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audio/softsynth/pcspk.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef AUDIO_SOFTSYNTH_PCSPK_H
+#define AUDIO_SOFTSYNTH_PCSPK_H
+
+#include "audio/audiostream.h"
+#include "audio/mixer.h"
+#include "common/mutex.h"
+#include "common/queue.h"
+
+namespace Audio {
+
+class PCSpeakerStream;
+
+class PCSpeaker {
+public:
+	enum WaveForm {
+		kWaveFormSquare = 0,
+		kWaveFormSine,
+		kWaveFormSaw,
+		kWaveFormTriangle,
+		kWaveFormSilence
+	};
+
+public:
+	PCSpeaker();
+	~PCSpeaker();
+
+	bool init();
+	void quit();
+
+	/** Play a note for length ms.
+	 *
+	 *  If length is negative, play until told to stop.
+	 */
+	void play(WaveForm wave, int freq, int32 length);
+
+	/**
+	 * Queue the specified playback instruction. It will be executed when all
+	 * previously queued instructions have finished. Use this method for
+	 * playback of effects which require timing precision of less than a
+	 * millisecond.
+	 *
+	 * Calling this method will terminate any waveform started with the play
+	 * method. Calling the play method will terminate the active queued
+	 * instruction and clear the instruction queue.
+	 *
+	 * Use isPlaying to check if all queued instructions have finished playing.
+	 * This will return true even if the current instruction is "playing"
+	 * silence.
+	 *
+	 * @param wave The waveform to use. For PC speaker, use square wave or
+	 * silence.
+	 * @param freq The frequency (in Hertz) to play.
+	 * @param lengthus The length in microseconds for which to play the
+	 * waveform.
+	 */
+	void playQueue(WaveForm wave, float freq, uint32 lengthus);
+	/** Stop the currently playing note after delay ms. */
+	void stop(int32 delay = 0);
+
+	bool isPlaying() const;
+
+private:
+	PCSpeakerStream *_speakerStream;
+	SoundHandle _speakerHandle;
+};
+
+
+class PCSpeakerStream : public AudioStream {
+protected:
+	// PC speaker instruction: play this waveform at frequency x for y microseconds.
+	struct Command {
+		PCSpeaker::WaveForm waveForm;
+		float frequency;
+		uint32 length;
+
+		Command(PCSpeaker::WaveForm waveForm, float frequency, uint32 length);
+	};
+
+public:
+	PCSpeakerStream(int rate = 44100);
+	~PCSpeakerStream();
+
+	/** Play a note for length ms.
+	 *
+	 *  If length is negative, play until told to stop.
+	 */
+	void play(PCSpeaker::WaveForm wave, int freq, int32 length);
+	/**
+	 * Queue the specified playback instruction. It will be executed when all
+	 * previously queued instructions have finished. Use this method for
+	 * playback of effects which require timing precision of less than a
+	 * millisecond.
+	 *
+	 * Calling this method will terminate any waveform started with the play
+	 * method. Calling the play method will terminate the active queued
+	 * instruction and clear the instruction queue.
+	 *
+	 * Use isPlaying to check if all queued instructions have finished playing.
+	 * This will return true even if the current instruction is "playing"
+	 * silence.
+	 * 
+	 * @param wave The waveform to use. For PC speaker, use square wave or
+	 * silence.
+	 * @param freq The frequency (in Hertz) to play.
+	 * @param lengthus The length in microseconds for which to play the
+	 * waveform.
+	 */
+	void playQueue(PCSpeaker::WaveForm wave, float freq, uint32 lengthus);
+	/** Stop the currently playing note after delay ms. */
+	void stop(int32 delay = 0);
+
+	bool isPlaying() const;
+
+	int readBuffer(int16 *buffer, const int numSamples);
+
+	bool isStereo() const	{ return false; }
+	bool endOfData() const	{ return false; }
+	bool endOfStream() const { return false; }
+	int getRate() const	{ return _rate; }
+
+protected:
+	Common::Mutex _mutex;
+
+	int _rate;
+	PCSpeaker::WaveForm _wave;
+	bool _playForever;
+	uint32 _oscLength;
+	uint32 _oscSamples;
+	uint32 _remainingSamples;
+	uint32 _mixedSamples;
+	byte _volume;
+
+	// The queue of playback instructions.
+	Common::Queue<Command> *_commandQueue;
+	// True if a playback instruction is currently being executed. False if
+	// current playback was started by the play method (or if there is no
+	// playback at all).
+	bool _commandActive;
+
+	typedef int8 (*generatorFunc)(uint32, uint32);
+	static const generatorFunc generateWave[];
+
+	static int8 generateSquare(uint32 x, uint32 oscLength);
+	static int8 generateSine(uint32 x, uint32 oscLength);
+	static int8 generateSaw(uint32 x, uint32 oscLength);
+	static int8 generateTriangle(uint32 x, uint32 oscLength);
+	static int8 generateSilence(uint32 x, uint32 oscLength);
+};
+
+} // End of namespace Audio
+
+#endif // AUDIO_SOFTSYNTH_PCSPEAKER_H