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adpcm.h

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2005 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.
 *
 * $Header: /cvsroot/scummvm/scummvm/sound/adpcm.h,v 1.4.2.2 2005/10/21 02:25:20 sev Exp $
 *
 */

#ifndef SOUND_ADPCM_H
#define SOUND_ADPCM_H

#include "common/stdafx.h"
#include "common/scummsys.h"
#include "common/stream.h"
#include "sound/audiostream.h"

class AudioStream;

enum typesADPCM {
      kADPCMOki,
      kADPCMIma
};

// TODO: Switch from a SeekableReadStream to a plain ReadStream. This requires
// some internal refactoring but is definitely possible and will increase the
// flexibility of this code.
class ADPCMInputStream : public AudioStream {
private:
      Common::SeekableReadStream *_stream;
      uint32 _endpos;
      int _channels;
      typesADPCM _type;
      uint32 _blockAlign;

      struct adpcmStatus {
            int32 last;
            int32 stepIndex;
      } _status;

      int16 stepAdjust(byte);
      int16 decodeOKI(byte);
      int16 decodeMSIMA(byte);

public:
      ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size, typesADPCM type, int channels = 2, uint32 blockAlign = 0);
      ~ADPCMInputStream() {};

      int readBuffer(int16 *buffer, const int numSamples);
      int readBufferOKI(int16 *buffer, const int numSamples);
      int readBufferMSIMA1(int16 *buffer, const int numSamples);
      int readBufferMSIMA2(int16 *buffer, const int numSamples);

      bool endOfData() const { return (_stream->eos() || _stream->pos() >= _endpos); }
      bool isStereo() const   { return false; }
      int getRate() const     { return 22050; }
};

#endif

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