update and debug testbench

testbench/half_adder_tb.sv

@@ -0,0 +1,17 @@
+'include "cpu/alu/halfadder.sv"
+
+module halfadder_tb();
+    reg ta,tb;
+    wire t_sum, t_carry;
+    halfadder dut(t_sum, t_carry, ta, tb);
+        initial begin
+            ta = 0; tb = 0;
+            $monitor("A/B: %b, %b ",ta, tb, "S/C: %b, %b",t_sum, t_carry);
+        #5  ta = 1; tb = 0;
+            $monitor("A/B: %b, %b ",ta, tb, "S/C: %b, %b",t_sum, t_carry);
+        #5  ta = 0; tb = 1;
+            $monitor("A/B: %b, %b ",ta, tb, "S/C: %b, %b",t_sum, t_carry);
+        #5  ta = 1; tb = 1;
+            $monitor("A/B: %b, %b ",ta, tb, "S/C: %b, %b",t_sum, t_carry);
+        end
+endmodule