[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>


.. c:function:: ssize_t read( int fd, void *buf, size_t count )
    :name: lirc-read


Arguments
=========

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

``buf``
   Buffer to be filled

``count``
   Max number of bytes to read

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
1b81f010	23	.. c:function:: ssize_t read( int fd, void *buf, size_t count )
e9de2d89	24	:name: lirc-read
8a6ba5c0 MCC	25
	26
	27	Arguments
	28	=========
	29
	30	``fd``
	31	File descriptor returned by ``open()``.
	32
	33	``buf``
15c19014	34	Buffer to be filled
8a6ba5c0	35
15c19014 MCC	36	``count``
15c19014 MCC	37	Max number of bytes to read
8a6ba5c0 MCC	38
	39	Description
	40	===========
	41
	42	:ref:`read() <lirc-read>` attempts to read up to ``count`` bytes from file
	43	descriptor ``fd`` into the buffer starting at ``buf``. If ``count`` is zero,
	44	:ref:`read() <lirc-read>` returns zero and has no other results. If ``count``
	45	is greater than ``SSIZE_MAX``, the result is unspecified.
5377d91f MH	46
	47	The lircd userspace daemon reads raw IR data from the LIRC chardev. The
	48	exact format of the data depends on what modes a driver supports, and
	49	what mode has been selected. lircd obtains supported modes and sets the
bd6a63f2 MCC	50	active mode via the ioctl interface, detailed at :ref:`lirc_func`.
	51	The generally preferred mode for receive is
	52	:ref:`LIRC_MODE_MODE2 <lirc-mode-mode2>`, in which packets containing an
	53	int value describing an IR signal are read from the chardev.
5377d91f MH	54
	55	See also
	56	`http://www.lirc.org/html/technical.html <http://www.lirc.org/html/technical.html>`__
	57	for more info.
8a6ba5c0 MCC	58
	59	Return Value
	60	============
	61
	62	On success, the number of bytes read is returned. It is not an error if
	63	this number is smaller than the number of bytes requested, or the amount
	64	of data required for one frame. On error, -1 is returned, and the ``errno``
	65	variable is set appropriately.