fsm 4 locations, move left and right, one hot encoding

fsm_one_hot.v

/* 
 * Do not change Module name 
*/


module FSM(input clk, input [1:0] w, output [3:0]  z);
    localparam A=4'b0001, B=4'b0010, C=4'b0100, D=4'b1000;
    reg [3:0] state, next_state;
    initial state = A;
    always @(posedge clk)
        state <= next_state;
    
    always @(*)
        case (w)
        2'b10: 
            if (state !=A)
                next_state = state >> 1;
        2'b01: 
            if (state !=D)
                next_state = state << 1;
        endcase
    assign z = state;
endmodule


module main;
    reg clk = 0;
    always #1 clk = !clk;

    reg [1:0] in;
    wire [3:0] out;
    FSM fsm(clk, in, out);
  initial 
    begin
      in = 2'b01;
            

      #2 $display("%b",out); in = 2'b10;
            

      #2 $display("%b",out); in = 2'b10;

      #2 $display("%b",out);in = 2'b01;
      
      #2 $display("%b",out);in = 2'b01;
      #2 $display("%b",out);in = 2'b01;
      #2 $display("%b",out);in = 2'b01;
      #2 $display("%b",out);in = 2'b01;

      $finish ;
    end
endmodule