Array.sum method is not working as expected

SystemVerilog
1

If Change the size of A I am not getting the expected value can anyone help me why I am getting unexpected values


class C;
  rand bit [7:0] A[] ; //if my bit value is 7:0 is getting expected value
constraint c1 { A.size == 5; }
  constraint c2 { A.sum() with (int'(item)) < 1000; }
endclass

module top;
  C A[10];
  initial
    begin
      foreach(A[i])
        begin
          A[i] = new();
          assert(A[i].randomize());
         
          $display(" %p", A[i].A);
            
        end
      
    end
endmodule

run -all

'{52, 116, 27, 117, 9}

'{234, 128, 109, 243, 251}

'{103, 191, 223, 56, 62}

'{1, 143, 120, 157, 215}

'{130, 119, 51, 54, 248}

'{171, 55, 70, 59, 18}

'{134, 194, 18, 241, 91}

'{94, 212, 232, 79, 11}

'{20, 120, 110, 206, 223}

'{227, 253, 171, 58, 124}

exit


class C;
  rand bit [31:0] A[] ;
constraint c1 { A.size == 5; }
  constraint c2 { A.sum() with (int'(item)) < 1000; }
endclass

module top;
  C A[10];
  initial
    begin
      foreach(A[i])
        begin
          A[i] = new();
          assert(A[i].randomize());
         
          $display(" %p", A[i].A);
            
        end
      
    end
endmodule

run -all

'{3787357203, 205694960, 2308197910, 665118826, 4247110087}

'{972731610, 465127672, 2710588818, 3501954850, 3456330263}

'{3020650510, 1576741973, 3787254651, 372673491, 3891600393}

'{2634639171, 62035855, 3195722274, 123205191, 1369482221}

'{3523790041, 2686765230, 13219328, 2036180016, 3200139311}

'{3393038216, 1966423041, 2557274573, 715508048, 3743281444}

'{3428203505, 3012590047, 417466824, 3765525831, 1945975121}

'{390926889, 2541436557, 4244306482, 2478460877, 1509793635}

'{857388233, 2403345028, 3597653875, 1111139865, 3163724970}

'{2533588731, 1202244656, 764513822, 3665321193, 2591416844}

exit

2

In reply to marathuteja:

Your constraint does not handle overflow. Try:

  constraint c2 { A.sum() with (64'(item)) < 1000; }
3

@dave_59
I tried below example but not seeing expected results. Would you help me fix it ?
i expect all items to be within 5 and 10.

class C;
  rand bit [7:0] A[] ; 
constraint c1 { A.size == 5; }
  constraint c2 { A.sum() with (int'(item)) inside {[5:10]}; 
endclass

module top;
  C A[10];
  initial
    begin
      foreach(A[i])
        begin
          A[i] = new();
          assert(A[i].randomize());
         
          $display(" %p", A[i].A);
            
        end
      
    end
endmodule

# run -all
#  '{3, 1, 2, 0, 0}
#  '{4, 2, 0, 3, 1}
#  '{2, 1, 5, 1, 0}
#  '{1, 3, 0, 0, 6}
#  '{4, 0, 0, 1, 1}
#  '{2, 0, 2, 5, 1}
#  '{0, 1, 5, 4, 0}
#  '{2, 2, 0, 4, 2}
#  '{0, 1, 4, 4, 1}
#  '{3, 2, 4, 0, 0}

PS: Sorry I do not the way to format the source code. Im new here, appreciate if you tell me how to format this.

4

Look at this link “format your code” making your code easier for others to read. I have done that for you.

Your constraint makes the sum of the array A to be inside the range 5 to 10. If you want each element of A to be inside that range, then the constraint would be

foreach (A[i]) A[i] inside {[5:10]};
1 Like