Which way of the randomization is good?

[Prabhu]

Hi

I have a class like this

     class A ;
           int a;
           a dist {1:=10,2:=5,3:=6}
      endclass

which type of randomization would give best distribution of the random values

Type 1:

    A rand_obj;
    for(int count = 0;count <100;count++) begin
        rand_obj = new()
        rand_obj.randomize();
    end        

Type2:

    A rand_obj,rand_obj2;
    rand_obj = new();
    for(int count = 0;count <100;count++) begin
        rand_obj.randomize();
        rand_obj2 = rand_obj.deep_copy();
    end        

My understanding is as follows

Type 2 would give better constraint coverage(meaning distribution) but overriding is a pain

I have two questions

1.Which one is better ?

2.What does the macro `uvm_do implements (Is is the anyone above or some thing else) ?

cheers

Prabhu.G

[dave_59]

If you have a cyclic randc variable (btw you forgot to declare a as rand), only type 2 will work. As far as distributions are concerned, it should not matter. Solutions are produced based on probabilities without considering previous results. Type 2 is also good if you have non-rand state variables that are used in your constraints.

If you mean type 2 is harder to do factory overrides dynamically, yes that is true.