extern void x_reference_bitmap (struct frame *, ptrdiff_t);
extern ptrdiff_t x_create_bitmap_from_data (struct frame *, char *,
unsigned int, unsigned int);
extern void x_reference_bitmap (struct frame *, ptrdiff_t);
extern ptrdiff_t x_create_bitmap_from_data (struct frame *, char *,
unsigned int, unsigned int);