion of wildcard value, which will give us {0,1,2,3} as possible bin values

2      expansion of wildcard value "2'b0x" will be done first and then evaluation of arithmetic expression, which will give us {0,1} as possible bin values

3      Or is there any other behavior for such scenario.

Regards,
-Irfan

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