6.5.1. LIRC read()¶

6.5.1.1. Name¶

lirc-read - Read from a LIRC device

6.5.1.2. Synopsis¶

#include <unistd.h>

ssize_t read(int fd, void *buf, size_t count)¶

6.5.1.3. Arguments¶

fd: File descriptor returned by open().
buf: Buffer to be filled
count: Max number of bytes to read

6.5.1.4. Description¶

read() attempts to read up to count bytes from file descriptor fd into the buffer starting at buf. If count is zero, 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 LIRC modes a driver uses. Use ioctl LIRC_GET_FEATURES to get the supported mode, and use ioctls LIRC_GET_REC_MODE and LIRC_SET_REC_MODE set the current active mode.

The mode 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, LIRC_MODE_SCANCODE can be available, in this mode scancodes which are either decoded by software decoders, or by hardware decoders. The rc_proto member is set to the IR protocol used for transmission, and scancode to the decoded scancode, and the keycode set to the keycode or KEY_RESERVED.

6.5.1.5. 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.