RE: [sv-ac] sequence as clocking event to covergroup

Tej,

 

I agree with your proposal. A sequence should trigger as many coverage
sample events as sequence thread matches.

Users have the ability to override the over-sampling by setting the
strobe property of the corresponding covergroup.

 

            Arturo

 

________________________________

From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
Singh, Tej
Sent: Wednesday, December 06, 2006 11:36 AM
To: sv-ac@eda.org
Subject: [sv-ac] sequence as clocking event to covergroup

 

Hi All,

 

I need guidance on use of sequence event as clocking event in
covergroup.

Please consider this example

 

sequence seq;

    @(posedge clk)

    req ##[1:$] ack;

endsequence

 

covergroup cg @(seq);

    coverpoint addr {

        bins a [] = {[0:7]};

        bins b [] = {[8:15]};

    }

endgroup

 

Because of the way 'seq' is written, multiple temporal threads can match
at a clock edge.

The question is, should each thread match generate a event i.e. should
covergroup 'cg'

be called to sample for every thread match. Or there should be only one
sequence event

at a clock edge.

 

The question is pertinent only when sequence is used as a clocking event
to covergroup,

since for covergroup the LRM says that if the clocking event occurs
multiple times in a 

timestep, the covergroup will also be sampled multiple times. 

 

I think it should generate multiple events since if there is a cover on
the same sequence,

as per LRM, each match will cause the action block to execute. But LRM
does not

talk about sequence event.

 

Thanks

Tej