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module fillscreen(clk, rst_n, colour, start,
done, vga_x, vga_y, vga_colour, vga_plot);
input logic clk, rst_n, start;
input logic [2:0] colour;
output logic done, vga_plot;
output logic [2:0] vga_colour;
output logic [6:0] vga_y;
output logic [7:0] vga_x;
logic clear;
logic [6:0] y_next;
logic [7:0] x_next;
assign vga_colour = clear ? 3'b000 : vga_x[2:0];
assign vga_plot = clear || (start && ~done);
assign x_next = vga_x + 1;
assign y_next = vga_y + 1;
always_ff @(posedge clk) begin
if (~rst_n) begin
done <= 1'b0;
vga_x <= 8'b0;
vga_y <= 7'b0;
/* Start clearing the screen. */
clear <= 1'b1;
end
if (clear || (start && ~done)) begin
if (vga_y < 120) begin
/* Check for one column less since it takes
* one clock cycle to reset and increment. */
if (vga_x < 159)
vga_x <= x_next;
else begin
vga_x <= 8'b0;
vga_y <= y_next;
end
end else begin
if (clear)
clear <= 1'b0;
else
done <= 1'b1;
vga_x <= 8'b0;
vga_y <= 7'b0;
end
end else if (~start && done)
done <= 1'b0;
end
endmodule: fillscreen
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