part of wip xaudio2 wrapper

HRESULT _kit_audioX2_CreateVoice(_kit_audioX2_Engine* engine, const WAVEFORMATEX* source_format, unsigned int* index_p){
  HRESULT returnStatus=S_OK; int locked=0, slot=-1;
  _IF_ERROR(engine==NULL,E_INVALIDARG,;);
  _IF_ERROR(source_format==NULL,E_INVALIDARG,;);
  _IF_ERROR(index_p==NULL,E_INVALIDARG,;);
  EnterCriticalSection(&engine->lock); locked=1;

  //if no voices have been added, then allocate space for first pointer
  if(!engine->sources_len){
    engine->sources=(IXAudio2SourceVoice**)CoTaskMemRealloc(engine->sources, sizeof(IXAudio2SourceVoice*));
    _IF_ERROR(engine->sources==NULL,E_OUTOFMEMORY,;);
    engine->sources[0]=NULL;
    engine->sources_len=1;
  }

  //try to find first free space
  unsigned int sources_len=engine->sources_len;
  for(unsigned int i=0; i<sources_len; ++i){
    if(engine->sources[i]==NULL){
      returnStatus=engine->object->CreateSourceVoice(&engine->sources[i], source_format);
      _IF_GOTO_ERROR(FAILED(returnStatus),;);
      slot=i; break;
    }
  }

  //if no free space was found, append new voice to source voice list
  if(slot == -1){
    engine->sources=(IXAudio2SourceVoice**)CoTaskMemRealloc(engine->sources, sources_len*sizeof(IXAudio2SourceVoice*));
    _IF_ERROR(engine->sources==NULL,E_OUTOFMEMORY,;);
    returnStatus=engine->object->CreateSourceVoice(&engine->sources[sources_len], source_format);
    _IF_GOTO_ERROR(FAILED(returnStatus),;);
    slot=engine->sources_len++;
  }

  _error_:
  if((engine!=NULL) && locked) LeaveCriticalSection(&engine->lock);
  if(slot != -1) *index_p=slot;
  return returnStatus;
}


HRESULT _kit_audioX2_DestroyVoice(_kit_audioX2_Engine* engine, unsigned int index){
  HRESULT returnStatus=S_OK; int locked=0;
  _IF_ERROR(engine==NULL,E_INVALIDARG,;);
  EnterCriticalSection(&engine->lock); locked=1;
  _IF_ERROR(index>=engine->sources_len,E_INVALIDARG,;);
  _IF_GOTO_ERROR(engine->sources[index]==NULL,;);


  engine->sources[index]=NULL;

  //reallocate if index was the last element
  unsigned int last_source=engine->sources_len-1;
  if(index==last_source){
    if(last_source!=0){

    }
    --engine->sources_len;
  }

  _error_:
  if((engine!=NULL) && locked) LeaveCriticalSection(&engine->lock);
  return returnStatus;
}



//--//--//--//--//--//--//--//--//--//--//--//--//--//--//--//--//--//--//--//--//


HRESULT _kit_audioX2_New(_kit_audioX2_Engine** engine_p, const WAVEFORMATEX* source_format){
  HRESULT returnStatus=S_OK; ULONG numRefs=1; int critical_section=0;
  _IF_ERROR(engine_p==NULL,E_INVALIDARG,;);
  _IF_ERROR(source_format==NULL,E_INVALIDARG,;);
  //allocate memory for struct
  _kit_audioX2_Engine* engine=(_kit_audioX2_Engine*)CoTaskMemAlloc(sizeof(_kit_audioX2_Engine));
  _IF_ERROR(engine==NULL,E_OUTOFMEMORY,;);
  for(char i=0,*ch_p=(char*)engine; i<sizeof(_kit_audioX2_Engine); ++i) ch_p[i]=0;

  InitializeCriticalSection(&engine->lock); critical_section=1;

  //create xaudio2 object
  returnStatus=XAudio2Create(&engine->object, 0, XAUDIO2_DEFAULT_PROCESSOR);
  _IF_GOTO_ERROR(FAILED(returnStatus),;);

  //create mastering voice
  returnStatus=engine->object->CreateMasteringVoice(&engine->master);
  _IF_GOTO_ERROR(FAILED(returnStatus),;);

  //create the first source voice
  unsigned int slot;
  returnStatus=_kit_audioX2_AddVoice(engine, source_format, &slot);
  _IF_GOTO_ERROR(FAILED(returnStatus),;);

  _error_:
  if(SUCCEEDED(returnStatus)){
    *engine_p=engine;
  } else {
    if(engine != NULL){
      if(engine->sources != NULL){
        _KIT_COM_CALL_S(engine->sources[slot],DestroyVoice);
        CoTaskMemFree(engine->sources);
      }
      _KIT_COM_CALL_S(engine->master,DestroyVoice);
      _KIT_COM_RELEASE_S(engine->object);
      if(critical_section) DeleteCriticalSection(&engine->lock);
      CoTaskMemFree(engine); engine=NULL;
    }
  }
  return returnStatus;
}


HRESULT _kit_audioX2_Destroy(_kit_audioX2_Engine** engine_p){
  HRESULT returnStatus=S_OK; ULONG numRefs=1; int locked=0;
  _kit_audioX2_Engine* engine=NULL;
  _IF_ERROR(engine_p==NULL,E_INVALIDARG,;);
  _IF_ERROR((engine=*engine_p)==NULL,E_INVALIDARG,;);
  EnterCriticalSection(&engine->lock); locked=1;

  _KIT_COM_CALL_S(engine->object,StopEngine);

  unsigned int sources_len=engine->sources_len;
  for(unsigned int i=0; i<sources_len; ++i)
    _KIT_COM_CALL_S(engine->sources[i],DestroyVoice);

  _KIT_COM_CALL_S(engine->master,DestroyVoice);

  _KIT_COM_RELEASE_S(engine->object);
  LeaveCriticalSection(&engine->lock); locked=0;
  DeleteCriticalSection(&engine->lock);
  CoTaskMemFree(engine); *engine_p=NULL;

  _error_:
  if((engine!=NULL) && locked) LeaveCriticalSection(&engine->lock);
  return returnStatus;
}