+// SDL function definitions
+
+void SDLSetAlpha(SDL_Surface *, boolean, int);
+const char *SDLGetRendererName(void);
+boolean SDLSetNativeSurface(SDL_Surface **);
+SDL_Surface *SDLGetNativeSurface(SDL_Surface *);
+void SDLCreateBitmapTextures(Bitmap *);
+void SDLFreeBitmapTextures(Bitmap *);
+
+SDL_Surface *SDL_DisplayFormat(SDL_Surface *);
+void SDLSetWindowScaling(int);
+void SDLSetWindowScalingQuality(char *);
+void SDLSetWindowFullscreen(boolean);
+void SDLSetDisplaySize(void);
+void SDLSetScreenSizeAndOffsets(int, int);
+void SDLSetScreenSizeForRenderer(int, int);
+void SDLSetScreenProperties(void);
+
+void SDLSetScreenRenderingMode(char *);
+void SDLSetScreenVsyncMode(char *);
+void SDLRedrawWindow(void);
+void SDLSetWindowTitle(void);
+
+void SDLLimitScreenUpdates(boolean);