About Constraint

SystemVerilog
1

write a Constraint to generate 5 digit number out of which first two digits is multiple of 7 and last 3 digits could be any thing from 0 to 5

2

In reply to CJRS:
Hi, I hope the following code becomes helpful to you.


class tr;
  rand byte unsigned array[5];
  constraint condition{
    foreach(array[i])
    {
      (i==0) || (i==1) -> (array[i]>0) && (array[i] % 7 == 0);
      (i>1) -> (array[i] inside {[0:5]});
    }
  }
endclass

module test;
  
  tr t=new;
  initial begin
    assert(t.randomize)
      $display("%0p",t.array);
  end
  
endmodule
3

Hi Shubhabrata,

The output of above code is :

'{'hee, 'h5b, 'h2, 'h2, 'h2}
'{'h8c, 'hf5, 'h2, 'h5, 'h1}
'{'h38, 'haf, 'h2, 'h4, 'h3}
'{'h38, 'h2a, 'h2, 'h3, 'h5}
'{'hb6, 'h15, 'h2, 'h0, 'h5}

Here sometimes the last 3 digits have repeated values but it should be unique.(Ex 1st one).
Please Correct me if I am wrong.

Thanks !!!

4

In reply to UVM_geek:

Hi,
I guess that doesn’t matter because the question doesn’t contain any unique elements points. If you want you can add the unique keyword in the constraint .


class tr;
  rand byte unsigned array[5];
  constraint condition{
    foreach(array[i])
    {
      (i==0) || (i==1) -> (array[i]>0) && (array[i] % 7 == 0);
      (i>1) -> (array[i] inside {[0:5]});
    }
  }
      constraint condition2{unique{array};}
endclass
 
module test;
 
  tr t=new;
  initial begin
    repeat(5) begin
    assert(t.randomize)
      $display("%0p",t.array);
  end
  end
 
endmodule
5

Thank you Shubhabrata .