RE: [sv-ac] Question about usage of endpoints in class methods

Manisha, that is true, but in your example the sequence has a parameter
and so it could (should?) be constrcuted anew with every instance of the
class that maps to a different instance of the interface? It is true
that the interface instances are known, so it could pre-construct an
instance of the sequence for each of them, but still...
 
ed
 


________________________________

	From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf
Of Kulshrestha, Manisha
	Sent: Tuesday, May 16, 2006 4:30 PM
	To: Arturo Salz; sv-ac@eda.org
	Subject: RE: [sv-ac] Question about usage of endpoints in class
methods
	
	
	Hello Arturo,
	 
	Method triggered on a sequence can be called in a procedural
context so I do not think it should be illegal due to that reason. In
the LRM, there is an example in section 10.11 (Level sensitive sequence
controls) where .triggered is used on a sequence in procedural context
as follows:
	 
	sequence abc;

	@(posedge clk) a ##1 b ##1 c;

	endsequence

	sequence de;

	@(negedge clk) d ##[2:5] e;

	endsequence

	program check;

	initial begin

	wait( abc.triggered || de.triggered );

	if( abc.triggered )

	$display( "abc succeeded" );

	if( de.triggered )

	$display( "de succeeded" );

	L2 : ...

	end

	endprogram
	

	Yes, there is an error in the constructor as mentioned by you.

	Thanks.

	Manisha

________________________________

	From: Arturo Salz [mailto:Arturo.Salz@synopsys.com] 
	Sent: Tuesday, May 16, 2006 12:13 PM
	To: Kulshrestha, Manisha; sv-ac@eda.org
	Subject: RE: [sv-ac] Question about usage of endpoints in class
methods
	
	

	Manisha,

	 

	The statement "if( s0(ifc.clk).triggered)" ought to be illegal.
The sequence "s0" cannot instantiated in a procedural context. User can
accomplish this similar functionality using an expect statement. For
example, replacing the incorrect statement with:

	expect( @(posedge ifc.clk) 1 );

	The above statement is legal in a procedural context.

	 

	There seems to be another minor error in your example: I believe
the constructor was intended to be written as: function new (virtual if1
_ifc);

	 

	            Arturo

	 

	
________________________________


	From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf
Of Kulshrestha, Manisha
	Sent: Tuesday, May 16, 2006 10:54 AM
	To: sv-ac@eda.org
	Subject: [sv-ac] Question about usage of endpoints in class
methods

	 

	Hi,

	 

	I have a question regarding usage of endpoints in class methods.
I would like to know if this is legal or allowed by LRM. I could not
find any restrictions in the LRM regarding this. But since class objects
are dynamic in nature, how is it supposed to work if class object gets
created sometime after first clock tick. Here is an example which uses
virtual interface inside class. As you can see from the example the
clock passed to the endpoint is dynamic and different for different
objects of the same class. Also, note that class object c4 is getting
created at time 50 where as the first clock tick for the endpoint in the
method is at 40. 

	 

	interface if1(clk);
	input clk;

	endinterface

	 

	module A;
	    reg bla;
	    reg clk1, clk2;

	 

	    sequence s0(clk);
	        @(posedge clk) 1;
	    endsequence

	 

	    class ctype;
	      virtual if1 ifc;
	      function new (virtual abc _ifc);
	        ifc = _ifc;
	      endfunction

	 

	      task execute();
	        if (s0(ifc.clk).triggered)
	           $display($time, ": sequence triggered");
	      endtask
	    endclass

	 

	    if1 abc1(clk1);
	    if1 abc2(clk2);

	 

	    ctype c3 = new(abc1);
	    ctype c4;

	 

	    initial
	    begin
	    clk1 = 0;
	    clk2 = 0;

	    #50 c4 = new(abc2);
	    end

	 

	    always #20 clk1 = ~clk1;
	    always #40 clk2 = ~clk2;

	 

	endmodule

	 

	Thanks.

	Manisha