Re: [sv-ec] Covergroup fixed-size vector bin creation

<resending to the alias -- there were quite a few addresses that bounced>

-------- Original Message --------
Subject: [sv-ec] Covergroup fixed-size vector bin creation
Date: Tue, 15 Mar 2011 13:02:35 +0000
From: Little Scott-B11206 <B11206@freescale.com>
To: sv-ec@eda.org <sv-ec@eda.org>
CC: Fais Yaniv-RM96496 <RM96496@freescale.com>

Hi all:

In the meeting yesterday we discussed the order in which the bin distribution and with
expression application should be done when creating fixed-size vector bins. Below is
an example of where this would matter.

bit [3:0] coverpoint b {
   bins onehot[4] = b with $onehot(item);
}

If we apply the with function and then distribute to the bins we get what is probably the
intended result of one item/bin. If we distribute then apply the with function we end up
with three bins, <0001,0010>,<0100>,<1000>. The fourth bin is emptied by the application
of the with expression and is excluded from coverage.

In the meeting, I had stated that I thought the application of the with expression should
apply after the distribution of bins. This would be in line with how ignore bins are
handled (see 19.5.4). Based on the above example it seems like that is the wrong thing
to do. Do folks recall how the decision was made regarding ordering between applying
ignore bins and distribution? Is there another example that shows why distribution
before application of the with expression is desirable?

Thanks,
Scott

-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.