How to pass parameterized class handle as argument

SystemVerilog
, ,
1

//base class as given in the question
class axi_transaction;

typedef enum {WRITE=0, READ=1} rw_e;

rand rw_e rw;
rand bit [31:0] addr, data;

endclass:axi_transaction

//derived class as asked in question
class axi_wr_rd_transaction #(int REPEAT_COUNT=50) extends axi_transaction;

//variable declared to control randomization of rw signal
bit rw_temp;

//variable to monitor loop count for easiness to debug in log file
static int count;

//constraint declaration, will assign value to rw opposite according to rw_temp
constraint limit{if(rw_temp==1) rw==0; else rw==1;}

//pre randomize method to control randomization of addr and data variables according to rw_temp variable
function void pre_randomize();
if(rw_temp==0)
begin
addr.rand_mode(1);
data.rand_mode(1);
end
else
begin
addr.rand_mode(0);
data.rand_mode(0);
end
$write(“Sr.no.=%0d \t rw=%s \t”,++count,rw.name);
endfunction:pre_randomize

//post randomization mathod , will assign rw value to rw_temp variable and display the addr and data.
function void post_randomize();
rw_temp=rw;
$display(" addr=%0d \t data=%0d",addr,data);
//rw.rand_mode(1);
endfunction:post_randomize

//method to generate REPEAT_COUNT number of randomized transaction
function void random(axi_wr_rd_transaction handle);
repeat(REPEAT_COUNT)
begin
void’(handle.randomize());
end
endfunction:random

endclass:axi_wr_rd_transaction

//module declaration
module ei_sv_crv_assign_3_ex_2;

//class instance and handle creation
axi_wr_rd_transaction #(10) axi_tran=new();

initial
begin
$display(“*************************** SIMULATION STARTED “);
void’(axi_tran.random(axi_tran));
$display(”*** SIMULATION ENDED ************************”);
end
endmodule

for the above code , when I passed the parameter value as ‘10’, I am getting below error. help me to solve the problem. I have seen a similar kind of question in this forum but I couldn’t understand the solution.

ERROR:
ncelab: *W, DSEMEL: This SystemVerilog design will be simulated as per IEEE 1800-2009 SystemVerilog simulation semantics. Use -disable_sem2009 option for turning off SV 2009 simulation semantics.
void’(axi_tran.random(axi_tran));
|
ncelab: *E,TYCMPAT (./testbench.sv,64|35): formal and actual do not have assignment compatible data types (expecting datatype compatible with ‘class $unit::axi_wr_rd_transaction#(.REPEAT_COUNT(50))’ but found ‘class $unit::axi_wr_rd_transaction#(.REPEAT_COUNT(10))’ instead).

2

In reply to jishan_bukhari:

I highly recommend removing REPEAT_COUNT as a parameter and making it a member of your transaction class. A parameter should only be used for an item that affects the physical implementation of the interface associated with the agent. Examples would be ADDRESS_WIDTH or DATA_WIDTH. Items that affect the behavior should be a member of the class, since you want the ability to change them on a per-transaction basis.

3

In reply to cgales:

thank you for the response, sir
I understood what you have suggested, but is there any way to fulfill my requirement?

regards.

4

In reply to jishan_bukhari:

As replied by Mr.cgales it’s not recommended to parametrize the class to generate the no.of transactions. In case even if it is parametrized, to call the random method you need not pass the transaction class handle as an argument to randomize the object which is passed as an argument. Instead of it, inside the random method you can use this keyword to refer to the object to be randomized. This will work even the parameter is overridden with different values

module test;
  
class axi_transaction;

  typedef enum {WRITE=0, READ=1} rw_e;

  rand rw_e re;
  rand bit [31:0] addr, data;

endclass:axi_transaction

//derived class as asked in question
class axi_wr_rd_transaction #(int REPEAT_COUNT=50) extends axi_transaction;

  //variable declared to control randomization of rw signal
   bit rw_temp;

  //variable to monitor loop count for easiness to debug in log file
  static int count;

  //constraint declaration, will assign value to rw opposite according to rw_temp
  constraint limit{if(rw_temp==1) rw==0; else rw==1;}

  //pre randomize method to control randomization of addr and data variables according to 
  rw_temp variable
  function void pre_randomize();
    if(rw_temp==0)
      begin
        addr.rand_mode(1);
        data.rand_mode(1);
      end
    else
      begin
        addr.rand_mode(0);
        data.rand_mode(0);
      end
    $write("Sr.no.=%0d \t rw=%s \t",++count,rw.name);
  endfunction:pre_randomize

//post randomization mathod , will assign rw value to rw_temp variable and display the addr and data.
  function void post_randomize();
    rw_temp=rw;
   $display(" addr=%0d \t data=%0d",addr,data);
   //rw.rand_mode(1);
  endfunction:post_randomize

//method to generate REPEAT_COUNT number of randomized transaction
  function void random();
    begin
      repeat(REPEAT_COUNT)
         void'(this.randomize());// this refers to the handle with which the method is called, here it is axi_trans 
    end
  endfunction:random

endclass:axi_wr_rd_transaction

//module declaration
module ei_sv_crv_assign_3_ex_2;

  //class instance and handle creation
  axi_wr_rd_transaction #(10) axi_tran=new();

  initial
    begin
      $display("*************************** SIMULATION STARTED ************************");
      void'(axi_tran.random());
      $display("*************************** SIMULATION ENDED ************************");
    end
endmodule

Regards,
Shanthi

5

In reply to shanthi:

thank you, sir
I understood it now.