Polished

Author: greg-stitt-uf

combinational/alu_tb.sv

@@ -11,8 +11,8 @@ module alu_tb;
    localparam NUM_TESTS = 10000;   
    localparam WIDTH = 8;   
    logic [WIDTH-1:0] in0, in1, out;
-   logic [1:0] 	     sel;
-   logic 	     neg, pos, zero;
+   logic [1:0]       sel;
+   logic             neg, pos, zero;
    logic [WIDTH-1:0] correct_out;
 
    alu #(.WIDTH(WIDTH)) DUT (.*);
@@ -21,37 +21,37 @@ module alu_tb;
    function void check_flags();
       // Check negative flag.
       if (correct_out[WIDTH-1] != neg)
-	$display("ERROR (time %0t): neg = %b instead of %b.", $realtime, neg, correct_out[WIDTH-1]);
+        $display("ERROR (time %0t): neg = %b instead of %b.", $realtime, neg, correct_out[WIDTH-1]);
 
       // Check zero flag.
       if ((correct_out == 0) != zero)
-	$display("ERROR (time %0t): zero = %b instead of %b.", $realtime, zero, correct_out == 0);
+        $display("ERROR (time %0t): zero = %b instead of %b.", $realtime, zero, correct_out == 0);
 
       // Check pos flag.
-      if (((correct_out != 0) && !correct_out[WIDTH-1]) != pos)
-	$display("ERROR (time %0t): pos = %b instead of %b.", $realtime, pos, correct_out != 0 && !correct_out[WIDTH-1]);      
+      if ((signed'(correct_out) > 0) != pos)
+        $display("ERROR (time %0t): pos = %b instead of %b.", $realtime, pos, correct_out != 0 && !correct_out[WIDTH-1]);      
    endfunction
 
    initial begin
       $timeformat(-9, 0, " ns");
 
       // Test NUM_TESTS random inputs and select values.
       for (int i=0; i < NUM_TESTS; i++) begin
-	 in0 = $random;
-	 in1 = $random;
-	 sel = $random;	 
-	 #10;	 
-	 if (sel == 2'b00) correct_out = in0 + in1;
-	 else if (sel == 2'b01) correct_out = in0 - in1;
-	 else if (sel == 2'b10) correct_out = in0 & in1;
-	 else if (sel == 2'b11) correct_out = in0 | in1;
-
-	 if (out != correct_out)
-	      $display("ERROR (time %0t): out = %h instead of %h.", $realtime, out, correct_out);
-
-	 if (sel == 2'b00 || sel == 2'b01) check_flags();	 
+         in0 = $random;
+         in1 = $random;
+         sel = $random;  
+         #10;    
+         if (sel == 2'b00) correct_out = in0 + in1;
+         else if (sel == 2'b01) correct_out = in0 - in1;
+         else if (sel == 2'b10) correct_out = in0 & in1;
+         else if (sel == 2'b11) correct_out = in0 | in1;
+
+         if (out != correct_out)
+              $display("ERROR (time %0t): out = %h instead of %h.", $realtime, out, correct_out);
+
+         if (sel == 2'b00 || sel == 2'b01) check_flags();        
       end 
 
       $display("Tests completed.");      
-   end	         
+   end           
 endmodule