Moved Paula and Infogrames to sound/mods/

svn-id: r25191

4 files changed, 869 insertions, 0 deletions

diff --git a/sound/mods/infogrames.cpp b/sound/mods/infogrames.cpp
new file mode 100644
index 0000000000..e5eda6e838
--- /dev/null
+++ b/sound/mods/infogrames.cpp
@@ -0,0 +1,458 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2007 The ScummVM project
+ *
+ * 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/mods/infogrames.h"
+#include "common/endian.h"
+
+namespace Audio {
+
+Infogrames::Instruments::Instruments() {
+	init();
+}
+
+Infogrames::Instruments::~Instruments() {
+	if (_sampleData)
+		delete[] _sampleData;
+}
+
+void Infogrames::Instruments::init() {
+	int i;
+
+	for (i = 0; i < 32; i++) {
+		_samples[i].data = 0;
+		_samples[i].dataRepeat = 0;
+		_samples[i].length = 0;
+		_samples[i].lengthRepeat = 0;
+	}
+	_count = 0;
+	_sampleData = 0;
+}
+
+bool Infogrames::Instruments::load(Common::SeekableReadStream &ins) {
+	int i;
+	uint32 fsize;
+	uint32 offset[32];
+	uint32 offsetRepeat[32];
+	uint32 dataOffset;
+
+	unload();
+
+	fsize = ins.readUint32BE();
+	dataOffset = fsize;
+	for (i = 0; (i < 32) && !ins.eos(); i++) {
+		offset[i] = ins.readUint32BE();
+		offsetRepeat[i] = ins.readUint32BE();
+		if ((offset[i] > fsize) || (offsetRepeat[i] > fsize) ||
+				(offset[i] < (ins.pos() + 4)) ||
+				(offsetRepeat[i] < (ins.pos() + 4))) {
+			// Definitely no real entry anymore
+			ins.seek(-8, SEEK_CUR);
+			break;
+		}
+
+		dataOffset = MIN(dataOffset, MIN(offset[i], offsetRepeat[i]));
+		ins.skip(4); // Unknown
+		_samples[i].length = ins.readUint16BE() * 2;
+		_samples[i].lengthRepeat = ins.readUint16BE() * 2;
+	}
+
+	if (dataOffset >= fsize)
+		return false;
+
+	_count = i;
+	_sampleData = new int8[fsize - dataOffset];
+	ins.seek(dataOffset + 4);
+	ins.read(_sampleData, fsize - dataOffset);
+
+	for (i--; i >= 0; i--) {
+		_samples[i].data = _sampleData + (offset[i] - dataOffset);
+		_samples[i].dataRepeat = _sampleData + (offsetRepeat[i] - dataOffset);
+	}
+
+	return true;
+}
+
+void Infogrames::Instruments::unload(void) {
+	if (_sampleData)
+		delete[] _sampleData;
+	init();
+}
+
+const uint8 Infogrames::tickCount[] =
+	{2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96};
+const uint16 Infogrames::periods[] =
+	{0x6ACC, 0x64CC, 0x5F25, 0x59CE, 0x54C3, 0x5003, 0x4B86, 0x4747, 0x4346,
+	 0x3F8B, 0x3BF3, 0x3892, 0x3568, 0x3269, 0x2F93, 0x2CEA, 0x2A66, 0x2801,
+	 0x2566, 0x23A5, 0x21AF, 0x1FC4, 0x1DFE, 0x1C4E, 0x1ABC, 0x1936, 0x17CC,
+	 0x1676, 0x1533, 0x1401, 0x12E4, 0x11D5, 0x10D4, 0x0FE3, 0x0EFE, 0x0E26, 
+	 0x0D5B, 0x0C9B, 0x0BE5, 0x0B3B, 0x0A9B, 0x0A02, 0x0972, 0x08E9, 0x0869,
+	 0x07F1, 0x077F, 0x0713, 0x06AD, 0x064D, 0x05F2, 0x059D, 0x054D, 0x0500,
+	 0x04B8, 0x0475, 0x0435, 0x03F8, 0x03BF, 0x038A, 0x0356, 0x0326, 0x02F9,
+	 0x02CF, 0x02A6, 0x0280, 0x025C, 0x023A, 0x021A, 0x01FC, 0x01E0, 0x01C5,
+	 0x01AB, 0x0193, 0x017D, 0x0167, 0x0153, 0x0140, 0x012E, 0x011D, 0x010D,
+	 0x00FE, 0x00F0, 0x00E2, 0x00D6, 0x00CA, 0x00BE, 0x00B4, 0x00AA, 0x00A0,
+	 0x0097, 0x008F, 0x0087, 0x007F, 0x0078, 0x0070, 0x0060, 0x0050, 0x0040,
+	 0x0030, 0x0020, 0x0010, 0x0000, 0x0000, 0x0020, 0x2020, 0x2020, 0x2020,
+	 0x2020, 0x3030, 0x3030, 0x3020, 0x2020, 0x2020, 0x2020, 0x2020, 0x2020,
+	 0x2020, 0x2020, 0x2020, 0x2090, 0x4040, 0x4040, 0x4040, 0x4040, 0x4040,
+	 0x4040, 0x4040, 0x400C, 0x0C0C, 0x0C0C, 0x0C0C, 0x0C0C, 0x0C40, 0x4040,
+	 0x4040, 0x4040, 0x0909, 0x0909, 0x0909, 0x0101, 0x0101, 0x0101, 0x0101,
+	 0x0101, 0x0101, 0x0101, 0x0101, 0x0101, 0x0101, 0x4040, 0x4040, 0x4040,
+	 0x0A0A, 0x0A0A, 0x0A0A, 0x0202, 0x0202, 0x0202, 0x0202, 0x0202, 0x0202,
+	 0x0202, 0x0202, 0x0202, 0x0202, 0x4040, 0x4040, 0x2000};
+
+Infogrames::Infogrames(Instruments &ins, bool stereo, int rate) :
+		Paula(stereo, rate, rate/80) {
+	_instruments = &ins;
+	_data = 0;
+	_repCount = -1;
+
+	reset();
+}
+
+Infogrames::~Infogrames() {
+	if (_data)
+		delete[] _data;
+}
+
+void Infogrames::init() {
+	int i;
+
+	_volume = 0;
+	_period = 0;
+	_sample = 0;
+	_speedCounter = _speed;
+
+	for (i = 0; i < 4; i++) {
+		_chn[i].cmds = 0;
+		_chn[i].cmdBlocks = 0;
+		_chn[i].volSlide.finetuneNeg = 0;
+		_chn[i].volSlide.finetunePos = 0;
+		_chn[i].volSlide.data = 0;
+		_chn[i].volSlide.amount = 0;
+		_chn[i].volSlide.dataOffset = 0;
+		_chn[i].volSlide.flags = 0;
+		_chn[i].volSlide.curDelay1 = 0;
+		_chn[i].volSlide.curDelay2 = 0;
+		_chn[i].periodSlide.finetuneNeg = 0;
+		_chn[i].periodSlide.finetunePos = 0;
+		_chn[i].periodSlide.data = 0;
+		_chn[i].periodSlide.amount = 0;
+		_chn[i].periodSlide.dataOffset = 0;
+		_chn[i].periodSlide.flags = 0;
+		_chn[i].periodSlide.curDelay1 = 0;
+		_chn[i].periodSlide.curDelay2 = 0;
+		_chn[i].period = 0;
+		_chn[i].flags = 0x81;
+		_chn[i].ticks = 0;
+		_chn[i].tickCount = 0;
+		_chn[i].periodMod = 0;
+	}
+
+	_end = _data == 0;
+}
+
+void Infogrames::reset() {
+	int i;
+
+	stopPlay();
+	init();
+
+	_volSlideBlocks = 0;
+	_periodSlideBlocks = 0;
+	_subSong = 0;
+	_cmdBlocks = 0;
+	_speedCounter = 0;
+	_speed = 0;
+
+	for (i = 0; i < 4; i++)
+		_chn[i].cmdBlockIndices = 0;
+}
+
+bool Infogrames::load(Common::SeekableReadStream &dum) {
+	int subSong = 0;
+	int i;
+	uint32 size;
+
+	size = dum.size();
+	if (size < 20)
+		return false;
+
+	_data = new uint8[size];
+	dum.seek(0);
+	dum.read(_data, size);
+
+	Common::MemoryReadStream dataStr(_data, size);
+
+	dataStr.seek(subSong * 2);
+	dataStr.seek(dataStr.readUint16BE());
+	_subSong = _data + dataStr.pos();
+	if (_subSong > (_data + size))
+		return false;
+
+	_speedCounter = dataStr.readUint16BE();
+	_speed = _speedCounter;
+	_volSlideBlocks = _subSong + dataStr.readUint16BE();
+	_periodSlideBlocks = _subSong + dataStr.readUint16BE();
+	for (i = 0; i < 4; i++) {
+		_chn[i].cmdBlockIndices = _subSong + dataStr.readUint16BE();
+		_chn[i].flags = 0x81;
+	}
+	_cmdBlocks = _data + dataStr.pos() + 2;
+
+	if ((_volSlideBlocks > (_data + size)) ||
+			(_periodSlideBlocks > (_data + size)) ||
+			(_chn[0].cmdBlockIndices > (_data + size)) ||
+			(_chn[1].cmdBlockIndices > (_data + size)) ||
+			(_chn[2].cmdBlockIndices > (_data + size)) ||
+			(_chn[3].cmdBlockIndices > (_data + size)) ||
+			(_cmdBlocks > (_data + size)))
+		return false;
+
+	_end = false;
+	_playing = true;
+	return true;
+}
+
+void Infogrames::unload(void) {
+	stopPlay();
+
+	if (_data)
+		delete[] _data;
+	_data = 0;
+
+	clearVoices();
+	reset();
+
+	_end = true;
+}
+
+void Infogrames::getNextSample(Channel &chn) {
+	byte *data;
+	byte cmdBlock;
+	uint16 cmd;
+	bool cont = false;
+
+	if (chn.flags & 64)
+		return;
+
+	if (chn.flags & 1) {
+		chn.flags &= ~1;
+		chn.cmdBlocks = chn.cmdBlockIndices;
+	} else {
+		chn.flags &= ~1;
+		if (_speedCounter == 0)
+			chn.ticks--;
+		if (chn.ticks != 0) {
+			_volume = MAX((int16) 0, tune(chn.volSlide, 0));
+			_period = tune(chn.periodSlide, chn.period);
+			return;
+		} else {
+			chn.ticks = chn.tickCount;
+			cont = true;
+		}
+	}
+
+	while (1) {
+		while (cont || ((cmdBlock = *chn.cmdBlocks) != 0xFF)) {
+			if (!cont) {
+				chn.cmdBlocks++;
+				chn.cmds = _subSong +
+					READ_BE_UINT16(_cmdBlocks + (cmdBlock * 2));
+			} else
+				cont = false;
+			while ((cmd = *chn.cmds) != 0xFF) {
+				chn.cmds++;
+				if (cmd & 128)
+				{
+					switch (cmd & 0xE0) {
+					case 0x80: // 100xxxxx - Set ticks
+						chn.ticks = tickCount[cmd & 0xF];
+						chn.tickCount = tickCount[cmd & 0xF];
+						break;
+					case 0xA0: // 101xxxxx - Set sample
+						_sample = cmd & 0x1F;
+						break;
+					case 0xC0: // 110xxxxx - Set volume slide/finetune
+						data = _volSlideBlocks + (cmd & 0x1F) * 13;
+						chn.volSlide.flags = (*data & 0x80) | 1;
+						chn.volSlide.amount = *data++ & 0x7F;
+						chn.volSlide.data = data;
+						chn.volSlide.dataOffset = 0;
+						chn.volSlide.finetunePos = 0;
+						chn.volSlide.finetuneNeg = 0;
+						chn.volSlide.curDelay1 = 0;
+						chn.volSlide.curDelay2 = 0;
+						break;
+					case 0xE0: // 111xxxxx - Extended
+						switch(cmd & 0x1F) {
+						case 0: // Set period modifier
+							chn.periodMod = (int8) *chn.cmds++;
+							break;
+						case 1: // Set continuous period slide
+							chn.periodSlide.data =
+								_periodSlideBlocks + *chn.cmds++ * 13 + 1;
+							chn.periodSlide.amount = 0;
+							chn.periodSlide.dataOffset = 0;
+							chn.periodSlide.finetunePos = 0;
+							chn.periodSlide.finetuneNeg = 0;
+							chn.periodSlide.curDelay1 = 0;
+							chn.periodSlide.curDelay2 = 0;
+							chn.periodSlide.flags = 0x81;
+							break;
+						case 2: // Set non-continuous period slide
+							chn.periodSlide.data =
+								_periodSlideBlocks + *chn.cmds++ * 13 + 1;
+							chn.periodSlide.amount = 0;
+							chn.periodSlide.dataOffset = 0;
+							chn.periodSlide.finetunePos = 0;
+							chn.periodSlide.finetuneNeg = 0;
+							chn.periodSlide.curDelay1 = 0;
+							chn.periodSlide.curDelay2 = 0;
+							chn.periodSlide.flags = 1;
+							break;
+						case 3: // NOP
+							break;
+						default:
+							warning("Unknown Infogrames command: %X", cmd);
+						}
+						break;
+					}
+				} else { // 0xxxxxxx - Set period
+					if (cmd != 0)
+						cmd += chn.periodMod;
+					chn.period = periods[cmd];
+					chn.volSlide.dataOffset = 0;
+					chn.volSlide.finetunePos = 0;
+					chn.volSlide.finetuneNeg = 0;
+					chn.volSlide.curDelay1 = 0;
+					chn.volSlide.curDelay2 = 0;
+					chn.volSlide.flags |= 1;
+					chn.volSlide.flags &= ~4;
+					chn.periodSlide.dataOffset = 0;
+					chn.periodSlide.finetunePos = 0;
+					chn.periodSlide.finetuneNeg = 0;
+					chn.periodSlide.curDelay1 = 0;
+					chn.periodSlide.curDelay2 = 0;
+					chn.periodSlide.flags |= 1;
+					chn.periodSlide.flags &= ~4;
+					_volume = MAX((int16) 0, tune(chn.volSlide, 0));
+					_period = tune(chn.periodSlide, chn.period);
+					return;
+				}
+			}
+		}
+		if (!(chn.flags & 32)) {
+			chn.flags |= 0x40;
+			_volume = 0;
+			return;
+		} else
+			chn.cmdBlocks = chn.cmdBlockIndices;
+	}
+}
+
+int16 Infogrames::tune(Slide &slide, int16 start) const {
+	byte *data;
+	uint8 off;
+
+	data = slide.data + slide.dataOffset;
+
+	if (slide.flags & 1)
+		slide.finetunePos += (int8) data[1];
+	slide.flags &= ~1;
+
+	start += slide.finetunePos - slide.finetuneNeg;
+	if (start < 0)
+		start = 0;
+
+	if (slide.flags & 4)
+		return start;
+
+	slide.curDelay1++;
+	if (slide.curDelay1 != data[2])
+		return start;
+	slide.curDelay2++;
+	slide.curDelay1 = 0;
+	if (slide.curDelay2 == data[0]) {
+		slide.curDelay2 = 0;
+		off = slide.dataOffset + 3;
+		if (off == 12) {
+			if (slide.flags == 0) {
+				slide.flags |= 4;
+				return start;
+			} else {
+				slide.curDelay2 = 0;
+				slide.finetuneNeg += slide.amount;
+				off = 3;
+			}
+		}
+		slide.dataOffset = off;
+	} 
+	slide.flags |= 1;
+	return start;
+}
+
+void Infogrames::interrupt() {
+	int chn;
+
+	if (!_data) {
+		clearVoices();
+		return;
+	}
+
+	_speedCounter--;
+	_sample = 0xFF;
+	for (chn = 0; chn < 4; chn++) {
+		_volume = 0;
+		_period = 0;
+		getNextSample(_chn[chn]);
+		_voice[chn].volume = _volume;
+		_voice[chn].period = _period;
+		if ((_sample != 0xFF) && (_sample < _instruments->_count)) {
+			_voice[chn].data = _instruments->_samples[_sample].data;
+			_voice[chn].length = _instruments->_samples[_sample].length;
+			_voice[chn].dataRepeat = _instruments->_samples[_sample].dataRepeat;
+			_voice[chn].lengthRepeat =
+				_instruments->_samples[_sample].lengthRepeat;
+			_voice[chn].offset = 0;
+			_sample = 0xFF;
+		}
+	}
+	if (_speedCounter == 0)
+		_speedCounter = _speed;
+
+	// End reached?
+	if ((_chn[0].flags & 64) && (_chn[1].flags & 64) &&
+			(_chn[2].flags & 64) && (_chn[3].flags & 64)) {
+		if (_repCount > 0) {
+			_repCount--;
+			init();
+		} else if (_repCount != -1) {
+			_end = true;
+			_playing = false;
+		}
+		else
+			init();
+	}
+}
+
+} // End of namespace Audio
diff --git a/sound/mods/infogrames.h b/sound/mods/infogrames.h
new file mode 100644
index 0000000000..78bc9efd82
--- /dev/null
+++ b/sound/mods/infogrames.h
@@ -0,0 +1,150 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2007 The ScummVM project
+ *
+ * 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_MODS_INFOGRAMES_H
+#define SOUND_MODS_INFOGRAMES_H
+
+#include "sound/mods/paula.h"
+#include "common/stream.h"
+#include "common/file.h"
+
+namespace Audio {
+
+/** A player for the Infogrames/RobHubbard2 format */
+class Infogrames : public Paula {
+public:
+	class Instruments {
+	public:
+		Instruments();
+		template<typename T> Instruments(T ins) {
+			init();
+			bool result = load(ins);
+			assert(result);
+		}
+		~Instruments();
+
+		bool load(Common::SeekableReadStream &ins);
+		bool load(const char *ins) {
+			Common::File f;
+
+			if (f.open(ins))
+				return load(f);
+			return false;
+		}
+		void unload(void);
+
+		uint8 getCount(void) const { return _count; }
+
+	protected:
+		struct Sample {
+			int8 *data;
+			int8 *dataRepeat;
+			uint32 length;
+			uint32 lengthRepeat;
+		} _samples[32];
+
+		uint8 _count;
+		int8 *_sampleData;
+
+		void init();
+
+		friend class Infogrames;
+	};
+
+	Infogrames(Instruments &ins, bool stereo = false, int rate = 44100);
+	~Infogrames();
+
+	Instruments *getInstruments(void) const { return _instruments; }
+	bool getRepeating(void) const { return _repCount != 0; }
+	void setRepeating (int32 repCount) { _repCount = repCount; }
+	virtual void startPlay(void) { _playing = true;}
+	virtual void stopPlay(void)
+	{
+		_mutex.lock();
+		_playing = false;
+		_mutex.unlock();
+	}
+	virtual void pausePlay(bool pause) { _playing = !pause; }
+
+	bool load(Common::SeekableReadStream &dum);
+	bool load(const char *dum) {
+		Common::File f;
+
+		if (f.open(dum))
+			return load(f);
+		return false;
+	}
+	void unload(void);
+	void restart(void) { if (_data) { stopPlay(); init(); startPlay(); } }
+
+protected:
+	Instruments *_instruments;
+
+	static const uint8 tickCount[];
+	static const uint16 periods[];
+	byte *_data;
+	int32 _repCount;
+
+	byte *_subSong;
+	byte *_cmdBlocks;
+	byte *_volSlideBlocks;
+	byte *_periodSlideBlocks;
+	uint8 _speedCounter;
+	uint8 _speed;
+
+	uint16 _volume;
+	int16 _period;
+	uint8 _sample;
+
+	struct Slide {
+		byte *data;
+		int8 amount;
+		uint8 dataOffset;
+		int16 finetuneNeg;
+		int16 finetunePos;
+		uint8 curDelay1;
+		uint8 curDelay2;
+		uint8 flags; // 0: Apply finetune modifier, 2: Don't slide, 7: Continuous
+	};
+	struct Channel {
+		byte *cmdBlockIndices;
+		byte *cmdBlocks;
+		byte *cmds;
+		uint8 ticks;
+		uint8 tickCount;
+		Slide volSlide;
+		Slide periodSlide;
+		int16 period;
+		int8 periodMod;
+		uint8 flags; // 0: Need init, 5: Loop cmdBlocks, 6: Ignore channel
+	} _chn[4];
+
+	void init(void);
+	void reset(void);
+	void getNextSample(Channel &chn);
+	int16 tune(Slide &slide, int16 start) const;
+	virtual void interrupt(void);
+};
+
+} // End of namespace Audio
+
+#endif
diff --git a/sound/mods/paula.cpp b/sound/mods/paula.cpp
new file mode 100644
index 0000000000..90d247096c
--- /dev/null
+++ b/sound/mods/paula.cpp
@@ -0,0 +1,167 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2007 The ScummVM project
+ *
+ * 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/mods/paula.h"
+
+namespace Audio {
+
+Paula::Paula(bool stereo, int rate, int interruptFreq) :
+		_stereo(stereo), _rate(rate), _intFreq(interruptFreq) {
+	_playing = false;
+
+	clearVoices();
+	_voice[0].panning = 63;
+	_voice[1].panning = 191;
+	_voice[2].panning = 191;
+	_voice[3].panning = 63;
+
+	if (_intFreq <= 0)
+		_intFreq = _rate;
+
+	_curInt = _intFreq;
+	_end = true;
+}
+
+Paula::~Paula() {
+}
+
+void Paula::clearVoice(byte voice) {
+	if (voice >= 4)
+		return;
+
+	_voice[voice].data = 0;
+	_voice[voice].dataRepeat = 0;
+	_voice[voice].length = 0;
+	_voice[voice].lengthRepeat = 0;
+	_voice[voice].period = 0;
+	_voice[voice].volume = 0;
+	_voice[voice].offset = 0;
+}
+
+int Paula::readBuffer(int16 *buffer, const int numSamples) {
+	int voice;
+	int samples;
+	int nSamples;
+	int sLen;
+	double frequency;
+	double rate;
+	double offset;
+	int16 *p;
+	int8 *data;
+
+	_mutex.lock();
+
+	memset(buffer, 0, numSamples * 2);
+	if (!_playing)
+	{
+		_mutex.unlock();
+		return numSamples;
+	}
+
+	samples = _stereo ? numSamples / 2 : numSamples;
+	while (samples > 0) {
+		if (_curInt == _intFreq) {
+			interrupt();
+			_curInt = 0;
+		}
+		nSamples = MIN(samples, _intFreq - _curInt);
+		for (voice = 0; voice < 4; voice++) {
+			if (!_voice[voice].data || (_voice[voice].period <= 0))
+				continue;
+
+			frequency = (7093789.2 / 2.0) / _voice[voice].period;
+			rate = frequency / _rate;
+			offset = _voice[voice].offset;
+			sLen = _voice[voice].length;
+			data = _voice[voice].data;
+			p = buffer;
+
+			_voice[voice].volume &= 0x3F;
+			if ((_voice[voice].lengthRepeat > 2) &&
+					((int)(offset + nSamples * rate) >= sLen)) {
+				int neededSamples = nSamples;
+
+				int end = (int)((sLen - offset) / rate);
+
+				for (int i = 0; i < end; i++)
+					mix(p, data[(int)(offset + rate * i)], voice);
+
+				_voice[voice].length = sLen = _voice[voice].lengthRepeat;
+				_voice[voice].data = data = _voice[voice].dataRepeat;
+				_voice[voice].offset = offset = 0;
+				neededSamples -= end;
+
+				while (neededSamples > 0) {
+					if (neededSamples >= (int) ((sLen - offset) / rate)) {
+						end = (int)((sLen - offset) / rate);
+
+						for (int i = 0; i < end; i++)
+							mix(p, data[(int)(offset + rate * i)], voice);
+
+						_voice[voice].data = data = _voice[voice].dataRepeat;
+						_voice[voice].length = sLen =
+							_voice[voice].lengthRepeat;
+						_voice[voice].offset = offset = 0;
+
+						neededSamples -= end;
+					} else {
+						for (int i = 0; i < neededSamples; i++)
+							mix(p, data[(int)(offset + rate * i)], voice);
+						_voice[voice].offset += rate * neededSamples;
+						if (ceil(_voice[voice].offset) >= sLen) {
+							_voice[voice].data = data = _voice[voice].dataRepeat;
+							_voice[voice].length = sLen =
+								_voice[voice].lengthRepeat;
+							_voice[voice].offset = offset = 0;
+						}
+						neededSamples = 0;
+					}
+				}
+			} else {
+				if (offset < sLen) {
+					if ((int)(offset + nSamples * rate) >= sLen) {
+						// The end of the sample is the limiting factor
+
+						int end = (int)((sLen - offset) / rate);
+						for (int i = 0; i < end; i++)
+							mix(p, data[(int)(offset + rate * i)], voice);
+						_voice[voice].offset = sLen;
+					} else {
+						// The requested number of samples is the limiting
+						// factor, not the sample
+
+						for (int i = 0; i < nSamples; i++)
+							mix(p, data[(int)(offset + rate * i)], voice);
+						_voice[voice].offset += rate * nSamples;
+					}
+				}
+			}
+		}
+		buffer += _stereo ? nSamples * 2 : nSamples;
+		_curInt += nSamples;
+		samples -= nSamples;
+	}
+	_mutex.unlock();
+	return numSamples;
+}
+
+} // End of namespace Audio
diff --git a/sound/mods/paula.h b/sound/mods/paula.h
new file mode 100644
index 0000000000..be85122635
--- /dev/null
+++ b/sound/mods/paula.h
@@ -0,0 +1,94 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2007 The ScummVM project
+ *
+ * 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_MODS_PAULA_H
+#define SOUND_MODS_PAULA_H
+
+#include "sound/audiostream.h"
+#include "common/mutex.h"
+
+namespace Audio {
+
+/**
+ * Emulation of the "Paula" Amiga music chip
+ * The interrupt frequency specifies the number of mixed wavesamples between
+ * calls of the interrupt method
+ */
+class Paula : public AudioStream {
+public:
+	Paula(bool stereo = false, int rate = 44100, int interruptFreq = 0);
+	~Paula();
+	
+	bool playing() const { return _playing; }
+	void setInterruptFreq(int freq) { _intFreq = freq; }
+	void setPanning(byte voice, byte panning)
+	{
+		if (voice < 4)
+			_voice[voice].panning = panning;
+	}
+	void clearVoice(byte voice);
+	void clearVoices() { int i; for (i = 0; i < 4; i++) clearVoice(i); }
+	virtual void startPlay(void) {}
+	virtual void stopPlay(void) {}
+	virtual void pausePlay(bool pause) {}
+
+// AudioStream API
+	int readBuffer(int16 *buffer, const int numSamples);
+	bool isStereo() const { return _stereo; }
+	bool endOfData() const { return _end; }
+	int getRate() const { return _rate; }
+
+protected:
+	struct Channel {
+		int8 *data;
+		int8 *dataRepeat;
+		uint32 length;
+		uint32 lengthRepeat;
+		int16 period;
+		byte volume;
+		double offset;
+		byte panning; // For stereo mixing: 0 = far left, 255 = far right
+	} _voice[4];
+
+	int _rate;
+	int _intFreq;
+	int _curInt;
+	bool _stereo;
+	bool _end;
+	bool _playing;
+	Common::Mutex _mutex;
+
+	void mix(int16 *&buf, int8 data, int voice) {
+		if (_stereo) {
+			*buf++ += (((int32) data) * _voice[voice].volume *
+				 (255 - _voice[voice].panning)) >> 7;
+			*buf++ += (((int32) data) * _voice[voice].volume *
+				 (_voice[voice].panning)) >> 7;
+		} else
+			*buf++ += _voice[voice].volume * data;
+	}
+	virtual void interrupt(void) {};
+};
+
+} // End of namespace Audio
+
+#endif