+// SDL function definitions
+
+void SDLSetAlpha(SDL_Surface *, boolean, int);
+const char *SDLGetRendererName(void);
+boolean SDLSetNativeSurface(SDL_Surface **);
+SDL_Surface *SDLGetNativeSurface(SDL_Surface *);
+SDL_Surface *SDLCreateNativeSurface(int, int, int);
+Bitmap *SDLGetBitmapFromSurface_WithMaskedColor(SDL_Surface *, int, int, int);
+Bitmap *SDLGetBitmapFromSurface(SDL_Surface *);
+void SDLCreateBitmapTextures(Bitmap *);
+void SDLFreeBitmapTextures(Bitmap *);
+