A constraint to generate odd_even_odd....... etc sequence

Agrawal_Priyank · June 9, 2017, 4:21am

Hi Ben,

Your code looks perfect but here, user needs to take care toggling of “t1.w” each time after calling randomization. So I teaked your code and modified as below. Please let me know if below code has any side effect,


program blk; 
class test;  
  rand bit [2:0] x;
  // odd_even bit to indicate whether siganl should be odd or even after randomization
  // odd_even == 1 then even data generated
  // odd_even == 0 then odd data generated
  static bit odd_even;
  //pre_randomize function will be called every time before randomize function
  function pre_randomize();
    $display("Inside pre_randomize");
    odd_even = ~odd_even;
  endfunction
  
  constraint cons{
    (odd_even == 1) -> x%2 == 0;
    (odd_even == 0) -> x%2 != 0;
  }
  endclass : test
 
  initial begin
    test t1;
    repeat(10) begin
      t1 = new();
      void'(t1.randomize()); 
      $display ("t1.x = %0d t1.odd_even = %0d", t1.x, t1.odd_even);
    end
  end
 
endprogram

@Omran,
Above code will randomize signal in class itself. Please let me know if it works for you.