UVM Questasim simulation

HI ,

I am trying to simulate a generic ALU in Systemverilog UVM test environment . My add_i is random input signal , but when i open my wave i dont see it toggling , but the display function reports it is being toggled ?

here are my files :

// alu package file //

package alu_pkg;

//----Transaction Class----

class transaction;

//declaring the transaction items

rand bit [3:0] a;

rand bit [3:0] b;

bit [6:0] c;

rand bit add_i;

function void display(string name);

$display("-------------------------");

$display("- %s ",name);

$display("-------------------------");

$display("- a = %0d, b = %0d",a,b);

$display("- c = %0d",c);

$display("-------------------------");

$display("-- ADD = %b --",add_i);

endfunction

endclass

//---------------------------------------//

//-----------Driver Class------------------

class driver;

//used to count the number of transactions

int no_transactions;

//creating virtual interface handle

virtual intf_alu#(.WORD_LENGTH(4)) vif;

//creating mailbox handle

mailbox gen2driv;

//constructor

function new(virtual intf_alu vif,mailbox gen2driv);

//getting the interface

this.vif = vif;

//getting the mailbox handles from environment

this.gen2driv = gen2driv;

endfunction

//Reset task, Reset the Interface signals to default/initial values

task reset;

wait(vif.reset);

$display("[ DRIVER ] ----- Reset Started -----");

vif.a <= 0;

vif.b <= 0;

vif.valid <= 0;

vif.add_i <= 0;

vif.mul_i <= 0;

vif.sub_i <= 0;

vif.div_i <= 0;

vif.and_i <= 0;

vif.or_i <= 0;

vif.xor_i <= 0;

wait(!vif.reset);

$display("[ DRIVER ] ----- Reset Ended -----");

endtask

//drivers the transaction items to interface signals

task main;

forever begin

transaction trans;

gen2driv.get(trans);

@(posedge vif.clk);

vif.valid <= 1;

//vif.add_i <= 1;

vif.a <= trans.a;

vif.b <= trans.b;

@(posedge vif.clk);

vif.valid <= 0;

//vif.add_i <= 0;

trans.c = vif.c;

@(posedge vif.clk);

trans.display("[ Driver ]");

no_transactions++;

end

endtask

endclass

//---------------------------------------//

//----Generator Class------------------

class generator;

//declaring transaction class

rand transaction trans;

//repeat count, to specify number of items to generate

int repeat_count;

//mailbox, to generate and send the packet to driver

mailbox gen2driv;

//event, to indicate the end of transaction generation

event ended;

//constructor

function new(mailbox gen2driv);

//getting the mailbox handle from env, in order to share the transaction packet between the generator and driver, the same mailbox is shared between both.

this.gen2driv = gen2driv;

endfunction

//main task, generates(create and randomizes) the repeat_count number of transaction packets and puts into mailbox

task main();

repeat(repeat_count) begin

trans = new();

if( !trans.randomize() ) $fatal("Gen:: trans randomization failed");

trans.display("[ Generator ]");

gen2driv.put(trans);

end

-> ended; //triggering indicatesthe end of generation

endtask

endclass

//---------------------------------------//

//----Environment Class------------------

class environment;

//generator and driver instance

generator gen;

driver driv;

//mailbox handle's

mailbox gen2driv;

//virtual interface

virtual intf_alu#(.WORD_LENGTH(4)) vif;

//constructor

function new(virtual intf_alu vif);

//get the interface from test

this.vif = vif;

//creating the mailbox (Same handle will be shared across generator and driver)

gen2driv = new();

//creating generator and driver

gen = new(gen2driv);

driv = new(vif,gen2driv);

endfunction

//

task pre_test();

driv.reset();

endtask

task test();

fork

gen.main();

driv.main();

join_any

endtask

task post_test();

wait(gen.ended.triggered);

wait(gen.repeat_count == driv.no_transactions);

endtask

//run task

task run;

pre_test();

test();

post_test();

$finish;

endtask

endclass

//---------------------------------------//

endpackage