| .. -*- 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. |
