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       ieee1284_get_deviceid - retrieve an IEEE 1284 Device ID


       #include <ieee1284.h>

       ssize_t ieee1284_get_deviceid(struct parport *port, int daisy,
                                     int flags, char *buffer, size_t len);


       This function is for retrieving the IEEE 1284 Device ID of the
       specified device. The device is specified by the port to which it is
       attached, and optionally an address (daisy) on the daisy chain of
       devices on that port.

       daisy should be â1 to indicate that the device is not participating in
       a IEEE 1284.3 daisy chain, meaning it is the last (or only) device on
       the port, or should be a number from 0 to 3 inclusive to indicate that
       it has the specified daisy chain address (0 is next to the port).

       The flags parameter should be a bitwise union of any flags that the
       program wants to use. Available flags are:

           Guarantee a fresh Device ID. A cached or OS-provided ID will not be

       The provided buffer must be at least len bytes long, and will contain
       the Device ID including the initial two-byte length field and a
       terminating zero byte on successful return, or as much of the above as
       will fit into the buffer.


       A return value less than zero indicates an error as below. Otherwise,
       the return value is the number of bytes of buffer that have been
       filled. A return value equal to the length of the buffer indicates that
       the Device ID may be longer than the buffer will allow.

           The device did not provide an IEEE 1284 Device ID when interrogated
           (perhaps by the operating system if F1284_FRESH was not specified).

           One or more of the supplied flags is not supported in this
           implementation, or if no flags were supplied then this function is
           not implemented for this type of port or this type of system. This
           can also be returned if a daisy chain address is specified but
           daisy chain Device IDs are not yet supported.

           F1284_FRESH was specified and the library is unable to access the
           port to interrogate the device.

           There is not enough memory.

           There was a problem initializing the port.

           The port parameter is invalid.


       Unless the F1284_FRESH flag is given, the library will try to find the
       device’s ID as unobtrusively as possible. First it will ask the
       operating system if it knows it, and then it will try actually asking
       the device for it. Because of this, the Device ID may be partially
       computed (the length field, for example) or even partially missing if
       the operating system has only remembered some parts of the ID. To
       guarantee that you are getting the bytes that the device sent, use
       F1284_FRESH. Be aware that the operating system may allow any user to
       inspect the Device IDs that it provides, whereas device access is
       normally more restricted.

       The initial two-byte length field is a big-endian 16 bit unsigned
       integer provided by the device and may not be accurate. In particular,
       it is meant to indicate the length of the entire string including the
       length field itself; however, some manufacturers exclude the length
       field or just set the length field to some arbitrary number greater
       than the ID length.


       Tim Waugh <>


       Copyright © 2001-2003 Tim Waugh

                                  09/18/2007           IEEE1284_GET_DEVICEI(3)