[sv-ec] RE: Query on bin value with x or z bits

Hi Shalom,

I was assigned the task of writing a modification for the text. You may refer to Mehdi's meeting notes.
Anyway, the basic issue as I remember was that for non-wildcard bins we should allow values with x/z
(and should not generate warning as stated) but if we do that computing coverage space becomes a problem,
because we have to do x/z based arithmetic. There may be something else also which others can clarify.

Regds,
Swapnajit

________________________________
From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com]
Sent: Tuesday, December 21, 2010 9:18 PM
To: Swapnajit Chakraborti; sv-ec@eda.org
Cc: Devraj Goyal
Subject: RE: Query on bin value with x or z bits

I found that the text in 19.5.6 was added in Mantis 1313 in May-June 2006. The text was written by Gord V.

Shalom

From: Bresticker, Shalom
Sent: Tuesday, December 21, 2010 2:10 PM
To: 'Swapnajit Chakraborti'; sv-ec@eda.org
Cc: Devraj Goyal
Subject: RE: Query on bin value with x or z bits

Hi,

Was this ever resolved? Or did someone file a Mantis issue on it?

Regards,
Shalom

From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of Swapnajit Chakraborti
Sent: Wednesday, August 04, 2010 4:42 PM
To: sv-ec@eda.org
Cc: Devraj Goyal; Swapnajit Chakraborti
Subject: [sv-ec] RE: Query on bin value with x or z bits

We would appreciate some comment regarding this query.

Regds,
Swapnajit

________________________________
From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of Devraj Goyal
Sent: Thursday, July 29, 2010 4:03 PM
To: sv-ec@eda.org
Subject: [sv-ec] RE: Query on bin value with x or z bits
Friendly reminder !!

Please let us know your comments on this.

Thanks,
Devraj

From: Devraj Goyal
Sent: Tuesday, July 27, 2010 5:33 PM
To: sv-ec@eda.org
Subject: Query on bin value with x or z bits

I have a query regarding value of coverbin when open_range_list yields a value with x or z bits.

Example:
logic [3:0] cp_var;
covergroup cg;
            CP: coverpoint cp_var{
                        bins b1 = {4'b1zx0, 4'b01xz};
                        bins b2 = {[4'b1zx0:4'b01xz]};
                        bins b3[] = {[4'b1zx0:4'b01xz]};
            };
endgroup

P1800-2009 LRM says (sec 19.5.3)
"When a bin definition includes an X or Z,
it indicates that the bin count should only be incremented when the sampled value has an X or Z in
the same bit positions, i.e., the comparison is done using ===."

Sec (19.5.6) says a warning needs to be given if open_range yields a value with any x or z bits for non wildcard bins,
and the following rules will be applied:

1) If an element of a bins open_range_list is a singleton value b, the element shall not participate in
the bins values.
2) If an element of a bins open_range_list is a range [b1 : b2] and either b1 or b2 contains any x or
z bits or every value in the range would generate a warning, then the element shall not participate in
the bins values.

Both these comments seem to be contradicting.
Should we always ignore X/Z values for non wildcard bins?

Please let us know what should be the correct behavior.

Also, is it valid to specify open_range_list as defined in bins b2 and b3.

Thanks,
Devraj

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