anchor.diff:   *  surface.
    *}
   
  -function SDL_ConvertSurface(SDL_Surface * src, SDL_PixelFormat * fmt, Uint32 flags): PSDLSurface;
  -function SDL_ConvertSurfaceFormat(SDL_Surface * src, Uint32 pixel_format, Uint32 flags): PSDLSurface;
  +function SDL_ConvertSurface(src: PSDLSurface; fmt: PSDLPixelFormat; flags: UInt32): PSDLSurface cdecl external {$IFDEF GPC} name 'SDL_ConvertSurface' {$ELSE} SDL_LibName {$ENDIF};
  +function SDL_ConvertSurfaceFormat(src: PSDLSurface; pixel_format: UInt32; flags: UInt32): PSDLSurface cdecl external {$IFDEF GPC} name 'SDL_ConvertSurfaceFormat' {$ELSE} SDL_LibName {$ENDIF};
   
   {**
    *  Copy a block of pixels of one format to another format
  
positive.code:  *  This function uses a static buffer, and is not thread-safe.
   *}
  
  function SDL_SoftStretch(src: PSDLSurface; const srcrect: PSDLRect; dst: PSDLSurface; const dstrect: PSDLSurface);
  
  SDL_BlitScaled = SDL_UpperBlitScaled;
  
  
negative.code:   Result := (A.x = B.x) and (A.y = B.y) and (A.w = B.w) and (A.h = B.h);
  end;
  
  //from "sdl_pixels.h"
  function SDL_IsPixelFormat_FOURCC(format: Variant): Boolean;
  begin
    {* The flag is set to 1 because 0x1? is not in the printable ASCII range *}
    Result := format and SDL_PIXELFLAG(format) <> 1;
  end;
  
  //from "sdl_surface.h"
  function SDL_LoadBMP(file_: PChar);
  begin
  