testbench.v

module testbench;
    reg [2:0] in;

	reg patt_out = 0;
	reg patt_carry_out = 0;
	reg patt_out1 = 0;
	reg patt_carry_out1 = 0;
	wire out;
    wire carryout;

    initial begin
        // $dumpfile("testbench.vcd");
        // $dumpvars(0, testbench);

        #5 in = 0;
        repeat (10000) begin
            #5 in = in + 1;
        end

        $display("OKAY");
    end

    top uut (
	.x(in[0]),
	.y(in[1]),
	.cin(in[2]),
	.regA(out),
	.regcout(carryout)
	);

    always @(posedge in[0]) begin
    patt_out1 <=  ~in[1] + &in[2];
    end
    always @(negedge in[0]) begin
        patt_carry_out1 <= in[2] ? |in[1] : patt_out;
    end

    always @(*) begin
        if (in[0])
            patt_out <=  patt_out|in[1]~&in[2];
    end
    always @(*) begin
        if (~in[0])
            patt_carry_out <=  patt_carry_out1&in[2]~|in[1];
    end
	assert_Z out_test(.A(out));

endmodule