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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 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 "audio/decoders/vag.h"
#include "audio/audiostream.h"
#include "common/stream.h"
namespace Audio {
class VagStream : public Audio::RewindableAudioStream {
public:
VagStream(Common::SeekableReadStream *stream, int rate);
~VagStream();
bool isStereo() const { return false; }
bool endOfData() const { return _stream->pos() == _stream->size(); }
int getRate() const { return _rate; }
int readBuffer(int16 *buffer, const int numSamples);
bool rewind();
private:
Common::SeekableReadStream *_stream;
byte _predictor;
double _samples[28];
byte _samplesRemaining;
int _rate;
double _s1, _s2;
};
VagStream::VagStream(Common::SeekableReadStream *stream, int rate) : _stream(stream) {
_samplesRemaining = 0;
_predictor = 0;
_s1 = _s2 = 0.0;
_rate = rate;
}
VagStream::~VagStream() {
delete _stream;
}
static const double s_vagDataTable[5][2] =
{
{ 0.0, 0.0 },
{ 60.0 / 64.0, 0.0 },
{ 115.0 / 64.0, -52.0 / 64.0 },
{ 98.0 / 64.0, -55.0 / 64.0 },
{ 122.0 / 64.0, -60.0 / 64.0 }
};
int VagStream::readBuffer(int16 *buffer, const int numSamples) {
int32 samplesDecoded = 0;
if (_samplesRemaining) {
byte i = 0;
for (i = 28 - _samplesRemaining; i < 28 && samplesDecoded < numSamples; i++) {
_samples[i] = _samples[i] + _s1 * s_vagDataTable[_predictor][0] + _s2 * s_vagDataTable[_predictor][1];
_s2 = _s1;
_s1 = _samples[i];
int16 d = (int) (_samples[i] + 0.5);
buffer[samplesDecoded] = d;
samplesDecoded++;
}
#if 0
assert(i == 28); // We're screwed if this fails :P
#endif
// This might mean the file is corrupted, or that the stream has
// been closed.
if (i != 28) return 0;
_samplesRemaining = 0;
}
while (samplesDecoded < numSamples) {
byte i = 0;
_predictor = _stream->readByte();
byte shift = _predictor & 0xf;
_predictor >>= 4;
if (_stream->readByte() == 7)
return samplesDecoded;
for (i = 0; i < 28; i += 2) {
byte d = _stream->readByte();
int16 s = (d & 0xf) << 12;
if (s & 0x8000)
s |= 0xffff0000;
_samples[i] = (double)(s >> shift);
s = (d & 0xf0) << 8;
if (s & 0x8000)
s |= 0xffff0000;
_samples[i + 1] = (double)(s >> shift);
}
for (i = 0; i < 28 && samplesDecoded < numSamples; i++) {
_samples[i] = _samples[i] + _s1 * s_vagDataTable[_predictor][0] + _s2 * s_vagDataTable[_predictor][1];
_s2 = _s1;
_s1 = _samples[i];
int16 d = (int) (_samples[i] + 0.5);
buffer[samplesDecoded] = d;
samplesDecoded++;
}
if (i != 27)
_samplesRemaining = 28 - i;
}
return samplesDecoded;
}
bool VagStream::rewind() {
_stream->seek(0);
_samplesRemaining = 0;
_predictor = 0;
_s1 = _s2 = 0.0;
return true;
}
RewindableAudioStream *makeVagStream(Common::SeekableReadStream *stream, int rate) {
return new VagStream(stream, rate);
}
}
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