.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later .. c:namespace:: RC

.. _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 )

Arguments

fd File descriptor returned by open().

buf Buffer to be filled

count Max number of bytes to read

Description

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

The exact format of the data depends on what :ref:lirc_modes a driver uses. Use :ref:lirc_get_features to get the supported mode, and use :ref:lirc_set_rec_mode set the current active mode.

The mode :ref:LIRC_MODE_MODE2 <lirc-mode-mode2> is for raw IR, in which packets containing an unsigned int value describing an IR signal are read from the chardev.

Alternatively, :ref:LIRC_MODE_SCANCODE <lirc-mode-scancode> can be available, in this mode scancodes which are either decoded by software decoders, or by hardware decoders. The :c:type:rc_proto member is set to the :ref:IR protocol <Remote_controllers_Protocols> used for transmission, and scancode to the decoded scancode, and the keycode set to the keycode or KEY_RESERVED.

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.