'\" t
.\"     Title: ieee1284_data
.\"    Author: Tim Waugh <twaugh@redhat.com>
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 04/07/2024
.\"    Manual: Functions
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "IEEE1284_DATA" "3" "04/07/2024" "[FIXME: source]" "Functions"
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.SH "NAME"
ieee1284_read_data, ieee1284_write_data, ieee1284_data_dir, ieee1284_wait_data \- control the data lines
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <ieee1284\&.h>
.fi
.ft
.HP \w'int\ ieee1284_read_data('u
.BI "int ieee1284_read_data(struct\ parport\ *" "port" ");"
.HP \w'void\ ieee1284_write_data('u
.BI "void ieee1284_write_data(struct\ parport\ *" "port" ", unsigned\ char\ " "dt" ");"
.HP \w'int\ ieee1284_data_dir('u
.BI "int ieee1284_data_dir(struct\ parport\ *" "port" ", int\ " "reverse" ");"
.HP \w'int\ ieee1284_wait_data('u
.BI "int ieee1284_wait_data(struct\ parport\ *" "port" ", unsigned\ char\ " "mask" ", unsigned\ char\ " "val" ", struct\ timeval\ *" "timeout" ");"
.SH "DESCRIPTION"
.PP
These functions manipulate the data lines of the parallel port associated with
\fIport\fR
(which must have been claimed using
\fBieee1284_claim\fR(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\&.
.PP
For
\fBieee1284_data_dir\fR
the
\fIreverse\fR
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\&.
.PP
Setting the data lines may have side effects on some port types (for example, some Amiga ports pulse nStrobe)\&.
.PP
\fBieee1284_wait_data\fR
waits, up until the
\fItimeout\fR, for the data bits specified in
\fImask\fR
to have the corresponding values in
\fIval\fR\&.
.SH "RETURN VALUE"
.PP
\fBieee1284_read_data\fR
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:
.PP
\fBE1284_NOTAVAIL\fR
.RS 4
Bi\-directional data lines are not available on this system\&.
.RE
.PP
\fBE1284_INVALIDPORT\fR
.RS 4
The
\fIport\fR
parameter is invalid (perhaps it has not been claimed, for instance)\&.
.RE
.PP
\fBE1284_SYS\fR
.RS 4
There was an error at the operating system level, and
\fIerrno\fR
has been set accordingly\&.
.RE
.PP
\fBE1284_TIMEDOUT\fR
.RS 4
The
\fItimeout\fR
has elapsed\&.
.RE
.PP
Whereas
\fBieee1284_read_data\fR
may return
\fBE1284_NOTAVAIL\fR
on its first invocation on the port, if it does not do so then it cannot until
\fBieee1284_close\fR
is called for that port\&.
.SH "AUTHOR"
.PP
\fBTim Waugh\fR <\&twaugh@redhat.com\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br
Copyright \(co 2001-2003 Tim Waugh
.br