Moved Gob's square wave generator to sound/softsynth/pcspk.h

svn-id: r29564

2 files changed, 212 insertions, 0 deletions

diff --git a/sound/softsynth/pcspk.cpp b/sound/softsynth/pcspk.cpp
new file mode 100644
index 0000000000..444311c9a2
--- /dev/null
+++ b/sound/softsynth/pcspk.cpp
@@ -0,0 +1,126 @@
+/* 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 2
+* 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, write to the Free Software
+* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+*
+* $URL$
+* $Id$
+*
+*/
+
+#include "sound/softsynth/pcspk.h"
+
+namespace Audio {
+
+const PCSpeaker::generatorFunc PCSpeaker::generateWave[] =
+	{&PCSpeaker::generateSquare, &PCSpeaker::generateSine,
+	 &PCSpeaker::generateSaw,    &PCSpeaker::generateTriangle};
+
+PCSpeaker::PCSpeaker(int rate) {
+	_rate = rate;
+	_wave = kWaveFormSquare;
+	_playForever = false;
+	_oscLength = 0;
+	_oscSamples = 0;
+	_remainingSamples = 0;
+	_mixedSamples = 0;
+	_volume = 255;
+}
+
+PCSpeaker::~PCSpeaker() {
+}
+
+void PCSpeaker::play(WaveForm wave, int freq, int32 length) {
+	Common::StackLock lock(_mutex);
+
+	assert((wave >= kWaveFormSquare) && (wave <= kWaveFormTriangle));
+
+	_wave = wave;
+	_oscLength = _rate / freq;
+	_oscSamples = 0;
+	if (length == -1) {
+		_remainingSamples = 1;
+		_playForever = true;
+	} else {
+		_remainingSamples = (_rate * length) / 1000;
+		_playForever = false;
+	}
+	_mixedSamples = 0;
+}
+
+void PCSpeaker::stop(int32 delay) {
+	Common::StackLock lock(_mutex);
+
+	_remainingSamples = (_rate * delay) / 1000;
+	_playForever = false;
+}
+
+void PCSpeaker::setVolume(byte volume) {
+	_volume = volume;
+}
+
+int PCSpeaker::readBuffer(int16 *buffer, const int numSamples) {
+	Common::StackLock lock(_mutex);
+
+	int i;
+
+	for (i = 0; _remainingSamples && (i < numSamples); i++) {
+		buffer[i] = generateWave[_wave](_oscSamples, _oscLength) * _volume;
+		if (_oscSamples++ >= _oscLength)
+			_oscSamples = 0;
+		if (!_playForever)
+			_remainingSamples--;
+		_mixedSamples++;
+	}
+
+	// Clear the rest of the buffer
+	if (i < numSamples)
+		memset(buffer + i, 0, (numSamples - i) * sizeof(int16));
+
+	return numSamples;
+}
+
+int8 PCSpeaker::generateSquare(uint32 x, uint32 oscLength) {
+	return (x < (oscLength / 2)) ? 127 : -128;
+}
+
+int8 PCSpeaker::generateSine(uint32 x, uint32 oscLength) {
+	if (oscLength == 0)
+		return 0;
+
+	// TODO: Maybe using a look-up-table would be better?
+	return CLIP<int16>((int16) (128 * sin(2.0 * M_PI * x / oscLength)), -128, 127);
+}
+
+int8 PCSpeaker::generateSaw(uint32 x, uint32 oscLength) {
+	if (oscLength == 0)
+		return 0;
+
+	return ((x * (65536 / oscLength)) >> 8) - 128;
+}
+
+int8 PCSpeaker::generateTriangle(uint32 x, uint32 oscLength) {
+	if (oscLength == 0)
+		return 0;
+
+	int y = ((x * (65536 / (oscLength / 2))) >> 8) - 128;
+
+	return (x <= (oscLength / 2)) ? y : (256 - y);
+}
+
+} // End of namespace Audio
diff --git a/sound/softsynth/pcspk.h b/sound/softsynth/pcspk.h
new file mode 100644
index 0000000000..17eb6320e5
--- /dev/null
+++ b/sound/softsynth/pcspk.h
@@ -0,0 +1,86 @@
+/* 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 2
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ */
+
+#ifndef SOUND_SOFTSYNTH_PCSPK_H
+#define SOUND_SOFTSYNTH_PCSPK_H
+
+#include "sound/audiostream.h"
+#include "sound/mixer.h"
+#include "common/mutex.h"
+
+namespace Audio {
+
+class PCSpeaker : public AudioStream {
+public:
+	enum WaveForm {
+		kWaveFormSquare = 0,
+		kWaveFormSine,
+		kWaveFormSaw,
+		kWaveFormTriangle
+	};
+
+	PCSpeaker(int rate = 44100);
+	~PCSpeaker();
+
+	/** Play a note for length ms.
+	 *
+	 *  If length is negative, play until told to stop.
+	 */
+	void play(WaveForm wave, int freq, int32 length);
+	/** Stop the currently playing note after delay ms. */
+	void stop(int32 delay = 0);
+	/** Adjust the volume. */
+	void setVolume(byte volume);
+
+	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;
+	WaveForm _wave;
+	bool _playForever;
+	uint32 _oscLength;
+	uint32 _oscSamples;
+	uint32 _remainingSamples;
+	uint32 _mixedSamples;
+	byte _volume;
+
+	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);
+};
+
+} // End of namespace Audio
+
+#endif // SOUND_SOFTSYNTH_PCSPEAKER_H