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/* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* $Header$
*
*/
#include "stdafx.h"
#include "common/stream.h"
#include "sound/audiostream.h"
#include "sound/adpcm.h"
// Routines to convert 12 bit linear samples to the
// Dialogic or Oki ADPCM coding format aka VOX
class ADPCMInputStream : public AudioStream {
private:
bool _evenPos;
Common::SeekableReadStream *_stream;
typesADPCM _type;
uint32 _endpos;
struct adpcmStatus {
int16 last;
int16 stepIndex;
} _status;
int16 stepAdjust(byte);
int16 okiADPCMDecode(byte);
int16 imaADPCMDecode(byte);
int readOkiBuffer(int16 *buffer, const int numSamples);
int readIMABuffer(int16 *buffer, const int numSamples);
public:
ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size, typesADPCM type);
~ADPCMInputStream() {};
int readBuffer(int16 *buffer, const int numSamples);
bool endOfData() const { return (_stream->eos() || _stream->pos() >= _endpos); }
bool isStereo() const { return false; }
int getRate() const { return 22050; }
};
ADPCMInputStream::ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size, typesADPCM type)
: _stream(stream), _evenPos(true), _type(type) {
_status.last = 0;
_status.stepIndex = 0;
_endpos = stream->pos() + size;
}
int ADPCMInputStream::readBuffer(int16 *buffer, const int numSamples) {
switch (_type) {
case kADPCMOki:
return readOkiBuffer(buffer, numSamples);
break;
case kADPCMIma:
return readIMABuffer(buffer, numSamples);
break;
default:
error("Unsupported ADPCM encoding");
break;
}
return 0;
}
int ADPCMInputStream::readOkiBuffer(int16 *buffer, const int numSamples) {
int samples;
for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples++) {
// * 16 effectively converts 12-bit input to 16-bit output
if (_evenPos) {
buffer[samples] = okiADPCMDecode((_stream->readByte() >> 4) & 0x0f) * 16;
// Rewind back so we will reget byte later
_stream->seek(-1, SEEK_CUR);
} else {
buffer[samples] = okiADPCMDecode(_stream->readByte() & 0x0f) * 16;
}
_evenPos = !_evenPos;
}
return samples;
}
int ADPCMInputStream::readIMABuffer(int16 *buffer, const int numSamples) {
int samples;
for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples++) {
if (_evenPos) {
buffer[samples] = imaADPCMDecode((_stream->readByte() >> 4) & 0x0f);
// Rewind back so we will reget byte later
_stream->seek(-1, SEEK_CUR);
} else {
buffer[samples] = imaADPCMDecode(_stream->readByte() & 0x0f);
}
_evenPos = !_evenPos;
}
return samples;
}
// adjust the step for use on the next sample.
int16 ADPCMInputStream::stepAdjust(byte code) {
static const int16 adjusts[] = {-1, -1, -1, -1, 2, 4, 6, 8};
return adjusts[code & 0x07];
}
static const int16 okiStepSize[49] = {
16, 17, 19, 21, 23, 25, 28, 31,
34, 37, 41, 45, 50, 55, 60, 66,
73, 80, 88, 97, 107, 118, 130, 143,
157, 173, 190, 209, 230, 253, 279, 307,
337, 371, 408, 449, 494, 544, 598, 658,
724, 796, 876, 963, 1060, 1166, 1282, 1408,
1552
};
// Decode Linear to ADPCM
int16 ADPCMInputStream::okiADPCMDecode(byte code) {
int16 diff, E, SS, samp;
SS = okiStepSize[_status.stepIndex];
E = SS/8;
if (code & 0x01)
E += SS/4;
if (code & 0x02)
E += SS/2;
if (code & 0x04)
E += SS;
diff = (code & 0x08) ? -E : E;
samp = _status.last + diff;
// Clip the values to +/- 2^11 (supposed to be 12 bits)
if (samp > 2048)
samp = 2048;
if (samp < -2048)
samp = -2048;
_status.last = samp;
_status.stepIndex += stepAdjust(code);
if (_status.stepIndex < 0)
_status.stepIndex = 0;
if (_status.stepIndex > 48)
_status.stepIndex = 48;
return samp;
}
AudioStream *makeADPCMStream(Common::SeekableReadStream &stream, uint32 size, typesADPCM type) {
AudioStream *audioStream = new ADPCMInputStream(&stream, size, type);
return audioStream;
}
static const uint16 imaStepTable[89] = {
7, 8, 9, 10, 11, 12, 13, 14,
16, 17, 19, 21, 23, 25, 28, 31,
34, 37, 41, 45, 50, 55, 60, 66,
73, 80, 88, 97, 107, 118, 130, 143,
157, 173, 190, 209, 230, 253, 279, 307,
337, 371, 408, 449, 494, 544, 598, 658,
724, 796, 876, 963, 1060, 1166, 1282, 1411,
1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
7132, 7845, 8630, 9493,10442,11487,12635,13899,
15289,16818,18500,20350,22385,24623,27086,29794,
32767
};
int16 ADPCMInputStream::imaADPCMDecode(byte code) {
int32 diff, E, SS, samp;
SS = imaStepTable[_status.stepIndex];
E = SS/8;
if (code & 0x01)
E += SS/4;
if (code & 0x02)
E += SS/2;
if (code & 0x04)
E += SS;
diff = (code & 0x08) ? -E : E;
samp = _status.last + diff;
if (samp < -32768)
samp = -32768;
else if (samp > 32767)
samp = 32767;
_status.last = samp;
_status.stepIndex += stepAdjust(code);
if (_status.stepIndex < 0)
_status.stepIndex = 0;
if (_status.stepIndex > 88)
_status.stepIndex = 88;
return samp;
}
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