Description

In Verdi interactive mode, you can directly add an alive object of the current simulation scope and see the value and the value changes of the members in nWave. Verdi dumps the value to the inter.fsdb file in the background when you try to add it to the waveform. (Where inter.fsdb is the default FSDB file used in interactive mode.)

In Verdi post-processing mode, once dynamic objects are dumped into an FSDB, you can see them in the nWave window, which is Verdi Waveform view.

Following introduce (I) how to dump dynamic objects and (II) how to view them in the nWave window in post-processing mode.

I. Dump Dynamic Objects

• If you are using VCS/Verdi provided UVM library as your base UVM library, following steps help you dump *uvm_pkg*.uvm_component into FSDB:
  

  • Add the following compilation options:
    

    -debug_access+class at least 
    -ntb_opts uvm<version> 
    +define+UVM_VERDI_COMPWAVE

    
    

  • Add the runtime option:
    

    +UVM_VERDI_TRACE=" HIER+COMPWAVE"

Then, all the classes extended from uvm_component (which are often the members of the UVM testbench hierarchy) are dumped to FSDB directly.

• Additionally, two dumping tasks are used to dump objects of class into FSDB and then show them in nWave: $fsdbDumpClassObject and $fsdbDumpvars+class. Based on SV various and flexible coding, $fsdbDumpClassObject uses the class scope (where the class definition is) to dump instanced objects and $fsdbDumpvars+class uses the hierarchy path to dump a variable which datatype is class and belongs to an HDL scope. Note that, unlike HDL signals, dynamic objects often cost more. Thus, more steps and settings tend to remind you to use them carefully.

The following table shows the summary and usage for the two dumping tasks:

The following examples show you how to use the dumping tasks by specifying a class scope or a class variable.

Example 1:
Dumping a UVM component and a UVM sequence using fsdbDumpClassObject

//Use ubus as the example. The following codes are in top-level

`include "ubus_pkg.sv" //includes all ubus uvc for bench structure
…
module ubus_tb_top;
  import uvm_pkg::*;
  import ubus_pkg::*;
  `include "test_lib.sv" //includes all tests and sequence
  …
  initial begin
     run_test();
end
…
endmodule

A. Dumping instanced objects of ubus_master_driver

1. Clarify the scope: The code of ubus_master_driver is in ubus_pkg, which is imported in module ubus_tb_top. The scope is as follows:
   

   "ubus_pkg.ubus_master_driver"; // all instanced objects of ubus_master_driver
   "ubus_pkg.ubus_master_driver@1"; //only ubus_master_driver@1 object

2. Call the dumping task in the initial block of ubus_tb_top module:
   

       initial begin
           $fsdbDumpClassObject("ubus_pkg.ubus_master_driver@1");   
   	end

3. Set environment variable:
   

     > setenv FSDB_ENABLE_EXPAND_CLASS 1

4. Add -debug_access+all compile-time option and perform compilation and simulation

B. Dumping instanced objects of executing sequence, loop_read_modify_write_seq, and see inside <n> level instanced objects

1. Clarify the scope: The code of loop_read_modify_write_seq is included in test_lib.sv, which is included in the module ubus_tb_top. The scope is as follows:
   

   "ubus_tb_top.loop_read_modify_write_seq"

2. Call the dumping task (and specify object_level to 2) in the initial block of the ubus_tb_top module:
   

   initial begin    
   	$fsdbDumpClassObject("ubus_tb_top.loop_read_modify_write_seq",         
   	                                       "+object_level=2"); 
   end

3. Set the environment variable:
   

     > setenv FSDB_ENABLE_EXPAND_CLASS 1

4. Add -debug_access+all compile-time option and perform compilation and simulation
   
   Example 2: Dumping a class variable declared in a module using fsdbDumpvars

//The following codes are in top-level 
module test();   
	import test_pkg::*; //includes the class definition of “generator”   
	
	class foo; 
	… 
	endclass   
	… 
	generator gen_i; 
	foo foo_i; 
	… 
endmodule

Dumping instances gen_i or foo_i are available:

1. Clarify the hierarchy path. The hierarchies are,
   

       "test.gen_i"     
   	"test.foo_i"

2. Call the dumping tasks in the initial block of test module
   

       initial begin
           $fsdbDumpvars("test.gen_i", "+class", "+object_level=1");         
   	       $fsdbDumpvars("test.foo_i", "+class", "+object_level=2");     
   	end

3. Set the environment variables:
   

   	> setenv FSDB_ENABLE_CLASS
     	> setenv FSDB_ENABLE_EXPAND_CLASS 1

4. Add -debug_access+all or -debug_access+class compile-option and perform compilation and simulation
   

II. View Objects in nWave Window

Once the dynamic objects are dumped to the FSDB, you can add and view them in the nWave window.

Before invoking Verdi, set the following environment variable to enable nWave supporting dynamic object features:

setenv VERDI_ENHANCE_DYNAMIC_OBJECT

The following table shows the features that are enabled using the environment variable:

After invoking Verdi (note that in S-2021.09, -lca is required to support VERDI_ENHANCE_DYNAMIC_OBJECT features), open the FSDB and use the following methods to add objects into nWave:

• In the nWave window with opened FSDB file, choose Signal -> Get Signals command to open the "Get Signals" window. Like selecting HDL signals, select the objects you need from the belonged scope in $object_root. For example:
  
  

• In the opened uvm_hier_tree window, select a component that you need and use the RMB -> Add to Waveform
  
  

• After adding one object, you can expand it by double-clicking on it: