rtl/gfx; rewrite scanout

1 files changed, 116 insertions, 0 deletions

diff --git a/rtl/gfx/gfx_scanout_dac.sv b/rtl/gfx/gfx_scanout_dac.sv
new file mode 100644
index 0000000..c8fe218
--- /dev/null
+++ b/rtl/gfx/gfx_scanout_dac.sv
@@ -0,0 +1,116 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_scanout_dac
+(
+	input  logic    clk,
+	                rst_n,
+
+	input  logic    enable_clear,
+	input  rgb24    clear_color,
+
+	input  logic    mask_fifo_out,
+	input  mem_word fb_fifo_out,
+	input  logic    in_valid,
+	output logic    in_ready,
+
+	input  logic    scan_ready,
+	output logic    scan_valid,
+	                scan_endofpacket,
+	                scan_startofpacket,
+	output rgb30    scan_data,
+
+	output logic    vsync
+);
+
+	logic dac_valid, half, half_mask, stall, endofpacket, startofpacket;
+	rgb24 pixel;
+	rgb32 fifo_pixel;
+	mem_word msw, lsw;
+	half_coord next_addr;
+	linear_coord max_addr, pixel_addr;
+
+	struct packed
+	{
+		logic endofpacket,
+		      startofpacket;
+		rgb30 pixel;
+	} skid_in, skid_out;
+
+	assign scan_data = skid_out.pixel;
+	assign scan_endofpacket = skid_out.endofpacket;
+	assign scan_startofpacket = skid_out.startofpacket;
+
+	assign max_addr = `GFX_X_RES * `GFX_Y_RES - 1;
+
+	function color10 dac_color(color8 in);
+		dac_color = {in, {2{in[0]}}};
+	endfunction
+
+	assign fifo_pixel = {msw, lsw};
+	assign skid_in.pixel.r = dac_color(pixel.r);
+	assign skid_in.pixel.g = dac_color(pixel.g);
+	assign skid_in.pixel.b = dac_color(pixel.b);
+	assign skid_in.endofpacket = endofpacket;
+	assign skid_in.startofpacket = startofpacket;
+
+	always_comb begin
+		// Descarta fifo_pixel.a
+		pixel.r = fifo_pixel.r;
+		pixel.g = fifo_pixel.g;
+		pixel.b = fifo_pixel.b;
+
+		if (!half_mask)
+			pixel = clear_color;
+	end
+
+	gfx_skid_flow flow
+	(
+		.in_valid(dac_valid),
+		.out_ready(scan_ready),
+		.out_valid(scan_valid),
+		.*
+	);
+
+	gfx_skid_buf #(.WIDTH($bits(skid_in))) skid
+	(
+		.in(skid_in),
+		.out(skid_out),
+		.*
+	);
+
+	always_ff @(posedge clk or negedge rst_n)
+		if (!rst_n) begin
+			half <= 0;
+			vsync <= 0;
+			dac_valid <= 0;
+			pixel_addr <= 0;
+		end else begin
+			vsync <= 0;
+			if (in_ready && dac_valid) begin
+				vsync <= scan_endofpacket;
+				dac_valid <= 0;
+			end
+
+			if (in_ready && in_valid) begin
+				half <= !half;
+				dac_valid <= half;
+
+				if (half) begin
+					pixel_addr <= pixel_addr + 1;
+					if (pixel_addr == max_addr)
+						pixel_addr <= 0;
+				end
+			end
+		end
+
+	always_ff @(posedge clk)
+		if (in_ready && in_valid) begin
+			lsw <= msw;
+			msw <= fb_fifo_out;
+			half_mask <= mask_fifo_out;
+
+			endofpacket <= pixel_addr == max_addr;
+			startofpacket <= pixel_addr == 0;
+		end
+
+endmodule