UVM randomization dilemma

UVM
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2

In reply to salmanepos:

array[0].type == TYPE_A;
array[1].type == TYPE_B;
others TYPEA or B;
How do i randomize the balanced or unbalanced brackets across the whole array? Thanks

This is pretty easy to randomize:


class instruction_stream;
  rand instruction instrs[];

  constraint num_of_instrs {
    instrs.size() <= 10;
  }

  constraint first_two_instrs {
    instrs[0].type == TYPE_A;
    instrs[1].type == TYPE_B;
  }
endclass

Since randomization can’t create objects, you’ll need to make sure you have enough already constructed objects in the array. This way, a call to randomize() can just throw away the objects it doesn’t need:



function void pre_randomize();
  instrs = new[10];  // magic number '10' could a constant defined somwhere else
  foreach (instrs*)
    instrs[i] = new();
endfunction

I prefer doing the pre-allocation in [i]pre_randomize()*, because this way it always gets done before any call to randomize(). This way, it’s not problem if you create a single stream and randomize it multiple times.

For your instruction interdependencies (the “brackets”), you’ll need to be a bit more specific, since it’s not really clear what you intend to constrain.