2D array constraint randomization

SystemVerilog
,
5

I tried a different approach that involves matrix transpose. I basically tried to solve the magic square problem (including the constraints on both the diagonals as well). Hope that helps!


class magic_square#(int grid_size=4);
  rand bit[4:0] rand_array[grid_size][grid_size];
  rand bit[4:0] rand_array_transpose[grid_size][grid_size];
  rand bit[4:0] diagonal_0[grid_size];
  rand bit[4:0] diagonal_1[grid_size];
  rand int unsigned rand_sum;
 
  constraint magic_square_cnstr {
    rand_sum >= 0;
    rand_sum <= 8'hFF;
 
    foreach(rand_array[i]) {
      unique{rand_array[i]};
      rand_array[i].sum() with (int'(item)) == rand_sum;
    }
 
    foreach(rand_array[i,j]) {
      rand_array_transpose[j][i] == rand_array[i][j];
      if (i==j) {
        diagonal_0[i] == rand_array[i][j];
      }
      if ((i+j) == grid_size-1) {
        diagonal_1[i] == rand_array[i][j];
      }
    }
 
    foreach(rand_array_transpose[i]) {
      unique{rand_array_transpose[i]};
      rand_array_transpose[i].sum() with (int'(item)) == rand_sum;
    }
 
    foreach(rand_array[i,j]) {
      foreach(rand_array[i1,j1]) {
        if ((i!=i1) && (j!=j1)) {
          rand_array[i][j] != rand_array[i1][j1];
        }
      }
    }
    diagonal_0.sum() with (int'(item)) == rand_sum;
    diagonal_1.sum() with (int'(item)) == rand_sum;                            
  }
 
  function post_randomize();
    string row_print;
    $display("Solving for grid_size:0x%0x sum:0x%0x", grid_size, rand_sum);
    foreach (rand_array[row]) begin
      row_print = {row_print,$sformatf("%p \n", rand_array[row])};
    end
    $display ("%s", row_print);
  endfunction // post_randomize
 
  endclass // magic_square
 
module magic_square();
 
initial begin
  magic_square #(4) ms = new();
  assert(ms.randomize());
 
end
 
endmodule // magic_square