SYNOPSIS

       #include <ieee1284.h>


       int ieee1284_read_data (struct parport *port);

       void ieee1284_write_data (struct parport *port, unsigned char dt);

       int ieee1284_data_dir (struct parport *port, int reverse);

       int ieee1284_wait_data (struct parport *port, unsigned char mask,
                               unsigned char val, struct timeval *timeout);

DESCRIPTION

       These  functions manipulate the data lines of the parallel port associ-
       ated with port (which must have been claimed using  ieee1284_claim(3)).
       The  lines  are represented by an 8-bit number (one line per bit) and a
       direction. The data lines are driven  as  a  group;  they  may  be  all
       host-driven  (forward  direction)  or not (reverse direction). When the
       peripheral is driving them the host must not.


       For ieee1284_data_dir the reverse parameter should be zero to turn  the
       data line drivers on and non-zero to turn them off. Some port types may
       be unable to switch off the data line drivers.


       Setting the data lines may have side effects on some  port  types  (for
       example, some Amiga ports pulse nStrobe).


       ieee1284_wait_data waits, up until the timeout, for the data bits spec-
       ified in mask to have the corresponding values in val.

RETURN VALUE

       ieee1284_read_data returns the 8-bit number representing the data lines
       unless  it  is not possible to return such a value with this port type,
       in which case it returns an error code. Possible error codes:


       E1284_NOTAVAIL
              Bi-directional data lines are not available on this system.


       E1284_INVALIDPORT
              The port parameter is invalid (perhaps it has not been  claimed,
              for instance).

AUTHOR

       Tim Waugh <twaugh@redhat.com>.



                                                              IEEE1284_DATA(3)