Circuits--Sequential --FSM--Serial

1.serial receiver

module top_module(
    input clk,
    input in,
    input reset,
    output done
);

    parameter[3:0] start =4'd0; 
    parameter[3:0] one = 4'd1;
    parameter[3:0] two = 4'd2;
    parameter[3:0] three = 4'd3;
    parameter[3:0] four = 4'd4;
    parameter[3:0] five = 4'd5;
    parameter[3:0] six = 4'd6;
    parameter[3:0] seven = 4'd7;
    parameter[3:0] eight = 4'd8;
    parameter[3:0] stop = 4'd9;
    parameter[3:0] idle = 4'd10;
    parameter[3:0] w = 4'd11;

    reg[3:0] state;
    reg[3:0] next_state;

    always @(*) begin
        case(state)
            start: next_state = one;
            one: next_state = two;
            two: next_state = three;
            three: next_state = four;
            four: next_state = five;
            five: next_state = six;
            six: next_state = seven;
            seven: next_state = eight;
            eight:
                begin
                    if(in)
                        next_state = stop;
                    else
                        next_state = w;
                end
            stop:
                begin
                    if(in)
                        next_state = idle;
                    else
                        next_state = start;
                end
            
            w:
                begin
                    if(in)
                        next_state = idle; 
                    else
                        next_state = w;
                end