ieee1284_epp_read_addr,                        ieee1284_epp_write_addr,
       ieee1284_ecp_read_data,                        ieee1284_ecp_write_data,
       ieee1284_ecp_read_addr,  ieee1284_ecp_write_addr  - data transfer func-
       tions

SYNOPSIS

       #include <ieee1284.h>


       ssize_t ieee1284_nibble_read (struct parport *port, int flags,
                                     char *buffer, size_t len);

       ssize_t ieee1284_compat_write (struct parport *port, int flags,
                                      const char *buffer, size_t len);

       ssize_t ieee1284_byte_read (struct parport *port, int flags,
                                   char *buffer, size_t len);

       ssize_t ieee1284_epp_read_data (struct parport *port, int flags,
                                       char *buffer, size_t len);

       ssize_t ieee1284_epp_write_data (struct parport *port, int flags,
                                        const char *buffer, size_t len);

       ssize_t ieee1284_epp_read_addr (struct parport *port, int flags,
                                       char *buffer, size_t len);

       ssize_t ieee1284_epp_write_addr (struct parport *port, int flags,
                                        const char *buffer, size_t len);

       ssize_t ieee1284_ecp_read_data (struct parport *port, int flags,
                                       char *buffer, size_t len);

       ssize_t ieee1284_ecp_write_data (struct parport *port, int flags,
                                        const char *buffer, size_t len);

       ssize_t ieee1284_ecp_read_addr (struct parport *port, int flags,
                                       char *buffer, size_t len);

       ssize_t ieee1284_ecp_write_addr (struct parport *port, int flags,
                                        const char *buffer, size_t len);

DESCRIPTION

       This set of functions is for tranferring bytes in the relevant transfer
       mode. For ECP and EPP modes two types of transfer  are  possible:  data
       and address (usually referred to as channel in ECP).


       The supplied port must be a claimed port.


       data  before  the inactivity time-out elapses it is sent; otherwise the
       return value will be E1284_TIMEDOUT


       The flags may alter the behaviour slightly:


       F1284_NONBLOCK
              For reads (peripheral to host): if no data is available,  return
              immediately (with E1284_TIMEDOUT).

              For  writes (host to peripheral): if the peripheral is not will-
              ing to accept data, return immediately (with E1284_TIMEDOUT).


       F1284_SWE
              Don't use hardware assistance for the transfer, but instead  set
              the parallel port pins according to the wire protocol.


       F1284_RLE (for ECP only)
              Use  run  length encoding. If the peripheral is in ECP mode with
              RLE, calls to ieee1284_ecp_read_data  must set this flag in  or-
              der for the RLE from the peripheral to be interpreted correctly,
              and calls to ieee1284_ecp_write_data  may set this flag in order
              to take advantage of RLE.


       F1284_FASTEPP (for EPP only)
              Use  multi-byte  transfers.  Several  bytes at a time are trans-
              ferred using hardware  assistance,  if  supporting  hardware  is
              present.  The  price  of this increased speed is that the return
              value will be less reliable when this flag is used.


       For ECP mode, a given direction is in force at any particular time, and
       it  is  up to the application to ensure that it is only writing when in
       forward mode, and reading when in reverse mode.

RETURN VALUE

       The return value is the number of bytes successfully transferred or, if
       negative, one of:


       E1284_NOTIMPL
              This  transfer mode and flags combination is not yet implemented
              in libieee1284.


       E1284_TIMEDOUT
              Timed out waiting for peripheral to handshake.


       If any bytes are successfully transferred, that number is returned.  An
       error is returned only if no bytes are transferred.


       For  host-to-peripheral transfers, all data is at the peripheral by the
       time the call returns.

SEE ALSO

       ieee1284_ecp_fwd_to_rev(3)

AUTHOR

       Tim Waugh <twaugh@redhat.com>.



                                                          IEEE1284_TRANSFER(3)