RE: [sv-ec] random generator state for shallow copy

In 8.11 the LRM states:
A shallow copy executes in the following manner:

1) An object of the class type being copied is allocated. This
allocation shall not call the object's constructor
or execute any variable declaration initialization assignments.

2) All class properties, including the internal states used for
randomization and coverage are copied to
the new object. Object handles are copied; this includes the object
handles for covergroup objects
(see Clause 19). An exception is made for embedded covergroups (see
19.4). The object handle of
an embedded covergroup shall be set to null in the new object. The
internal states for randomization
include the random number generator (RNG) state, the constraint_mode
status of constraints, the
rand_mode status of random variables, and the cyclic state of randc
variables (see Clause 18).

3) A handle to the newly created object is assigned to the variable on
the left-hand side.


So Yes,  the RNG state is copied and the same values should be
randomized.
 
Ray
 



________________________________

	From: owner-sv-ec@server.eda.org
[mailto:owner-sv-ec@server.eda.org] On Behalf Of Daniel Mlynek
	Sent: Wednesday, December 16, 2009 7:34 AM
	To: 'Bresticker, Shalom'; sv-ec@server.eda.org
	Cc: 'Mirek Forczek'
	Subject: RE: [sv-ec] random generator state for shallow copy
	
	
	Yes this is what I know. The problem is with copying RNG state
during shallow copy. Should it be copied or no?
	If this is copied then should same values be randomized?
	 
	DANiel

________________________________

	From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com] 
	Sent: Wednesday, December 16, 2009 4:27 PM
	To: Daniel Mlynek; sv-ec@server.eda.org
	Cc: 'Mirek Forczek'
	Subject: RE: [sv-ec] random generator state for shallow copy
	
	
	Hi,
	 
	The LRM says,
	"p2 = new p1;

	The last statement has new executing a second time, thus
creating a new object p2, whose class properties are copied from p1.
This is known as a shallow copy. All of the variables are copied across
integers, strings, instance handles, etc. Objects, however, are not
copied, only their handles; as before, two names for the same object
have been created. This is true even if the class declaration includes
the instantiation operator new"

	Thus since i is a variable, not an object handle, c1.i and c2.i
are independent data objects. If i was an object handle, then c1.i and
c2.i would point to the same object.

	Shalom


________________________________

		From: owner-sv-ec@server.eda.org
[mailto:owner-sv-ec@server.eda.org] On Behalf Of Daniel Mlynek
		Sent: Wednesday, December 16, 2009 3:00 PM
		To: sv-ec@server.eda.org
		Cc: 'Mirek Forczek'
		Subject: [sv-ec] random generator state for shallow copy
		
		

		How should below case work? Object ponited by c2 is
created as a shalow copy from object pointed by c1. Then both get
randomized - should values randomized for c1 and c2 be the same?

		class C;
		        rand int i,j;
		        function new;
		                $display("new");
		        endfunction
		        function void post_randomize;
		                $display(i,j);
		        endfunction
		endclass

		module top;
		        C c1,c2;
		        initial begin
		                c1 = new;
		                c1.j.rand_mode(0);
		                c1.randomize();
		                c2 = new c1; //<<<<<<<<<shalow copy
		                c1.randomize(); 
		                c2.randomize(); //should c1.i be equal
c2.i ?????????????
		                c1.randomize();
		                c2.randomize(); //should c1.i be equal
c2.i ??????????????
		        end

		endmodule
		

		 
		 
		DANiel

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