From 6fb3849e73b797d4610a2b782127f927dec0c9c9 Mon Sep 17 00:00:00 2001
From: Alejandro Soto <alejandro@34project.org>
Date: Mon, 14 Nov 2022 21:10:40 -0600
Subject: Implement VGA simulation

---
 tb/vga.hpp | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 tb/vga.hpp

(limited to 'tb/vga.hpp')

diff --git a/tb/vga.hpp b/tb/vga.hpp
new file mode 100644
index 0000000..92446ca
--- /dev/null
+++ b/tb/vga.hpp
@@ -0,0 +1,72 @@
+#ifndef LIBTALLER_VGA_HPP
+#define LIBTALLER_VGA_HPP
+
+#include <array>
+#include <cstddef>
+#include <cstdint>
+
+#include <SDL2/SDL_surface.h>
+#include <SDL2/SDL_video.h>
+
+namespace taller::vga
+{
+	struct timings
+	{
+		unsigned active;
+		unsigned front_porch;
+		unsigned sync;
+		unsigned back_porch;
+	};
+
+	struct video_mode
+	{
+		std::uint32_t pixel_clk;
+		timings       h;
+		timings       v;
+	};
+
+	template<class Crtc>
+	class display
+	{
+		public:
+			display(Crtc &crtc, std::uint32_t clock_hz) noexcept;
+
+			~display() noexcept;
+
+			void tick(bool clk) noexcept;
+
+			inline bool key(std::size_t index)
+			{
+				return keys.at(index);
+			}
+
+		private:
+			Crtc&               crtc;
+			SDL_Window         *window     = nullptr;
+			const video_mode   *mode       = nullptr;
+			unsigned            row        = 0;
+			unsigned            col        = 0;
+			unsigned            hsync_lo   = 0;
+			unsigned            hsync_hi   = 0;
+			unsigned            vsync_hi   = 0;
+			unsigned            vsync_lo   = 0;
+			bool                last_hsync = false;
+			bool                last_vsync = false;
+			bool                found_line = false;
+			const std::uint32_t clock_hz;
+
+			std::array<bool, 4> keys = {};
+
+			void move_pos()      noexcept;
+			void scan_syncs()    noexcept;
+			void scan_vsync()    noexcept;
+			void put_pixel()     noexcept;
+			void guess_mode()    noexcept;
+			void signal_lost()   noexcept;
+			void update_window() noexcept;
+	};
+}
+
+#include "vga.impl.hpp"
+
+#endif
-- 
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