'\" t
.\"     Title: ieee1284_status
.\"    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_STATUS" "3" "04/07/2024" "[FIXME: source]" "Functions"
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.SH "NAME"
ieee1284_read_status, ieee1284_wait_status \- analyse status lines
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <ieee1284\&.h>
.fi
.ft
.HP \w'int\ ieee1284_read_status('u
.BI "int ieee1284_read_status(struct\ parport\ *" "port" ");"
.HP \w'int\ ieee1284_wait_status('u
.BI "int ieee1284_wait_status(struct\ parport\ *" "port" ", unsigned\ char\ " "mask" ", unsigned\ char\ " "val" ", struct\ timeval\ *" "timeout" ");"
.SH "DESCRIPTION"
.PP
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:
.sp
.if n \{\
.RS 4
.\}
.nf
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,
};
.fi
.if n \{\
.RE
.\}
.PP
These functions all act on the parallel port associated with
\fIport\fR, which must be claimed\&.
.PP
The purpose of
\fBieee1284_wait_status\fR
is to wait until particular status lines have specified values\&. Its
\fItimeout\fR
parameter may be modified on return\&.
.SH "RETURN VALUE"
.PP
For
\fBieee1284_read_status\fR, the return value is a non\-negative integer with bits set as appropriate representing the status lines\&. A negative result indicates an error\&.
.PP
For
\fBieee1284_wait_status\fR, the return value is
\fBE1284_OK\fR
if the status lines now reflect the desired values (i\&.e\&. status &
\fImask\fR
is
\fIval\fR), or a negative result indicating an error\&.
.PP
Possible error codes:
.PP
\fBE1284_NOTIMPL\fR
.RS 4
The
\fIport\fR
lacks the required capability\&. This could be due to a limitation of this version of libieee1284, or a hardware limitation\&.
.RE
.PP
\fBE1284_NOTAVAIL\fR
.RS 4
Access to the status lines is not available on this port type\&.
.RE
.PP
\fBE1284_TIMEDOUT\fR
.RS 4
The
\fItimeout\fR
has elapsed\&.
.RE
.PP
\fBE1284_INVALIDPORT\fR
.RS 4
The
\fIport\fR
parameter is invalid (for instance, perhaps the
\fIport\fR
is not claimed)\&.
.RE
.SH "NOTES"
.PP
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
\fBieee1284_get_irq_fd\fR\&.
.PP
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\&.
.SH "AUTHOR"
.PP
\fBTim Waugh\fR <\&twaugh@redhat.com\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br
Copyright \(co 2001-2003 Tim Waugh
.br