IEEE1284_REF(3) Functions IEEE1284_REF(3)NAME
ieee1284_ref, ieee1284_unref - modify a port's reference count
int ieee1284_ref(struct parport *port);
int ieee1284_unref(struct parport *port);
If you want to free the port list from ieee1284_find_ports but open one of the ports later on, you will need to prevent it from being
destroyed in ieee1284_free_ports. Each port has a reference count, and you can use ieee1284_ref to increment it and ieee1284_unref to
If you use ieee1284_ref at any stage, you must later call ieee1284_unref to relinquish the extra reference. If you do not do this, the
resources associated with the port will not be cleaned up.
If you have not previously used ieee1284_ref on a port, you must not use ieee1284_unref on it.
These functions return the number of references held after the increment or decrement.
SEE ALSO ieee1284_open(3)AUTHOR
Tim Waugh <firstname.lastname@example.org>
Copyright (C) 2001-2003 Tim Waugh
[FIXME: source] 06/17/2014 IEEE1284_REF(3)
Check Out this Related Man Page
IEEE1284_DATA(3) Functions IEEE1284_DATA(3)NAME
ieee1284_read_data, ieee1284_write_data, ieee1284_data_dir, ieee1284_wait_data - control the data lines
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);
These functions manipulate the data lines of the parallel port associated 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 specified in mask to have the corresponding values in val.
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:
Bi-directional data lines are not available on this system.
The port parameter is invalid (perhaps it has not been claimed, for instance).
There was an error at the operating system level, and errno has been set accordingly.
The timeout has elapsed.
Whereas ieee1284_read_data may return E1284_NOTAVAIL on its first invocation on the port, if it does not do so then it cannot until
ieee1284_close is called for that port.
Tim Waugh <email@example.com>
Copyright (C) 2001-2003 Tim Waugh
[FIXME: source] 06/17/2014 IEEE1284_DATA(3)
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