sfx_callback.cpp 2023-12-08

#include "_sfx.hpp"




//workaround for having _sfx_callback pause the device,
 //without having to call SDL_PauseAudioDevice inside the callback itself
int _sfx_pauseThread(void* data){
  sfx_class* sfx = (sfx_class*)data;
  if(sfx->isClosing()) return 0;
  sfx->lockDevice(true);

  //note: might cause problems if sfx is dangling for whatever reason
  try {
    sfx->lock(true);
  } catch(...){
    sfx->lockDevice(false);
    sfx->_getFadeInDelay() = 0xffffffff; //this should work, right?
    return -1;
  }

  //make sure current buffer finishes playing
  float bufferLengthSeconds = (float)sfx->getBufferLength() / sfx->getSampleRate();
  SDL_Delay(bufferLengthSeconds*1000 + 10); //+10ms just to be sure

  SDL_PauseAudioDevice(sfx->getDeviceID(),1);
  sfx->_setPlaying(false);

  sfx->lockDevice(false);
  sfx->lock(false);
  return 0;
}



void _sfx_callback(void* userdata, Uint8* _stream, int size){
  sfx_class*   sfx = (sfx_class*)userdata;
  sfx_f32s* stream = (sfx_f32s*)_stream;
  int          len = size/sizeof(sfx_f32s);

  size_t numTracks = sfx->getNumTracks();
  std::vector<sfx_track>& tracks = sfx->_getTracks();
  Uint64 timeStampEnd = sfx->getTimeStampEnd();

  sfx->_setTimeStampStart();
  SDL_memset(stream,0,size); //stream must be filled no matter what
  if(sfx->isClosing()) goto _skip_everything_; //if device is closing, exit early

  //if previous attempt to pause sfx failed, exit early
  try {
    sfx->lock(true);
  } catch(...){
    sfx->_getFadeInDelay() = 0xffffffff; //should work
    goto _skip_everything_;
  }
  if(sfx->_getFadeInDelay() == 0xffffffff) goto _unlock_device_;


  /**/
  for(size_t ti=0; ti<numTracks; ++ti){
    if(tracks[ti].pcm != nullptr){
      _sfx_mixTrack(tracks[ti],
                    timeStampEnd,
                    stream, len);
    }
  }
  /**/


  //apply linear fade to reduce popping when pausing and unpausing the device
  _sfx_globalFade(sfx, stream, len);

  _unlock_device_  : try { sfx->lock(false); } catch(...){} //just in case
  _skip_everything_: sfx->_setTimeStampEnd();
}