1*4882a593Smuzhiyun.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2*4882a593Smuzhiyun.. c:namespace:: RC 3*4882a593Smuzhiyun 4*4882a593Smuzhiyun.. _lirc-read: 5*4882a593Smuzhiyun 6*4882a593Smuzhiyun*********** 7*4882a593SmuzhiyunLIRC read() 8*4882a593Smuzhiyun*********** 9*4882a593Smuzhiyun 10*4882a593SmuzhiyunName 11*4882a593Smuzhiyun==== 12*4882a593Smuzhiyun 13*4882a593Smuzhiyunlirc-read - Read from a LIRC device 14*4882a593Smuzhiyun 15*4882a593SmuzhiyunSynopsis 16*4882a593Smuzhiyun======== 17*4882a593Smuzhiyun 18*4882a593Smuzhiyun.. code-block:: c 19*4882a593Smuzhiyun 20*4882a593Smuzhiyun #include <unistd.h> 21*4882a593Smuzhiyun 22*4882a593Smuzhiyun.. c:function:: ssize_t read( int fd, void *buf, size_t count ) 23*4882a593Smuzhiyun 24*4882a593SmuzhiyunArguments 25*4882a593Smuzhiyun========= 26*4882a593Smuzhiyun 27*4882a593Smuzhiyun``fd`` 28*4882a593Smuzhiyun File descriptor returned by ``open()``. 29*4882a593Smuzhiyun 30*4882a593Smuzhiyun``buf`` 31*4882a593Smuzhiyun Buffer to be filled 32*4882a593Smuzhiyun 33*4882a593Smuzhiyun``count`` 34*4882a593Smuzhiyun Max number of bytes to read 35*4882a593Smuzhiyun 36*4882a593SmuzhiyunDescription 37*4882a593Smuzhiyun=========== 38*4882a593Smuzhiyun 39*4882a593Smuzhiyun:c:func:`read()` attempts to read up to ``count`` bytes from file 40*4882a593Smuzhiyundescriptor ``fd`` into the buffer starting at ``buf``. If ``count`` is zero, 41*4882a593Smuzhiyun:c:func:`read()` returns zero and has no other results. If ``count`` 42*4882a593Smuzhiyunis greater than ``SSIZE_MAX``, the result is unspecified. 43*4882a593Smuzhiyun 44*4882a593SmuzhiyunThe exact format of the data depends on what :ref:`lirc_modes` a driver 45*4882a593Smuzhiyunuses. Use :ref:`lirc_get_features` to get the supported mode, and use 46*4882a593Smuzhiyun:ref:`lirc_set_rec_mode` set the current active mode. 47*4882a593Smuzhiyun 48*4882a593SmuzhiyunThe mode :ref:`LIRC_MODE_MODE2 <lirc-mode-mode2>` is for raw IR, 49*4882a593Smuzhiyunin which packets containing an unsigned int value describing an IR signal are 50*4882a593Smuzhiyunread from the chardev. 51*4882a593Smuzhiyun 52*4882a593SmuzhiyunAlternatively, :ref:`LIRC_MODE_SCANCODE <lirc-mode-scancode>` can be available, 53*4882a593Smuzhiyunin this mode scancodes which are either decoded by software decoders, or 54*4882a593Smuzhiyunby hardware decoders. The :c:type:`rc_proto` member is set to the 55*4882a593Smuzhiyun:ref:`IR protocol <Remote_controllers_Protocols>` 56*4882a593Smuzhiyunused for transmission, and ``scancode`` to the decoded scancode, 57*4882a593Smuzhiyunand the ``keycode`` set to the keycode or ``KEY_RESERVED``. 58*4882a593Smuzhiyun 59*4882a593SmuzhiyunReturn Value 60*4882a593Smuzhiyun============ 61*4882a593Smuzhiyun 62*4882a593SmuzhiyunOn success, the number of bytes read is returned. It is not an error if 63*4882a593Smuzhiyunthis number is smaller than the number of bytes requested, or the amount 64*4882a593Smuzhiyunof data required for one frame. On error, -1 is returned, and the ``errno`` 65*4882a593Smuzhiyunvariable is set appropriately. 66