[deliverable/linux.git] / Documentation / media / uapi / rc / lirc-read.rst

.. -*- coding: utf-8; mode: rst -*-

.. _lirc-read:

***********
LIRC read()
***********

Name
====

lirc-read - Read from a LIRC device


Synopsis
========

.. code-block:: c

    #include <unistd.h>


.. cpp:function:: ssize_t read( int fd, void *buf, size_t count )


Arguments
=========

``fd``
    File descriptor returned by ``open()``.

``buf``
``count``


Description
===========

:ref:`read() <lirc-read>` attempts to read up to ``count`` bytes from file
descriptor ``fd`` into the buffer starting at ``buf``.  If ``count`` is zero,
:ref:`read() <lirc-read>` returns zero and has no other results. If ``count``
is greater than ``SSIZE_MAX``, the result is unspecified.

The lircd userspace daemon reads raw IR data from the LIRC chardev. The
exact format of the data depends on what modes a driver supports, and
what mode has been selected. lircd obtains supported modes and sets the
active mode via the ioctl interface, detailed at :ref:`lirc_func`.
The generally preferred mode for receive is
:ref:`LIRC_MODE_MODE2 <lirc-mode-mode2>`, in which packets containing an
int value describing an IR signal are read from the chardev.

See also
`http://www.lirc.org/html/technical.html <http://www.lirc.org/html/technical.html>`__
for more info.

Return Value
============

On success, the number of bytes read is returned. It is not an error if
this number is smaller than the number of bytes requested, or the amount
of data required for one frame.  On error, -1 is returned, and the ``errno``
variable is set appropriately.
Commit	Line	Data
5377d91f MH	1	.. -- coding: utf-8; mode: rst --
5377d91f MH	2
4ed030af	3	.. _lirc-read:
5377d91f	4
8a6ba5c0 MCC	5	***********
	6	LIRC read()
	7	***********
	8
	9	Name
	10	====
	11
	12	lirc-read - Read from a LIRC device
	13
	14
	15	Synopsis
	16	========
	17
	18	.. code-block:: c
	19
	20	#include <unistd.h>
	21
	22
	23	.. cpp:function:: ssize_t read( int fd, void *buf, size_t count )
	24
	25
	26	Arguments
	27	=========
	28
	29	``fd``
	30	File descriptor returned by ``open()``.
	31
	32	``buf``
	33	``count``
	34
	35
	36	Description
	37	===========
	38
	39	:ref:`read() <lirc-read>` attempts to read up to ``count`` bytes from file
	40	descriptor ``fd`` into the buffer starting at ``buf``. If ``count`` is zero,
	41	:ref:`read() <lirc-read>` returns zero and has no other results. If ``count``
	42	is greater than ``SSIZE_MAX``, the result is unspecified.
5377d91f MH	43
	44	The lircd userspace daemon reads raw IR data from the LIRC chardev. The
	45	exact format of the data depends on what modes a driver supports, and
	46	what mode has been selected. lircd obtains supported modes and sets the
bd6a63f2 MCC	47	active mode via the ioctl interface, detailed at :ref:`lirc_func`.
	48	The generally preferred mode for receive is
	49	:ref:`LIRC_MODE_MODE2 <lirc-mode-mode2>`, in which packets containing an
	50	int value describing an IR signal are read from the chardev.
5377d91f MH	51
	52	See also
	53	`http://www.lirc.org/html/technical.html <http://www.lirc.org/html/technical.html>`__
	54	for more info.
8a6ba5c0 MCC	55
	56	Return Value
	57	============
	58
	59	On success, the number of bytes read is returned. It is not an error if
	60	this number is smaller than the number of bytes requested, or the amount
	61	of data required for one frame. On error, -1 is returned, and the ``errno``
	62	variable is set appropriately.