Paste: better?

<PRIVATE
: mask-index   ( event -- n ) -3 shift ;
: bitmask ( event -- n ) 7 bitand 2^ ;
PRIVATE>

:: 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 ;