CODEWITHSUNDEEP
uvm
user1978273
user1978273

Reputation: 514

Override sequence members from test

Here is my simple code segment

class sample_sequence extends uvm_sequence#(sample_sequence_item);


rand int no_txn;
  `uvm_object_param_utils_begin(sample_sequence_item)
  `uvm_field_int(no_txn,UVM_ALL_ON)
  `uvm_object_utils_end

  rand sample_sequence_item sample_sequence_item_inst;
  function new(string name="sample_sequence");
    super.new(name);
  endfunction

  virtual task body();
    no_txn = 10;
    for(int i = 0;i<no_trn;i++) begin
      sample_sequence_item_inst = sample_sequence_item::type_id::create($sformatf("sample_sequence_item_%0d",i));
      sample_sequence_item_inst.addr = $urandom_range(0,20);

      start_item(sample_sequence_item_inst);
      finish_item(sample_sequence_item_inst);
    end


  endtask: body

endclass

The sequence just generates random addresses and sends to driver. I want to control the parameter no_txn from the test.

I can do that using the hierarchy for the sequence but is there any UVM based factory method to override it?

Upvotes: 0

Views: 2935

Answers (1)

Tudor Timi
Tudor Timi

Reputation: 7573

I depends on how you start the sequence.

If you start it in the test directly, you can just add a constraint when randomizing the sequence:

class some_test extends uvm_test;
  // ...

  task run_phase(uvm_phase phase);
    sample_sequence seq = sample_seq::type_id::create("seq");
    if (!seq.randomize() with { no_txn == 5; })
      `uvm_fatal("RANDERR", "Randomization error")
    seq.start(sequencer);
  endtask
endclass

If you are extending a test where you started it similarly to what I showed above (minus the with block), then you can create a child class where you add a specific constraint:

class some_other_sequence extends some_sequence;
  constraint do_5_items { no_txn == 5; }
endclass

Somewhere else in your test you'll have to set a type override (I usually do it in the end_of_elaboration_phase(...) function). You can read more about type overrides and the factory in the UVM user guide.

Upvotes: 1

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