AUDIO: Expose ADPCM decoder internals via a new header

There are tons of ADPCM variants out there, and it is impractical to
stuff them all into a single adpcm.cpp file. By exposing the internals,
engines can implement their ADPCM decoder variants more easily.

1 files changed, 215 insertions, 0 deletions

diff --git a/audio/decoders/adpcm_intern.h b/audio/decoders/adpcm_intern.h
new file mode 100644
index 0000000000..8e092e67ad
--- /dev/null
+++ b/audio/decoders/adpcm_intern.h
@@ -0,0 +1,215 @@
+/* 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.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+/**
+ * Internal interfaces to the ADPCM encoders.
+ *
+ * These can be used to make custom ADPCM decoder subclasses,
+ * or to at least share some common data tables between various
+ * ADPCM decoder implementations.
+ */
+
+#ifndef SOUND_ADPCM_INTERN_H
+#define SOUND_ADPCM_INTERN_H
+
+#include "audio/audiostream.h"
+#include "common/endian.h"
+#include "common/stream.h"
+
+
+namespace Audio {
+
+class ADPCMStream : public RewindableAudioStream {
+protected:
+	Common::SeekableReadStream *_stream;
+	const DisposeAfterUse::Flag _disposeAfterUse;
+	const int32 _startpos;
+	const int32 _endpos;
+	const int _channels;
+	const uint32 _blockAlign;
+	uint32 _blockPos[2];
+	const int _rate;
+
+	struct {
+		// OKI/IMA
+		struct {
+			int32 last;
+			int32 stepIndex;
+		} ima_ch[2];
+	} _status;
+
+	virtual void reset();
+	int16 stepAdjust(byte);
+
+public:
+	ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign);
+	~ADPCMStream();
+
+	virtual bool endOfData() const { return (_stream->eos() || _stream->pos() >= _endpos); }
+	virtual bool isStereo() const	{ return _channels == 2; }
+	virtual int getRate() const	{ return _rate; }
+
+	virtual bool rewind();
+};
+
+class Oki_ADPCMStream : public ADPCMStream {
+public:
+	Oki_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign)
+		: ADPCMStream(stream, disposeAfterUse, size, rate, channels, blockAlign) {}
+
+	virtual int readBuffer(int16 *buffer, const int numSamples);
+
+protected:
+	int16 decodeOKI(byte);
+};
+
+class Ima_ADPCMStream : public ADPCMStream {
+protected:
+	int16 decodeIMA(byte code, int channel = 0); // Default to using the left channel/using one channel
+
+public:
+	Ima_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign)
+		: ADPCMStream(stream, disposeAfterUse, size, rate, channels, blockAlign) {
+		memset(&_status, 0, sizeof(_status));
+	}
+
+	virtual int readBuffer(int16 *buffer, const int numSamples);
+};
+
+class Apple_ADPCMStream : public Ima_ADPCMStream {
+protected:
+	// Apple QuickTime IMA ADPCM
+	int32 _streamPos[2];
+	int16 _buffer[2][2];
+	uint8 _chunkPos[2];
+
+	void reset() {
+		Ima_ADPCMStream::reset();
+		_chunkPos[0] = 0;
+		_chunkPos[1] = 0;
+		_streamPos[0] = 0;
+		_streamPos[1] = _blockAlign;
+	}
+
+public:
+	Apple_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign)
+		: Ima_ADPCMStream(stream, disposeAfterUse, size, rate, channels, blockAlign) {
+		_chunkPos[0] = 0;
+		_chunkPos[1] = 0;
+		_streamPos[0] = 0;
+		_streamPos[1] = _blockAlign;
+	}
+
+	virtual int readBuffer(int16 *buffer, const int numSamples);
+
+};
+
+class MSIma_ADPCMStream : public Ima_ADPCMStream {
+public:
+	MSIma_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign, bool invertSamples = false)
+		: Ima_ADPCMStream(stream, disposeAfterUse, size, rate, channels, blockAlign), _invertSamples(invertSamples) {
+		if (blockAlign == 0)
+			error("ADPCMStream(): blockAlign isn't specified for MS IMA ADPCM");
+	}
+
+	virtual int readBuffer(int16 *buffer, const int numSamples) {
+		if (_channels == 1)
+			return readBufferMSIMA1(buffer, numSamples);
+		else
+			return readBufferMSIMA2(buffer, numSamples);
+	}
+
+	int readBufferMSIMA1(int16 *buffer, const int numSamples);
+	int readBufferMSIMA2(int16 *buffer, const int numSamples);
+
+private:
+	bool _invertSamples;    // Some implementations invert the way samples are decoded
+};
+
+class MS_ADPCMStream : public ADPCMStream {
+protected:
+	struct ADPCMChannelStatus {
+		byte predictor;
+		int16 delta;
+		int16 coeff1;
+		int16 coeff2;
+		int16 sample1;
+		int16 sample2;
+	};
+
+	struct {
+		// MS ADPCM
+		ADPCMChannelStatus ch[2];
+	} _status;
+
+	void reset() {
+		ADPCMStream::reset();
+		memset(&_status, 0, sizeof(_status));
+	}
+
+public:
+	MS_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign)
+		: ADPCMStream(stream, disposeAfterUse, size, rate, channels, blockAlign) {
+		if (blockAlign == 0)
+			error("MS_ADPCMStream(): blockAlign isn't specified for MS ADPCM");
+		memset(&_status, 0, sizeof(_status));
+	}
+
+	virtual int readBuffer(int16 *buffer, const int numSamples);
+
+protected:
+	int16 decodeMS(ADPCMChannelStatus *c, byte);
+};
+
+// Duck DK3 IMA ADPCM Decoder
+// Based on FFmpeg's decoder and http://wiki.multimedia.cx/index.php?title=Duck_DK3_IMA_ADPCM
+
+class DK3_ADPCMStream : public Ima_ADPCMStream {
+protected:
+
+	void reset() {
+		Ima_ADPCMStream::reset();
+		_topNibble = false;
+	}
+
+public:
+	DK3_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign)
+		: Ima_ADPCMStream(stream, disposeAfterUse, size, rate, channels, blockAlign) {
+
+		// DK3 only works as a stereo stream
+		assert(channels == 2);
+		_topNibble = false;
+	}
+
+	virtual int readBuffer(int16 *buffer, const int numSamples);
+
+private:
+	byte _nibble, _lastByte;
+	bool _topNibble;
+};
+
+} // End of namespace Audio
+
+#endif