hdlbits：Fsm serialdata

module top_module(
    input clk,
    input in,
    input reset,    // Synchronous reset
    output [7:0] out_byte,
    output done
);

parameter IDLE = 4'd0;
parameter BIT0 = 4'd1;
parameter BIT1 = 4'd2;
parameter BIT2 = 4'd3;
parameter BIT3 = 4'd4;
parameter BIT4 = 4'd5;
parameter BIT5 = 4'd6;
parameter BIT6 = 4'd7;
parameter BIT7 = 4'd8;
parameter STOP = 4'd9;
parameter WAIT = 4'd10;

reg [3:0] state,next_state;
reg done_reg = 1'b0;

reg [7:0] temp_out;
always @(*) 
begin
    case(state)
        IDLE:
            begin
                if(in)  next_state <= IDLE;
                else    next_state <= BIT0;
            end
        BIT0,BIT1,BIT2,BIT3,BIT4,BIT5,BIT6,BIT7:
            begin
                next_state <= state + 1'b1;
            end
        STOP:
            if(in)
                next_state <= IDLE;
            else
                next_state <= WAIT;
        WAIT:
            if(in)
                next_state <= IDLE;
            else
                next_state <= WAIT;               
        default:
            next_state <= IDLE;
    endcase
end

always @(posedge clk) 
begin
    if (reset) 
    begin
        state <= IDLE;
    end
    else
    begin
        state <= next_state;
    end
end

always @(posedge clk) 
begin
	case(state)
        BIT0,BIT1,BIT2,BIT3,BIT4,BIT5,BIT6,BIT7:
            begin
                temp_out <= {in,temp_out[7:1]};
				done_reg <= 1'b0;
            end
		STOP:
			begin
				done_reg <= in;
			end
		IDLE,WAIT:
			begin
				done_reg <= 1'b0;
			end
		default:
			begin
				done_reg <= 1'b0;
			end		
	endcase
end

assign done = done_reg;
assign out_byte = temp_out;

endmodule