// This code example shows all USB Audio Function Driver possible events and
// a possible scheme for handling these events. In this case event responses
// are not deferred.

void APP_USBDeviceAudioEventHandler
(
    USB_DEVICE_AUDIO_INDEX instanceIndex ,
    USB_DEVICE_AUDIO_EVENT event ,
    void * pData,
    uintptr_t context
)
{
    switch (event)
    {
        case USB_DEVICE_AUDIO_EVENT_READ_COMPLETE:

            // This event indicates that a Audio Read Transfer request
            // has completed. pData should be interpreted as a 
            // USB_DEVICE_AUDIO_EVENT_DATA_READ_COMPLETE pointer type.
            // This contains the transfer handle of the read transfer
            // that completed and amount of data that was read.

            break;
        
        case USB_DEVICE_AUDIO_EVENT_WRITE_COMPLETE:

            // This event indicates that a Audio Write Transfer request
            // has completed. pData should be interpreted as a 
            // USB_DEVICE_AUDIO_EVENT_DATA_WRITE_COMPLETE pointer type.
            // This contains the transfer handle of the write transfer
            // that completed and amount of data that was written.

            break;

        case USB_DEVICE_AUDIO_EVENT_STATUS_SEND_COMPLETE:
            // This event indicates that a Audio Status Write Transfer
            // request on the interrupt Endpoint has been completed. pData 
            // should be interpreted as a 
            // USB_DEVICE_AUDIO_EVENT_DATA_STATUS_SEND_COMPLETE pointer type.
            // This contains the transfer handle of the transfer.

            break;


        case USB_DEVICE_AUDIO_EVENT_INTERFACE_SETTING_CHANGED:

            // This event occurs when the host sends Set Interface request
            // to the Audio USB Device. pData will be a pointer to a
            // USB_DEVICE_AUDIO_EVENT_DATA_INTERFACE_SETTING_CHANGED. This
            // contains the interface number whose setting was
            // changed and the index of the alternate setting.
            // The application should typically enable the audio function
            // if the interfaceAlternateSettting member of pData is greater
            // than 0.

            break;
        
        case USB_DEVICE_AUDIO_EVENT_CONTROL_TRANSFER_UNKNOWN:
         
            // This event indicates that the Audio function driver has
            // received a control transfer which it cannot decode. pData
            // will be a pointer to USB_SETUP_PACKET type pointer. The
            // application should decode the packet and take the required
            // action using the USB_DEVICE_ControlStatus(),
            // USB_DEVICE_ControlSend() and USB_DEVICE_ControlReceive()
            // functions.

            break;

        case USB_DEVICE_AUDIO_EVENT_CONTROL_TRANSFER_DATA_SENT:
            
            // This event indicates the data send request associated with
            // the latest USB_DEVICE_ControlSend() function was
            // completed. pData will be NULL. 

        case USB_DEVICE_AUDIO_EVENT_CONTROL_TRANSFER_DATA_RECEIVED:

            // This event indicates the data receive request associated with
            // the latest USB_DEVICE_ControlReceive() function was
            // completed. pData will be NULL. The application can either
            // acknowledge the received data or reject it by calling the 
            // USB_DEVICE_ControlStatus() function. 

            break;

        case USB_DEVICE_AUDIO_EVENT_CONTROL_SET_CUR:
            
            // This event indicates that the host is trying to set the
            // current setting attribute of a control. The data type will be
            // USB_DEVICE_AUDIO_EVENT_DATA_CONTROL_SET_CUR type.  The
            // application should identify the entity type based on the
            // entity ID. This mapping is application specific. The
            // following example assumes entity type to be a Feature Unit. 

            if(APP_EntityIdentify(((USB_DEVICE_AUDIO_EVENT_DATA_CONTROL_SET_CUR *)pData)->entityID) 
                    == APP_AUDIO_ENTITY_FEATURE_UNIT)
            {
                // The entity type is a feature unit. Type cast pData as
                // a USB_AUDIO_FEATURE_UNIT_CONTROL_REQUEST type and find
                // identify the control selector. This example shows the 
                // handling for VOLUME control 

                switch(((USB_AUDIO_FEATURE_UNIT_CONTROL_REQUEST *)pData)->controlSelector)
                {
                    case USB_AUDIO_VOLUME_CONTROL:
                        // This means the host is trying to set the volume.
                        // Use the USB_DEVICE_ControlReceive() function to
                        // receive the volume settings for each channel.

                        USB_DEVICE_ControlReceive(usbDeviceHandle, volumeSetting,
                                ((USB_AUDIO_FEATURE_UNIT_CONTROL_REQUEST *)pData)->wLength);
                    default:
                        // Only volume control is supported in this example.
                        // So everything else is stalled.
                        USB_DEVICE_ControlStatus(usbDeviceHandle, USB_DEVICE_CONTROL_STATUS_ERROR);
                }
            }
            break;

        case USB_DEVICE_AUDIO_EVENT_CONTROL_GET_CUR:
            
            // This event indicates that the host is trying to get the
            // current setting attribute of a control. The data type will be
            // USB_DEVICE_AUDIO_EVENT_DATA_CONTROL_SET_CUR type.  The
            // application should identify the entity type based on the
            // entity ID. This mapping is application specific. The
            // following example assumes entity type to be a Feature Unit. 

            if(APP_EntityIdentify(((USB_DEVICE_AUDIO_EVENT_DATA_CONTROL_SET_CUR *)pData)->entityID) 
                    == APP_AUDIO_ENTITY_FEATURE_UNIT)
            {
                // The entity type is a feature unit. Type cast pData as
                // a USB_AUDIO_FEATURE_UNIT_CONTROL_REQUEST type and find
                // identify the control selector. This example shows the 
                // handling for VOLUME control 

                switch(((USB_AUDIO_FEATURE_UNIT_CONTROL_REQUEST *)pData)->controlSelector)
                {
                    case USB_AUDIO_VOLUME_CONTROL:
                        // This means the host is trying to get the volume.
                        // Use the USB_DEVICE_ControlReceive() function to
                        // receive the volume settings for each channel.

                        USB_DEVICE_ControlSend(usbDeviceHandle, volumeSetting,
                                ((USB_AUDIO_FEATURE_UNIT_CONTROL_REQUEST *)pData)->wLength);
                    default:
                        // Only volume control is supported in this example.
                        // So everything else is stalled.
                        USB_DEVICE_ControlStatus(usbDeviceHandle, USB_DEVICE_CONTROL_STATUS_ERROR);
                }
            }
            break;
        
        case USB_DEVICE_AUDIO_EVENT_CONTROL_SET_MAX:
        case USB_DEVICE_AUDIO_EVENT_CONTROL_SET_MIN:
        case USB_DEVICE_AUDIO_EVENT_CONTROL_SET_RES:
        case USB_DEVICE_AUDIO_EVENT_CONTROL_SET_MEM:
        case USB_DEVICE_AUDIO_EVENT_CONTROL_GET_MAX:
        case USB_DEVICE_AUDIO_EVENT_CONTROL_GET_MIN:
        case USB_DEVICE_AUDIO_EVENT_CONTROL_GET_RES:
        case USB_DEVICE_AUDIO_EVENT_CONTROL_GET_MEM:
            // In this example these request are not supported and so are
            // stalled.
            USB_DEVICE_ControlStatus(usbDeviceHandle, USB_DEVICE_CONTROL_STATUS_ERROR);
            break;
        
        default:
            break;
    }
    
    return(USB_DEVICE_AUDIO_EVENT_RESPONSE_NONE);
}