display.v

module display(row, col, red, green, blue, color, up, down, left, right, vnotactive, CLK, RST);
	input [9:0] row, col;
	input CLK, RST, color, up, down, left, right, vnotactive;
	output red, green, blue;
	reg red, green, blue;
	reg [23:0] count, bang;
	reg [9:0] originX, originY, slideY, randX;
	reg [1:0] key_state;
	reg [15:0] state;
	
	function [15:0] Random;
		input [15:0] seed;
		integer value;
		begin
			value = (16'd35245 * state + 16'd1235) % 17'h10000;
			state = value;
			Random = value;
		end
	endfunction
	
	always @(posedge CLK or negedge RST) begin
		if(!RST) begin
			red <= 1'b1;
			green <= 1'b1;
			blue <= 1'b1;
			count <= 24'd0;
			slideY <= 10'd0;
		end else begin
			integer vcol;
				
			if (count == 24'd40000000) begin
				count <= 24'd0;
			end else begin
				count <= count + 24'd1;
			end
			
			if (bang == 24'd0 && !up) begin
				bang = 24'd40000000;
			end
			
			if (bang != 24'd0) begin
				bang = bang - 24'd1;
				
				if (count % 24'd500000 == 24'd0) begin
					integer range;
					range = bang / 24'd400000;
				
					randX = Random(0) % (range * 2) - range;
				end
			end
			
			vcol = (col + randX) % 10'd800;
		
			if ((10'd400 - vcol) * (10'd400 - vcol) + (10'd300 - row) * (10'd300 - row) < 20'd40000) begin
				integer X, cols, rows;
				
				if (count % 24'd500000 == 24'd0) begin
					slideY <= (slideY + 10'd1) % 10'd600;
				end
				
				rows = (row + slideY) % 10'd600;
				cols = (col + rows * rows) % 10'd800;
			
				if (rows % 10'd200 < 10'd100) begin
					X = rows % 10'd100;
				end else begin
					X = 10'd100 - rows % 10'd100;
				end
			
				case (rows / 10'd100)
					3'd0: begin
						red <= 1'b1;
						if (cols % 5'd10 * 5'd10 < X) begin
							green <= 1'b1;
						end else begin
							green <= 1'b0;
						end
						blue <= 1'b0;
					end
					3'd1: begin
						if (cols % 5'd10 * 5'd10 < X) begin
							red <= 1'b1;
						end else begin
							red <= 1'b0;
						end
						green <= 1'b1;
						blue <= 1'b0;
					end
					3'd2: begin
						red <= 1'b0;
						green <= 1'b1;
						if (cols % 5'd10 * 5'd10 < X) begin
							blue <= 1'b1;
						end else begin
							blue <= 1'b0;
						end
					end
					3'd3: begin
						red <= 1'b0;
						if (cols % 5'd10 * 5'd10 < X) begin
							green <= 1'b1;
						end else begin
							green <= 1'b0;
						end
						blue <= 1'b1;
					end
					3'd4: begin
						if (cols % 5'd10 * 5'd10 < X) begin
							red <= 1'b1;
						end else begin
							red <= 1'b0;
						end
						green <= 1'b0;
						blue <= 1'b1;
					end
					3'd5: begin
						red <= 1'b1;
						green <= 1'b0;
						if (cols % 5'd10 * 5'd10 < X) begin
							blue <= 1'b1;
						end else begin
							blue <= 1'b0;
						end
					end
				endcase
			end else begin
				red <= 1'b0;
				green <= 1'b0;
				blue <= 1'b0;
			end
		end
	end
	
	always @(posedge CLK or negedge RST) begin
		if(!RST) begin
			originX <= 10'd300;
			originY <= 10'd200;
			key_state <= 2'd0;
		end
		else begin
			case(key_state)
				2'd0: begin
					if(vnotactive) key_state <= 2'd1;
				end
				2'd1: begin
					if(!up) originY <= originY - 10'd2;
					else if(!down) originY <= originY + 10'd2;
					if(!left) originX <= originX - 10'd2;
					else if(!right) originX <= originX + 10'd2;
					if(!up|!down|!left|!right) key_state <= 2'd2;
					else if(!vnotactive) key_state <= 2'd0;
				end
				2'd2: begin
					if(!vnotactive) key_state <= 2'd0;
				end
				2'd3: begin
				end
			endcase
		end
	end
endmodule