adds simple tb to verify ksa adder

tb/simple_tb.sv

@@ -0,0 +1,81 @@
+parameter WIDTH = `WIDTH;
+parameter NUM_PKT = 50;
+`timescale 1ns/1ns
+//`include "ksa_adder.v"
+
+module tb;
+    reg [WIDTH-1:0]     a, b;
+    reg                 cin;
+    wire [WIDTH-1:0]    sum;
+    wire                cout;
+
+    ksa_adder #(WIDTH) dut(
+        .a(a),
+        .b(b),
+        .cin(cin),
+        .sum(sum),
+        .cout(cout)
+    );
+
+    bit [31:0] a1, b1;
+    bit cin1;
+    event start_check;
+
+    class transaction;
+        rand bit [31:0] a, b;
+        rand bit cin;
+        bit [32:0] ideal_sum;
+        bit [31:0] sum;
+        bit cout;
+
+        constraint cin_val {
+            cin dist {0:=60, 1:=40};
+        } 
+
+        function void printf();
+            $display("Driven packet -> a = %0h, b = %0h, cin = %0b", a, b, cin);
+        endfunction
+
+        function void check();
+            ideal_sum = a + b + cin;
+            if(sum == ideal_sum[31:0] && cout == ideal_sum[32]) begin
+                $display("*** Output matched *** \nExpected: sum = %0h, cout = %0b; Actual sum = %0h, cout = %0b\n",ideal_sum[31:0], ideal_sum[32], sum, cout);
+            end
+            else begin
+                if(sum != ideal_sum[31:0]) begin
+                    $error("*** Sum is not matching*** \nExpected: sum = %0h, cout = %0b; Actual sum = %0h, cout = %0b\n",ideal_sum[31:0], ideal_sum[32], sum, cout);
+                end
+                else if(cout != ideal_sum[32]) begin
+                    $error("*** Cout is not matching*** \nExpected: sum = %0h, cout = %0b; Actual sum = %0h, cout = %0b\n",ideal_sum[31:0], ideal_sum[32], sum, cout);
+                end
+            end
+        endfunction
+    endclass //transaction
+
+    transaction tr;
+
+    initial begin: driver
+        #10;
+        tr = new();
+        repeat(NUM_PKT) begin
+            tr.randomize();
+            a <= tr.a;
+            b <= tr.b;
+            cin <= tr.cin;
+            tr.printf();
+            ->start_check;
+            #40;
+        end
+        $finish();
+    end
+
+    initial begin: scoreboard
+        forever begin
+            @(start_check);
+            #2;
+            tr.sum = sum;
+            tr.cout = cout;
+            tr.check();
+        end
+    end
+endmodule