Finish ppu, and mbc1 mapping

include/gamepad.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <common.h>
+
+typedef struct {
+    bool start;
+    bool select;
+    bool a;
+    bool b;
+    bool up;
+    bool down;
+    bool left;
+    bool right;
+} gamepad_state;
+
+void gamepad_init();
+bool gamepad_button_sel();
+bool gamepad_dir_sel();
+void gamepad_set_sel(u8 value);
+
+gamepad_state *gamepad_get_state();
+u8 gamepad_get_output();