:: XISetMask ( mask event -- ) event mask-index :> index event bitmask index mask nth bitor index mask set-nth ; inline :: XIClearMask ( mask event -- ) event mask-index :> index event bitmask bitnot index mask nth bitand index mask set-nth ; inline :: XIMaskIsSet ( mask event -- n ) event mask-index :> index event bitmask index mask nth bitand ; : XIMaskLen ( event -- n ) 7 + -3 shift ;