Blame doc/ieee1284_read_data.3

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.\"     Title: ieee1284_data
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.\"    Author: Tim Waugh <twaugh@redhat.com>
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.\" Generator: DocBook XSL Stylesheets v1.72.0 <http://docbook.sf.net/>
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.\"      Date: 09/18/2007
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.\"    Manual: Functions
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.\"    Source: 
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.\"
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.TH "IEEE1284_DATA" "3" "09/18/2007" "" "Functions"
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.SH "NAME"
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ieee1284_read_data, ieee1284_write_data, ieee1284_data_dir, ieee1284_wait_data \- control the data lines
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.SH "SYNOPSIS"
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.sp
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.ft B
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.nf
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#include <ieee1284.h>
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.fi
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.ft
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.HP 23
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.BI "int ieee1284_read_data(struct\ parport\ *" "port" ");"
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.HP 25
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.BI "void ieee1284_write_data(struct\ parport\ *" "port" ", unsigned\ char\ " "dt" ");"
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.HP 22
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.BI "int ieee1284_data_dir(struct\ parport\ *" "port" ", int\ " "reverse" ");"
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.HP 23
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.BI "int ieee1284_wait_data(struct\ parport\ *" "port" ", unsigned\ char\ " "mask" ", unsigned\ char\ " "val" ", struct\ timeval\ *" "timeout" ");"
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.SH "DESCRIPTION"
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.PP
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These functions manipulate the data lines of the parallel port associated with
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\fIport\fR
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(which must have been claimed using
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\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
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direction) or not (reverse
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direction). When the peripheral is driving them the host must not.
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.PP
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For
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\fBieee1284_data_dir\fR
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the
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\fIreverse\fR
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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.
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.PP
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Setting the data lines may have side effects on some port types (for example, some Amiga ports pulse nStrobe).
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.PP
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\fBieee1284_wait_data\fR
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waits, up until the
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\fItimeout\fR, for the data bits specified in
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\fImask\fR
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to have the corresponding values in
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\fIval\fR.
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.SH "RETURN VALUE"
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.PP
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\fBieee1284_read_data\fR
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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:
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.PP
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\fBE1284_NOTAVAIL\fR
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.RS 4
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Bi\-directional data lines are not available on this system.
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.RE
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.PP
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\fBE1284_INVALIDPORT\fR
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.RS 4
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The
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\fIport\fR
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parameter is invalid (perhaps it has not been claimed, for instance).
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.RE
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.PP
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\fBE1284_SYS\fR
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.RS 4
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There was an error at the operating system level, and
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\fIerrno\fR
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has been set accordingly.
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.RE
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.PP
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\fBE1284_TIMEDOUT\fR
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.RS 4
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The
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\fItimeout\fR
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has elapsed.
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.RE
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.PP
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Whereas
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\fBieee1284_read_data\fR
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may return
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\fBE1284_NOTAVAIL\fR
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on its first invocation on the port, if it does not do so then it cannot until
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\fBieee1284_close\fR
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is called for that port.
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.SH "AUTHOR"
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.PP
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\fBTim Waugh\fR <\&twaugh@redhat.com\&>
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.sp -1n
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.IP "" 4
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Author.
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.SH "COPYRIGHT"
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Copyright \(co 2001\-2003 Tim Waugh
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.br
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