`timescale 1ps / 1ps

module display(
	input wire nreset,
	input wire clk,
	input wire [5:0] red,   //
	input wire [5:0] green, // current pixel
	input wire [5:0] blue,  //
	output wire [7:0] x, // current pixel x
	output wire [7:0] y, // current pixel y
	output wire frame, // new frame indicator
	output wire pixel, // new pixel indicator
	output wire sck,
	output wire cs,
	output wire mosi,
	output wire dc
);

localparam STATE_INIT_WAIT = 0;
localparam STATE_INIT_RESET = 1;
localparam STATE_INIT_WAIT_AFTER_RESET = 2;
localparam STATE_INIT_STOP_SLEEP = 3;
localparam STATE_INIT_WAIT_AFTER_STOP_SLEEP = 4;
localparam STATE_INIT_SET_FORMAT = 5;
localparam STATE_INIT_SET_FORMAT_PARAM1 = 6;
localparam STATE_INIT_WAIT_AFTER_SET_FORMAT = 7;
localparam STATE_INIT_SET_COLUMN_ADDRESS_RANGE = 8;
localparam STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM1 = 9;
localparam STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM2 = 10;
localparam STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM3 = 11;
localparam STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM4 = 12;
localparam STATE_INIT_SET_ROW_ADDRESS_RANGE = 13;
localparam STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM1 = 14;
localparam STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM2 = 15;
localparam STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM3 = 16;
localparam STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM4 = 17;
localparam STATE_INIT_SET_ADDRESSING_MODE = 18;
localparam STATE_INIT_SET_ADDRESSING_MODE_PARAM1 = 19;
localparam STATE_INIT_SET_DISPLAY_INVERSION = 20;
localparam STATE_INIT_SET_DISPLAY_MODE = 21;
localparam STATE_INIT_WAIT_AFTER_SET_DISPLAY_MODE = 22;
localparam STATE_INIT_TURN_ON_DISPLAY = 23;
localparam STATE_INIT_WAIT_AFTER_TURN_ON_DISPLAY = 24;
localparam STATE_SEND_DISPLAY_CONTENTS_COMMAND = 25;
localparam STATE_SEND_DISPLAY_CONTENTS_RED = 26;
localparam STATE_SEND_DISPLAY_CONTENTS_GREEN = 27;
localparam STATE_SEND_DISPLAY_CONTENTS_BLUE = 28;

wire next;

logic [7:0] spi_data_r;
logic send_data_r;
logic dc_r;

logic [20:0] wait_counter_r;

logic [4:0] state;

logic [7:0] x_r;
logic [7:0] y_r;

logic frame_r;
logic pixel_r;

spi spi_inst(
	.nreset(nreset),
	.clk(clk),
	.data(spi_data_r),
	.send_data(send_data_r),
	.sck(sck),
	.mosi(mosi),
	.next(next)
);

always_ff @(posedge clk) begin
	if (nreset) begin
		send_data_r <= 0;
		frame_r <= 0;
		pixel_r <= 0;

		case (state)
			STATE_INIT_WAIT : begin
				wait_counter_r <= wait_counter_r - 1;

				if (wait_counter_r == 0) begin
					wait_counter_r <= 0;
					state <= STATE_INIT_RESET;
				end
			end

			STATE_INIT_RESET : begin
				send_data_r <= 1;
				dc_r <= 0;
				spi_data_r <= 8'h01;

				if (next) begin
					wait_counter_r <= 150000 * 48; // 150 ms wait
					state <= STATE_INIT_WAIT_AFTER_RESET;
				end
			end

			STATE_INIT_WAIT_AFTER_RESET : begin
				wait_counter_r <= wait_counter_r - 1;

				if (wait_counter_r == 0) begin
					wait_counter_r <= 0;
					state <= STATE_INIT_STOP_SLEEP;
				end
			end

			STATE_INIT_STOP_SLEEP : begin
				send_data_r <= 1;
				dc_r <= 0;
				spi_data_r <= 8'h11;

				if (next) begin
					wait_counter_r <= 10000 * 48; // 10 ms wait
					state <= STATE_INIT_WAIT_AFTER_STOP_SLEEP;
				end
			end

			STATE_INIT_WAIT_AFTER_STOP_SLEEP : begin
				wait_counter_r <= wait_counter_r - 1;

				if (wait_counter_r == 0) begin
					wait_counter_r <= 0;

					state <= STATE_INIT_SET_FORMAT;
				end
			end

			STATE_INIT_SET_FORMAT : begin
				send_data_r <= 1;
				dc_r <= 0;
					spi_data_r <= 8'h3A;

					if (next) begin
						state <= STATE_INIT_SET_FORMAT_PARAM1;
					end
				end

				STATE_INIT_SET_FORMAT_PARAM1 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h06;

					if (next) begin
						state <= STATE_INIT_WAIT_AFTER_SET_FORMAT;
						wait_counter_r <= 10000 * 48; // 10ms wait
					end
				end

				STATE_INIT_WAIT_AFTER_SET_FORMAT : begin
					wait_counter_r <= wait_counter_r - 1;

					if (wait_counter_r == 0) begin
						wait_counter_r <= 0;

						state <= STATE_INIT_SET_COLUMN_ADDRESS_RANGE;
					end
				end

				STATE_INIT_SET_COLUMN_ADDRESS_RANGE : begin
					send_data_r <= 1;
					dc_r <= 0;
					spi_data_r <= 8'h2A;

					if (next) begin
						state <= STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM1;
					end
				end
				
				STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM1 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h00;

					if (next) begin
						state <= STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM2;
					end
				end

				STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM2 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h35;

					if (next) begin
						state <= STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM3;
					end
				end

				STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM3 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h00;

					if (next) begin
						state <= STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM4;
					end
				end

				STATE_INIT_SET_COLUMN_ADDRESS_RANGE_PARAM4 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'hBB;

					if (next) begin
						state <= STATE_INIT_SET_ROW_ADDRESS_RANGE;
					end
				end

				STATE_INIT_SET_ROW_ADDRESS_RANGE : begin
					send_data_r <= 1;
					dc_r <= 0;
					spi_data_r <= 8'h2B;

					if (next) begin
						state <= STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM1;
					end
				end

				STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM1 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h00;

					if (next) begin
						state <= STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM2;
					end
				end

				STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM2 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h28;

					if (next) begin
						state <= STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM3;
					end
				end

				STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM3 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h01;

					if (next) begin
						state <= STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM4;
					end
				end

				STATE_INIT_SET_ROW_ADDRESS_RANGE_PARAM4 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'h17;

					if (next) begin
						state <= STATE_INIT_SET_ADDRESSING_MODE;
					end
				end

				STATE_INIT_SET_ADDRESSING_MODE : begin
					send_data_r <= 1;
					dc_r <= 0;
					spi_data_r <= 8'h36;

					if (next) begin
						state <= STATE_INIT_SET_ADDRESSING_MODE_PARAM1;
					end
				end

				STATE_INIT_SET_ADDRESSING_MODE_PARAM1 : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= 8'hC0;

					if (next) begin
						state <= STATE_INIT_SET_DISPLAY_INVERSION;
					end
				end

				STATE_INIT_SET_DISPLAY_INVERSION : begin
					send_data_r <= 1;
					dc_r <= 0;
					spi_data_r <= 8'h21;

					if (next) begin
						state <= STATE_INIT_SET_DISPLAY_MODE;
					end
				end

				STATE_INIT_SET_DISPLAY_MODE : begin
					send_data_r <= 1;
					dc_r <= 0;
					spi_data_r <= 8'h13;

					if (next) begin
						wait_counter_r <= 10000 * 48; // 10ms wait
						state <= STATE_INIT_WAIT_AFTER_SET_DISPLAY_MODE;
					end
				end

				STATE_INIT_WAIT_AFTER_SET_DISPLAY_MODE : begin
					wait_counter_r <= wait_counter_r - 1;

					if (wait_counter_r == 0) begin
						wait_counter_r <= 0;

						state <= STATE_INIT_TURN_ON_DISPLAY;
					end
				end

				STATE_INIT_TURN_ON_DISPLAY : begin
					send_data_r <= 1;
					dc_r <= 0;
					spi_data_r <= 8'h29;

					if (next) begin
						wait_counter_r <= 10000 * 48; // 10ms wait
						state <= STATE_INIT_WAIT_AFTER_TURN_ON_DISPLAY;
					end
				end

				STATE_INIT_WAIT_AFTER_TURN_ON_DISPLAY : begin
					wait_counter_r <= wait_counter_r - 1;

					if (wait_counter_r == 0) begin
						wait_counter_r <= 0;

						state <= STATE_SEND_DISPLAY_CONTENTS_COMMAND;
					end
				end

				STATE_SEND_DISPLAY_CONTENTS_COMMAND : begin
					send_data_r <= 1;
					dc_r <= 0;
					spi_data_r <= 8'h2C;

					if (next) begin
						x_r <= 0;
						y_r <= 0;
						wait_counter_r <= 32400; // 240 * 135
						state <= STATE_SEND_DISPLAY_CONTENTS_RED;
					end
				end

				STATE_SEND_DISPLAY_CONTENTS_RED : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= {red, 2'b00};

					if (next) begin
						state <= STATE_SEND_DISPLAY_CONTENTS_GREEN;
					end
				end

				STATE_SEND_DISPLAY_CONTENTS_GREEN : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= {green, 2'b00};

					if (next) begin
						state <= STATE_SEND_DISPLAY_CONTENTS_BLUE;
					end
				end

				STATE_SEND_DISPLAY_CONTENTS_BLUE : begin
					send_data_r <= 1;
					dc_r <= 1;
					spi_data_r <= {blue, 2'b00};

					if (next) begin
						x_r <= x_r + 1;
						if (x_r == 134) begin
							x_r <= 0;
							y_r <= y_r + 1;
						end
						wait_counter_r <= wait_counter_r - 1;
						if (wait_counter_r == 1) begin
							frame_r <= 1;
							state <= STATE_SEND_DISPLAY_CONTENTS_COMMAND;
						end else begin
							pixel_r <= 1;
							state <= STATE_SEND_DISPLAY_CONTENTS_RED;
						end
					end
				end
		endcase
	end else begin
			spi_data_r <= 0;
		send_data_r <= 0;
		wait_counter_r <= 10;
		dc_r <= 0;
		state <= STATE_INIT_WAIT;
		x_r <= 0;
		y_r <= 0;
		frame_r <= 0;
		pixel_r <= 0;
	end
end

assign cs = ~send_data_r;
assign dc = dc_r;
assign x = x_r;
assign y = y_r;
assign frame = frame_r;
assign pixel = pixel_r;

endmodule