[sv-ec] fixing typo in RE: Mantis 2506: interaction between expressions, range list items, and distribution to bins for a coverpoint

Hi Folks:

In the description of item #3 below, "with_expression" should have been
"set_expression".

J.H.

From: Havlicek John-R8AAAU
Sent: Thursday, November 25, 2010 11:14 AM
To: 'sv-ec@eda.org'
Cc: Havlicek John-R8AAAU; Little Scott-B11206; 'Mehdi Mohtashemi'
Subject: Mantis 2506: interaction between expressions, range list items,
and distribution to bins for a coverpoint

Hi Folks:

In the last SV-EC meeting, someone (Ray?) asked how a with_expression or
set_expression for a coverpoint should interact with open_range_list
items and the distribution of values to bins for a coverpoint.

I thought about this from the inception of the work on this proposal.
My initial technical notes are in the proposal_sketch.txt file uploaded
on to 2506.

My basic ideas are as follows. An open_range_list should be thought of
as a list of ordered sets (or a list of lists if you want). This allows
a value to appear multiple times in the list, but within one of the
ordered sets of the list a value can appear at most once. This is the
only mathematical structure needed to support the distribution of values
to a fixed number of bins as I understand it. The reference algorithm
for the distribution policy applies to a list of ordered sets.

If we add symbolic mechanisms, notably expressions, for defining sets,
the same infrastructure will work provided we have a way to order the
elements of a set specified by the new mechanism. If we do this, then
the new mechanism can participate along with other open_range_list items
to define ordered sets in the list of ordered sets.

The lastest proposal does not go so far as to add the capability of
specifying a list of sets defined by expressions. Nor does it allow
expressions to be intermingled with open_range_list items. But this
area of expansion of the capabilities remains open.

For coverpoints, the proposal adds expressions in three ways:

1. "{open_range_list} with (with_expression)". This serves to
intersect each ordered set specified by the open_range_list with the set
specified by the with_expression.

2. "cover_point_identifier with (with_expression)". This serves
to define a single ordered set consisting of all values of the type of
the coverpoint that are in the set specified by the with_expression.
The coverpoint type has to be ordinal in order for this set to make
sense as an ordered set.

3. "<set_expression>". This serves to define a single ordered set
consisting of all values of the type of the coverpoint that are in the
set specified by the with_expression. Again, the coverpoint type has to
be ordinal in order for this set to make sense as an ordered set.

Once one understands the list of ordered sets specified, the reference
algorithm for distributing values can be applied.

J.H.

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