Prepare CD code and unify header names

src/Library/include/CD/cd.hpp

@@ -0,0 +1,18 @@
+#ifndef __JABYENGINE_CD_HPP__
+#define __JABYENGINE_CD_HPP__
+#include <stdint.h>
+
+namespace CD {
+    namespace CircularBuffer {
+        extern uint8_t* write_ptr;
+        extern uint8_t* read_ptr;
+        extern uint8_t* end_ptr;
+    }
+
+    enum struct State {
+    };
+
+    extern State state;
+}
+
+#endif //!__JABYENGINE_CD_HPP__

src/Library/include/GPU/gpu.hpp

@@ -1,8 +1,8 @@
 #ifndef __JABYENGINE_INTERNAL_GPU_HPP__
 #define __JABYENGINE_INTERNAL_GPU_HPP__
-#include <PSX/GPU/GPU.hpp>
-#include <PSX/System/IOPorts/DMA_IO.hpp>
-#include <PSX/System/IOPorts/GPU_IO.hpp>
+#include <PSX/GPU/gpu.hpp>
+#include <PSX/System/IOPorts/dma_io.hpp>
+#include <PSX/System/IOPorts/gpu_io.hpp>
 
 namespace GPU {
     namespace Screen {