BMAP_INUSE
#define BMAP_IS_INUSE(b) ((b)->bm_flags & BMAP_INUSE)
BMAP_SET_FLAGS(bmp, BMAP_INUSE);
BMAP_UNSET_FLAGS(bmp, BMAP_INUSE);
BMAP_SET_FLAGS(bmp, BMAP_INUSE);
BMAP_UNSET_FLAGS(bmp, BMAP_INUSE);