Read pending control events
#include <sys/asoundlib.h> int snd_ctl_read( snd_ctl_t *handle, snd_ctl_callbacks_t *callbacks );
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 Neutrino C Library Reference).
By default, events are disabled and an application must enable them using snd_ctl_set_filter(). Use snd_ctl_set_filter() and snd_ctl_get_filter() to tell io-audio which events you are interested in monitoring, handling, or both.
The number of events read from the handle, or a negative value on error.
QNX Neutrino
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | Yes |
Thread | Yes |