82 lines
2.5 KiB
ReStructuredText
82 lines
2.5 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
|
|
.. document under the terms of the GNU Free Documentation License,
|
|
.. Version 1.1 or any later version published by the Free Software
|
|
.. Foundation, with no Invariant Sections, no Front-Cover Texts
|
|
.. and no Back-Cover Texts. A copy of the license is included at
|
|
.. Documentation/media/uapi/fdl-appendix.rst.
|
|
..
|
|
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
|
|
|
|
.. _lirc-write:
|
|
|
|
************
|
|
LIRC write()
|
|
************
|
|
|
|
Name
|
|
====
|
|
|
|
lirc-write - Write to a LIRC device
|
|
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. code-block:: c
|
|
|
|
#include <unistd.h>
|
|
|
|
|
|
.. c:function:: ssize_t write( int fd, void *buf, size_t count )
|
|
:name: lirc-write
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by ``open()``.
|
|
|
|
``buf``
|
|
Buffer with data to be written
|
|
|
|
``count``
|
|
Number of bytes at the buffer
|
|
|
|
Description
|
|
===========
|
|
|
|
:ref:`write() <lirc-write>` writes up to ``count`` bytes to the device
|
|
referenced by the file descriptor ``fd`` from the buffer starting at
|
|
``buf``.
|
|
|
|
The exact format of the data depends on what mode a driver is in, use
|
|
:ref:`lirc_get_features` to get the supported modes and use
|
|
:ref:`lirc_set_send_mode` set the mode.
|
|
|
|
When in :ref:`LIRC_MODE_PULSE <lirc-mode-PULSE>` mode, the data written to
|
|
the chardev is a pulse/space sequence of integer values. Pulses and spaces
|
|
are only marked implicitly by their position. The data must start and end
|
|
with a pulse, therefore, the data must always include an uneven number of
|
|
samples. The write function blocks until the data has been transmitted
|
|
by the hardware. If more data is provided than the hardware can send, the
|
|
driver returns ``EINVAL``.
|
|
|
|
When in :ref:`LIRC_MODE_SCANCODE <lirc-mode-scancode>` mode, one
|
|
``struct lirc_scancode`` must be written to the chardev at a time, else
|
|
``EINVAL`` is returned. Set the desired scancode in the ``scancode`` member,
|
|
and the protocol in the :c:type:`rc_proto`: member. All other members must be
|
|
set to 0, else ``EINVAL`` is returned. If there is no protocol encoder
|
|
for the protocol or the scancode is not valid for the specified protocol,
|
|
``EINVAL`` is returned. The write function blocks until the scancode
|
|
is transmitted by the hardware.
|
|
|
|
|
|
Return Value
|
|
============
|
|
|
|
On success, the number of bytes written 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. The generic error codes are described at the
|
|
:ref:`Generic Error Codes <gen-errors>` chapter.
|