C++ EventBase::size方法代码示例

void Top::processDsp()
{
  // check if there's anything to read
  int availableRead = jack_ringbuffer_read_space( guiToDsp );
  
  while ( availableRead >= sizeof(EventBase) )
  {
    jack_ringbuffer_peek( guiToDsp, (char*)guiToDspMem, sizeof(EventBase) );
    
    EventBase* e = static_cast<EventBase*>( guiToDspMem );
    
    // have to check the size against the event size (as opposed to the EventBase
    // size check earlier. Just because the write thread has written the EventBase
    // doesn't mean the whole event is written (2 memcpy writes when buffer wraps).
    // this check gaurantees that the whole event is available, and can be run
    if ( availableRead >= e->size() )
    {
      switch ( e->type() )
      {
        case EventBase::EVENT_BUFFER_TRANSFER:
        {
          if ( availableRead >= sizeof(EventBufferTransfer) )
          {
            EventBufferTransfer ev( (AudioBuffer*)0);
            jack_ringbuffer_read( guiToDsp, (char*)&ev, sizeof(EventBufferTransfer) );
            
            // pass the pointer to DSP
            dsp->setBuffer( ev.audioBufferPtr );
          }
          break;
        }
      }
    }
    // update available read, and loop over events
    availableRead = jack_ringbuffer_read_space(guiToDsp);
  }
}

// GUI thread calls this function periodically to update itself
void Top::processGui()
{
  // check if there's anything to read
  int availableRead = jack_ringbuffer_read_space(dspToGui);
  
  while ( availableRead >= sizeof(EventBase) )
  {
    jack_ringbuffer_peek( dspToGui, (char*)dspToGuiMem, sizeof(EventBase) );
    
    EventBase* e = static_cast<EventBase*>( dspToGuiMem );
    
    // again, have to check in case buffer is wrapping, and thread gets paused
    // inbetween the two memcpy calls, leaving a possible non-full event
    if ( availableRead >= e->size() )
    {
      switch ( e->type() )
      {
        case EventBase::EVENT_BUFFER_TRANSFER:
        {
          // create an empty of this event type
          EventBufferTransfer ev( (AudioBuffer*)0 );
          
          // read the event from the buffer
          jack_ringbuffer_read( dspToGui, (char*)&ev, sizeof(ev) );
          
          stringstream s;
          s << "GUI: Deleting AudioBuffer instance " << ev.audioBufferPtr->getID() << "  Addr: "
            << ev.audioBufferPtr;
          gui->printTextView( true, s.str() );
          
          AudioBuffer* tmp = ev.audioBufferPtr;
          cout << "Top deleting DSP audioBuffer  Addr: " << tmp << endl;
          
          
          // do the action: de-allocate buffer
          delete tmp;
          
          break;
        }
        case EventBase::EVENT_GUI_PRINT:
        {
          // create an empty of this event type
          EventGuiPrint ev;
          
          // read the event from the buffer
          jack_ringbuffer_read( dspToGui, (char*)&ev, ev.size() );
          
          // do the action: print it
          gui->printTextView( false, ev.getMessage() );
          
          break;
        }
        case EventBase::EVENT_PLAYBACK_POSITION:
        {
          // create an empty of this event type
          EventPlaybackPosition ev;
          
          // read the event from the buffer
          jack_ringbuffer_read( dspToGui, (char*)&ev, sizeof(ev) );
          
          // do the action: set the playback position
          gui->getWaveview()->setPlaybackPosition( ev.position );
          
          break;
        }
        default:
        {
          cout << "Top::processGUI() Recieved unknown event type " << e->type() << endl;
        }
      } // switch
    } // if ( available >= e->size() )
    else
    {
      // return if the EventBase was written but the whole event was not. This 
      // breaks out of the while loop, and the EventBase which is still in the
      // ringbuffer will be read on the next call of this function
      return;
    }
    // update available read, and see if there's more events 
    availableRead = jack_ringbuffer_read_space( dspToGui );
  }
}