| .. SPDX-License-Identifier: 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. |
