module tb1hc; // random unsigned inputs, decimal values including a check

reg  [7:0] a, b;  // 8-bit inputs (to be chosen randomly)
reg  c0;          // carry input  (to be chosen randomly)
wire [7:0] s;     // 8-bit sum output
wire c8;          // carry out of the MSB position
reg  [8:0] check; // 9-bit sum value used to check correctess

// instantiate the 8-bit Han-Carlson adder
han_carlson hc1(a, b, c0, s, c8);

// simulation of 50 random addition operations
initial repeat (50) begin
    // get new operand values and compute a check value
    a = $random; b = $random; c0 = $random;
    check = a + b + c0;

    // compute and display the sum every 10 time units
    #10 $display($time, "  %d + %d + %d = %d (%d)", a, b, c0, {c8, s}, check);
end

endmodule