TTY_HAVEXDA
(TTY_HAVEDA|TTY_HAVEDA2|TTY_HAVEXDA)
if (tty->flags & TTY_HAVEXDA)
tty->flags |= TTY_HAVEXDA;
if ((tty->flags & (TTY_HAVEDA|TTY_HAVEDA2|TTY_HAVEXDA)) == 0)
if (~tty->flags & TTY_HAVEXDA)