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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.
*
*/
#include "audio/decoders/xa.h"
#include "audio/audiostream.h"
#include "common/stream.h"
namespace Audio {
class XAStream : public Audio::RewindableAudioStream {
public:
XAStream(Common::SeekableReadStream *stream, int rate, DisposeAfterUse::Flag disposeAfterUse);
~XAStream();
bool isStereo() const { return false; }
bool endOfData() const { return _endOfData && _samplesRemaining == 0; }
int getRate() const { return _rate; }
int readBuffer(int16 *buffer, const int numSamples);
bool rewind();
private:
Common::SeekableReadStream *_stream;
DisposeAfterUse::Flag _disposeAfterUse;
void seekToPos(uint pos);
byte _predictor;
double _samples[28];
byte _samplesRemaining;
int _rate;
double _s1, _s2;
uint _loopPoint;
bool _endOfData;
};
XAStream::XAStream(Common::SeekableReadStream *stream, int rate, DisposeAfterUse::Flag disposeAfterUse)
: _stream(stream), _disposeAfterUse(disposeAfterUse) {
_samplesRemaining = 0;
_predictor = 0;
_s1 = _s2 = 0.0;
_rate = rate;
_loopPoint = 0;
_endOfData = false;
}
XAStream::~XAStream() {
if (_disposeAfterUse == DisposeAfterUse::YES)
delete _stream;
}
static const double s_xaDataTable[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 XAStream::readBuffer(int16 *buffer, const int numSamples) {
int32 samplesDecoded = 0;
for (int i = 28 - _samplesRemaining; i < 28 && samplesDecoded < numSamples; i++) {
_samples[i] = _samples[i] + _s1 * s_xaDataTable[_predictor][0] + _s2 * s_xaDataTable[_predictor][1];
_s2 = _s1;
_s1 = _samples[i];
int16 d = (int)(_samples[i] + 0.5);
buffer[samplesDecoded] = d;
samplesDecoded++;
_samplesRemaining--;
}
if (endOfData())
return samplesDecoded;
while (samplesDecoded < numSamples) {
byte i = 0;
_predictor = _stream->readByte();
byte shift = _predictor & 0xf;
_predictor >>= 4;
byte flags = _stream->readByte();
if (flags == 3) {
// Loop
seekToPos(_loopPoint);
continue;
} else if (flags == 6) {
// Set loop point
_loopPoint = _stream->pos() - 2;
} else if (flags == 7) {
// End of stream
_endOfData = true;
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_xaDataTable[_predictor][0] + _s2 * s_xaDataTable[_predictor][1];
_s2 = _s1;
_s1 = _samples[i];
int16 d = (int)(_samples[i] + 0.5);
buffer[samplesDecoded] = d;
samplesDecoded++;
}
if (i != 28)
_samplesRemaining = 28 - i;
if (_stream->pos() >= _stream->size())
_endOfData = true;
}
return samplesDecoded;
}
bool XAStream::rewind() {
seekToPos(0);
return true;
}
void XAStream::seekToPos(uint pos) {
_stream->seek(pos);
_samplesRemaining = 0;
_predictor = 0;
_s1 = _s2 = 0.0;
_endOfData = false;
}
RewindableAudioStream *makeXAStream(Common::SeekableReadStream *stream, int rate, DisposeAfterUse::Flag disposeAfterUse) {
return new XAStream(stream, rate, disposeAfterUse);
}
} // End of namespace Audio
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