text: /*************************************************************************/
  /*  audio_driver_javascript.h                                            */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
  /*                                                                       */
  /* Permission is hereby granted, free of charge, to any person obtaining */
  /* a copy of this software and associated documentation files (the       */
  /* "Software"), to deal in the Software without restriction, including   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* The above copyright notice and this permission notice shall be        */
  /* included in all copies or substantial portions of the Software.       */
  /*                                                                       */
  /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
  /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
  /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #ifndef AUDIO_DRIVER_JAVASCRIPT_H
  #define AUDIO_DRIVER_JAVASCRIPT_H
  
  #include "core/os/mutex.h"
  #include "core/os/thread.h"
  #include "servers/audio_server.h"
  
  #include "godot_audio.h"
  
  class AudioDriverJavaScript : public AudioDriver {
  private:
  	struct AudioContext {
  		bool inited = false;
  		float output_latency = 0.0;
  		int state = -1;
  		int channel_count = 0;
  		int mix_rate = 0;
  	};
  	static AudioContext audio_context;
  
  	float *output_rb = nullptr;
  	float *input_rb = nullptr;
  
  	int buffer_length = 0;
  	int mix_rate = 0;
  	int channel_count = 0;
  
  	static void _state_change_callback(int p_state);
  	static void _latency_update_callback(float p_latency);
  
  	static AudioDriverJavaScript *singleton;
  
  protected:
  	void _audio_driver_process(int p_from = 0, int p_samples = 0);
  	void _audio_driver_capture(int p_from = 0, int p_samples = 0);
  	float *get_output_rb() const { return output_rb; }
  	float *get_input_rb() const { return input_rb; }
  
  	virtual Error create(int &p_buffer_samples, int p_channels) = 0;
  	virtual void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) = 0;
  	virtual void finish_driver() {}
  
  public:
  	static bool is_available();
  
  	virtual Error init() final;
  	virtual void start() final;
  	virtual void finish() final;
  
  	virtual float get_latency() override;
  	virtual int get_mix_rate() const override;
  	virtual SpeakerMode get_speaker_mode() const override;
  
  	virtual Error capture_start() override;
  	virtual Error capture_stop() override;
  
  	static void resume();
  
  	AudioDriverJavaScript() {}
  };
  
  #ifdef NO_THREADS
  class AudioDriverScriptProcessor : public AudioDriverJavaScript {
  private:
  	static void _process_callback();
  
  	static AudioDriverScriptProcessor *singleton;
  
  protected:
  	Error create(int &p_buffer_samples, int p_channels) override;
  	void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
  
  public:
  	virtual const char *get_name() const override { return "ScriptProcessor"; }
  
  	virtual void lock() override {}
  	virtual void unlock() override {}
  
  	AudioDriverScriptProcessor() { singleton = this; }
  };
  
  class AudioDriverWorklet : public AudioDriverJavaScript {
  private:
  	static void _process_callback(int p_pos, int p_samples);
  	static void _capture_callback(int p_pos, int p_samples);
  
  	static AudioDriverWorklet *singleton;
  
  protected:
  	virtual Error create(int &p_buffer_size, int p_output_channels) override;
  	virtual void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
  
  public:
  	virtual const char *get_name() const override { return "AudioWorklet"; }
  
  	virtual void lock() override {}
  	virtual void unlock() override {}
  
  	AudioDriverWorklet() { singleton = this; }
  };
  #else
  class AudioDriverWorklet : public AudioDriverJavaScript {
  private:
  	enum {
  		STATE_LOCK,
  		STATE_PROCESS,
  		STATE_SAMPLES_IN,
  		STATE_SAMPLES_OUT,
  		STATE_MAX,
  	};
  	Mutex mutex;
  	Thread thread;
  	bool quit = false;
  	int32_t state[STATE_MAX] = { 0 };
  
  	static void _audio_thread_func(void *p_data);
  
  protected:
  	virtual Error create(int &p_buffer_size, int p_output_channels) override;
  	virtual void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
  	virtual void finish_driver() override;
  
  public:
  	virtual const char *get_name() const override { return "AudioWorklet"; }
  
  	void lock() override;
  	void unlock() override;
  };
  #endif
  
  #endif
  