localparam [4 : 0] STATE_START          = 4'd0;
    localparam [4 : 0] STATE_DECREMENT_WAIT = 4'd1;
    localparam [4 : 0] STATE_DECREMENT_0    = 4'd2;
    localparam [4 : 0] STATE_DECREMENT_1    = 4'd3;
    localparam [4 : 0] STATE_DECREMENT_2    = 4'd4;
    localparam [4 : 0] STATE_INCREMENT_WAIT = 4'd5;
    localparam [4 : 0] STATE_INCREMENT_0    = 4'd6;
    localparam [4 : 0] STATE_INCREMENT_1    = 4'd7;
    localparam [4 : 0] STATE_INCREMENT_2    = 4'd8;
    localparam [4 : 0] STATE_STOP           = 4'd9;

    reg [4 : 0] state_int;
    assign state_out = state_int;

    always @(posedge gtwiz_userclk_tx_usrclk_in)
    begin
        if(hb_gtwiz_reset_all_sync == 1'b1)
        begin
            state_int <= STATE_START;
        end
        else
        begin
            case(state_int)
                STATE_START:
                    begin
                        if(init_done_in == 1'b1)
                            state_int <= STATE_DECREMENT_WAIT;
                        else
                            state_int <= STATE_START;
                    end
                STATE_DECREMENT_WAIT:
                    begin
                        // TX FIFO is less than half full
                        if(txbufstatus_in[0] == 1'b0)
                            state_int <= STATE_INCREMENT_WAIT;
                        // TX FIFO is at least half full
                        else
                            state_int <= STATE_DECREMENT_0;
                    end
                STATE_DECREMENT_0:
                    begin
                        state_int <= STATE_DECREMENT_1;
                    end
                STATE_DECREMENT_1:
                    begin
                        state_int <= STATE_INCREMENT_2;
                    end
                STATE_DECREMENT_2:
                    begin
                        state_int <= STATE_DECREMENT_WAIT;
                    end
                STATE_INCREMENT_WAIT:
                    begin
                        // TX FIFO is less than half full
                        if(txbufstatus_in[0] == 1'b0)
                            state_int <= STATE_INCREMENT_0;
                        // TX FIFO is at least half full
                        else
                            state_int <= STATE_STOP;
                    end
                STATE_INCREMENT_0:
                    begin
                        state_int <= STATE_INCREMENT_1;
                    end
                STATE_INCREMENT_1:
                    begin
                        state_int <= STATE_INCREMENT_2;
                    end
                STATE_INCREMENT_2:
                    begin
                        state_int <= STATE_INCREMENT_WAIT;
                    end
                STATE_STOP:
                    begin
                        state_int <= STATE_STOP;
                    end
                default:
                    begin
                        state_int <= STATE_START;
                    end
            endcase
        end
    end

    always @(state_int)
    begin
        case(state_int)
            STATE_START:
                begin
                    txpippmen_out       <= 1'b0;
                    txpippmstepsize_out <= 5'b00000;
                    init_done_out       <= 1'b0;
                end
            STATE_DECREMENT_WAIT:
                begin
                    txpippmen_out       <= 1'b0;
                    txpippmstepsize_out <= 5'b00001;
                    init_done_out       <= 1'b0;
                end
            STATE_DECREMENT_0:
                begin
                    txpippmen_out       <= 1'b1;
                    txpippmstepsize_out <= 5'b00001;
                    init_done_out       <= 1'b0;
                end
            STATE_DECREMENT_1:
                begin
                    txpippmen_out       <= 1'b1;
                    txpippmstepsize_out <= 5'b00001;
                    init_done_out       <= 1'b0;
                end
            STATE_DECREMENT_2:
                begin
                    txpippmen_out       <= 1'b0;
                    txpippmstepsize_out <= 5'b00001;
                    init_done_out       <= 1'b0;
                end
            STATE_INCREMENT_WAIT:
                begin
                    txpippmen_out       <= 1'b0;
                    txpippmstepsize_out <= 5'b10001;
                    init_done_out       <= 1'b0;
                end
            STATE_INCREMENT_0:
                begin
                    txpippmen_out       <= 1'b1;
                    txpippmstepsize_out <= 5'b10001;
                    init_done_out       <= 1'b0;
                end
            STATE_INCREMENT_1:
                begin
                    txpippmen_out       <= 1'b1;
                    txpippmstepsize_out <= 5'b10001;
                    init_done_out       <= 1'b0;
                end
            STATE_INCREMENT_2:
                begin
                    txpippmen_out       <= 1'b0;
                    txpippmstepsize_out <= 5'b10001;
                    init_done_out       <= 1'b0;
                end
            STATE_STOP:
                begin
                    txpippmen_out       <= 1'b0;
                    txpippmstepsize_out <= 5'b00000;
                    init_done_out       <= 1'b1;
                end
        endcase
    end