Introduce Overlay Header and LBAs

include/PSX/Overlay/overlay.hpp

@@ -0,0 +1,13 @@
+#ifndef __JABYENGINE_OVERLAY__H__
+#define __JABYENGINE_OVERLAY__H__
+#include "../../stdint.h"
+
+typedef struct __attribute__((packed)) {
+    void (*execute)();
+} OverlayHeader;
+
+typedef struct __attribute__((packed)) {
+    uint16_t lba;
+    uint16_t size;
+} OverlayLBA;
+#endif //!__JABYENGINE_OVERLAY__H__

include/PSX/Overlay/overlay_declaration.hpp

@@ -0,0 +1,16 @@
+#ifndef __JABYENGINE_OVERLAY_DECLARATION__H__
+#define __JABYENGINE_OVERLAY_DECLARATION__H__
+
+// No include here because this header should be included in a namespace and we don't want multiple namespace definitions of OverlayHeader and OverlayLBA
+
+extern const OverlayHeader overlay_header;
+extern const OverlayLBA    overlay_lba[];
+
+#define __declare_overlay_header(function) \
+[[gnu::used]] \
+const OverlayHeader __section(".header") overlay_header = {.execute = &function};
+
+#define __declare_overlay_lbas(...) \
+[[gnu::used]] \
+const OverlayLBA __section(".header.lbas") overlay_lba[] = {__VA_ARGS__};
+#endif //!__JABYENGINE_OVERLAY_DECLARATION__H__