alCheckEvent(3dm)                                            alCheckEvent(3dm)


NAME
     alCheckEvent - Looks for an event in the event queue and retrieves it.

SYNOPSIS
     #include <dmedia/audio.h>

     int alCheckEvent(ALeventQueue eventq,int src,int param,ALevent event)

PARAMETER
     eventq   expects an ALeventQueue structure from which you want to
              retrieve audio events.

     src      expects an int with the value of the resource that generated or
              posted the audio event.

     param    expects an int with the value of the parameter for the audio
              event.

     event    expects an ALevent structure previously initialized by
              alNewEvent(3dm).


DESCRIPTION
     matches its fields with param and src and places it on event.  This call
     will not block if the event is not found, or the event queue is empty.
     Note that src refers to the resource that generated or posted the event,
     please refer to alSelectEvents(3dm) and alParams(3dm) for more
     information.

     To process the event, use the following calls: alGetEventParam(3dm),
     alGetEventUST(3dm), alGetEventValue(3dm), alGetEventData(3dm),
     alGetEventResource(3dm),  and alGetEventSrcResource(3dm).

EXAMPLE
     The following examples tries to retrieve an event from an event queue
     through alCheckEvent(3dm).  The event should have an AL_GAIN parameter
     and the its resource should be the AL_DEFAULT_INPUT.

     int     param;
     ALevent event;
     /*
      * Initialize an ALevent structure.
      */

     event = alNewEvent();
     if(event == NULL) {
       fprintf(stderr,"Event allocation failed: %s",
       alGetErrorString(oserror()));
       exit(-1);
     }


     /*
      * Check for the event
      */
     param = AL_GAIN;
     resource = AL_DEFAULT_INPUT;

     status = alCheckEvent(eventq,param,resource,event);
     if(status == -1) {
       fprintf(stderr,"Event was not found: %s",
       alGetErrorString(oserror()));
       exit(-1);
     }


DIAGNOSTICS
     Upon successful completion, alCheckEvent returns 0.

     Otherwise, alCheckEvent returns -1 and sets an error number which can be
     retrieved with oserror(3C).

     alCheckEvent can fail for the following reason:

     AL_BAD_INVALID_EVENTQ    eventq is either invalid or null.

     AL_BAD_INVALID_EVENT     event is either invalid or null.

     AL_BAD_EVENT_NOT_FOUND   An event match was not found in eventq.

SEE ALSO
     alOpenEventQueue(3dm), alSelectEvents(2), alGetEventParam(3dm),
     alGetEventUST(3dm), alGetEventValue(3dm), alGetEventData(3dm),
     alGetEventResource(3dm), alGetEventSrcResource(3dm), alParams(3dm),
     oserror(3C)


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