Read pending control events
#include <sys/asoundlib.h> int snd_ctl_read( snd_ctl_t *handle, snd_ctl_callbacks_t *callbacks );
- The handle for the control connection to the card. This must be a handle created by snd_ctl_open() .
- A pointer to a snd_ctl_callbacks_t structure that defines the callbacks for the events.
Use the -l asound option to qcc to link against this library.
The snd_ctl_read() function reads pending control events from the control handle. As each event is read, the list of callbacks is checked for a handler for this event. If a match is found, the callback is invoked. This function is usually called on the return of the select() library call (see the QNX Library Reference).
The number of events read from the handle, or a negative value on error.
- Invalid file descriptor. Your handle may be corrupt.
- The read operation was interrupted by a signal, and either no data was transferred, or the resource manager responsible for that file doesn't report partial transfers.
- An event I/O error occurred.