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

first_match will only prune out threads from the same attempt.
Multiple attempts matching at the same clock should still
cause multiple covergroup sampling.

Even 'req ##1 ack[->1]' can have multiple attempts matching
at the same clock.

Tej


-----Original Message-----
From: Eduard Cerny [mailto:Eduard.Cerny@synopsys.com]
Sent: Wed 12/6/2006 1:56 PM
To: Arturo Salz; Singh, Tej; sv-ac@eda.org
Subject: RE: [sv-ac] sequence as clocking event to covergroup
 
Also, by applying first_match to the sequence expression or writing it
so that the sequence is deterministic. e.g., req ##1 ack[->1];
ed
 


________________________________

	From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf
Of Arturo Salz
	Sent: Wednesday, December 06, 2006 3:58 PM
	To: Singh, Tej; sv-ac@eda.org
	Subject: 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