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       ieee1284_read_status, ieee1284_wait_status - analyse status lines


       #include <ieee1284.h>

       int ieee1284_read_status(struct parport *port);

       int ieee1284_wait_status(struct parport *port, unsigned char mask,
                                unsigned char val, struct timeval *timeout);


       There are five status lines, one of which is usually inverted on
       PC-style ports. Where they differ, libieee1284 operates on the IEEE
       1284 values, not the PC-style inverted values. The status lines are
       represented by the following enumeration:

           enum ieee1284_status_bits
             S1284_NFAULT = 0x08,
             S1284_SELECT = 0x10,
             S1284_PERROR = 0x20,
             S1284_NACK   = 0x40,
             S1284_BUSY   = 0x80,
             /* To convert those values into PC-style register values, use this: */
             S1284_INVERTED = S1284_BUSY,

       These functions all act on the parallel port associated with port,
       which must be claimed.

       The purpose of ieee1284_wait_status is to wait until particular status
       lines have specified values. Its timeout parameter may be modified on


       For ieee1284_read_status, the return value is a non-negative integer
       with bits set as appropriate representing the status lines. A negative
       result indicates an error.

       For ieee1284_wait_status, the return value is E1284_OK if the status
       lines now reflect the desired values (i.e. status & mask is val), or a
       negative result indicating an error.

       Possible error codes:

           The port lacks the required capability. This could be due to a
           limitation of this version of libieee1284, or a hardware

           Access to the status lines is not available on this port type.

           The timeout has elapsed.

           The port parameter is invalid (for instance, perhaps the port is
           not claimed).


       The nAck pin is often able to trigger interrupts on the host machine.
       With operating system help these interrupts may be visible to the
       application via the file descriptor returned by ieee1284_get_irq_fd.

       Under Linux, the conditions are that the parallel port driver knows
       which interrupt line to use and is using it, and that the relevant
       /dev/parport device node is accessible and backed by a device driver.


       Tim Waugh <>


       Copyright © 2001-2003 Tim Waugh

                                  09/18/2007                IEEE1284_STATUS(3)