Unique array method

SystemVerilog
1

Hi,

Does the array method unique returns the unique value in the array or does it do both returning the unique values and sort them in ascending order ?

Code snippet :

module top;
 	initial
	begin
 	int f[8] = {9,2,5,8,5,7,2,9};
	int d[] = {1,9,12,16};
	int q[$] = {2,31,5,14};
	int tq[$];
	tq = f.unique();
	$display("%p",tq);
        end
endmodule

I see that in the o/p sorting is happening. Please let me know that cause for it.

2

The “unique” method just returns all the unique elements. It does not perform a sort implicitly. You can invoke sort explicitly to sort the array in ascending order.

The following code works fine on EDAPlayground with VCS 2014.

module top;
 	initial
	begin
 	int f[8] = {9,2,5,8,5,7,2,9};
	int d[] = {1,9,12,16};
	int q[$] = {2,31,5,14};
	int tq[$];
    int tq1[$];
	tq = f.unique();
	$display("%p",tq);
      tq.sort();
      $display("%p",tq);
        end
endmodule

// output
'{9, 2, 5, 8, 7} 
'{2, 5, 7, 8, 9}
3

In reply to Ravi007:

The LRM does not define the ordering returned by unique(). Some algorithms are more efficient when the elements are sorted first, but you can’t count on it.