aboutsummaryrefslogtreecommitdiff
path: root/sound/adpcm.cpp
blob: ef8bb50c988f9701922d277174ba82da50aba29f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
/* 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 "common/endian.h"

#include "sound/adpcm.h"
#include "sound/audiostream.h"


namespace Audio {

class ADPCMInputStream : public RewindableAudioStream {
private:
	Common::SeekableReadStream *_stream;
	bool _disposeAfterUse;
	int32 _startpos;
	int32 _endpos;
	int _channels;
	typesADPCM _type;
	uint32 _blockAlign;
	uint32 _blockPos[2];
	uint8 _chunkPos;
	uint16 _chunkData;
	int _blockLen;
	int _rate;

	struct ADPCMChannelStatus {
		byte predictor;
		int16 delta;
		int16 coeff1;
		int16 coeff2;
		int16 sample1;
		int16 sample2;
	};

	struct adpcmStatus {
		// OKI/IMA
		struct {
			int32 last;
			int32 stepIndex;
		} ima_ch[2];

		// Apple QuickTime IMA ADPCM
		int32 streamPos[2];

		// MS ADPCM
		ADPCMChannelStatus ch[2];

		// Tinsel
		double predictor;
		double K0, K1;
		double d0, d1;
	} _status;

	void reset();
	int16 stepAdjust(byte);
	int16 decodeOKI(byte);
	int16 decodeIMA(byte code, int channel = 0); // Default to using the left channel/using one channel
	int16 decodeMS(ADPCMChannelStatus *c, byte);
	int16 decodeTinsel(int16, double);

public:
	ADPCMInputStream(Common::SeekableReadStream *stream, bool disposeAfterUse, uint32 size, typesADPCM type, int rate, int channels, uint32 blockAlign);
	~ADPCMInputStream();

	int readBuffer(int16 *buffer, const int numSamples);
	int readBufferOKI(int16 *buffer, const int numSamples);
	int readBufferIMA(int16 *buffer, const int numSamples);
	int readBufferMSIMA1(int16 *buffer, const int numSamples);
	int readBufferMSIMA2(int16 *buffer, const int numSamples);
	int readBufferMS(int channels, int16 *buffer, const int numSamples);
	void readBufferTinselHeader();
	int readBufferTinsel4(int channels, int16 *buffer, const int numSamples);
	int readBufferTinsel6(int channels, int16 *buffer, const int numSamples);
	int readBufferTinsel8(int channels, int16 *buffer, const int numSamples);
	int readBufferApple(int16 *buffer, const int numSamples);

	bool endOfData() const { return (_stream->eos() || _stream->pos() >= _endpos); }
	bool isStereo() const	{ return _channels == 2; }
	int getRate() const	{ return _rate; }

	bool rewind();
};

// Routines to convert 12 bit linear samples to the
// Dialogic or Oki ADPCM coding format aka VOX.
// See also <http://www.comptek.ru/telephony/tnotes/tt1-13.html>
//
// IMA ADPCM support is based on
//   <http://wiki.multimedia.cx/index.php?title=IMA_ADPCM>
//
// In addition, also MS IMA ADPCM is supported. See
//   <http://wiki.multimedia.cx/index.php?title=Microsoft_IMA_ADPCM>.

ADPCMInputStream::ADPCMInputStream(Common::SeekableReadStream *stream, bool disposeAfterUse, uint32 size, typesADPCM type, int rate, int channels, uint32 blockAlign)
	: _stream(stream), _disposeAfterUse(disposeAfterUse), _channels(channels), _type(type), _blockAlign(blockAlign), _rate(rate) {

	if (type == kADPCMMSIma && blockAlign == 0)
		error("ADPCMInputStream(): blockAlign isn't specified for MS IMA ADPCM");
	if (type == kADPCMMS && blockAlign == 0)
		error("ADPCMInputStream(): blockAlign isn't specified for MS ADPCM");

	if (type == kADPCMTinsel4 && blockAlign == 0)
		error("ADPCMInputStream(): blockAlign isn't specified for Tinsel 4-bit ADPCM");
	if (type == kADPCMTinsel6 && blockAlign == 0)
		error("ADPCMInputStream(): blockAlign isn't specified for Tinsel 6-bit ADPCM");
	if (type == kADPCMTinsel8 && blockAlign == 0)
		error("ADPCMInputStream(): blockAlign isn't specified for Tinsel 8-bit ADPCM");

	if (type == kADPCMTinsel4 && channels != 1)
		error("ADPCMInputStream(): Tinsel 4-bit ADPCM only supports mono");
	if (type == kADPCMTinsel6 && channels != 1)
		error("ADPCMInputStream(): Tinsel 6-bit ADPCM only supports mono");
	if (type == kADPCMTinsel8 && channels != 1)
		error("ADPCMInputStream(): Tinsel 8-bit ADPCM only supports mono");

	_startpos = stream->pos();
	_endpos = _startpos + size;
	reset();
}

ADPCMInputStream::~ADPCMInputStream() {
	if (_disposeAfterUse)
		delete _stream;
}

void ADPCMInputStream::reset() {
	memset(&_status, 0, sizeof(_status));
	_blockLen = 0;
	_blockPos[0] = _blockPos[1] = _blockAlign; // To make sure first header is read
	_status.streamPos[0] = 0;
	_status.streamPos[1] = _blockAlign;
	_chunkPos = 0;
}

bool ADPCMInputStream::rewind() {
	// TODO: Error checking.
	reset();
	_stream->seek(_startpos);
	return true;
}

int ADPCMInputStream::readBuffer(int16 *buffer, const int numSamples) {
	int samplesDecoded = 0;
	switch (_type) {
	case kADPCMOki:
		samplesDecoded = readBufferOKI(buffer, numSamples);
		break;
	case kADPCMMSIma:
		if (_channels == 1)
			samplesDecoded = readBufferMSIMA1(buffer, numSamples);
		else
			samplesDecoded = readBufferMSIMA2(buffer, numSamples);
		break;
	case kADPCMMS:
		samplesDecoded = readBufferMS(_channels, buffer, numSamples);
		break;
	case kADPCMTinsel4:
		samplesDecoded = readBufferTinsel4(_channels, buffer, numSamples);
		break;
	case kADPCMTinsel6:
		samplesDecoded = readBufferTinsel6(_channels, buffer, numSamples);
		break;
	case kADPCMTinsel8:
		samplesDecoded = readBufferTinsel8(_channels, buffer, numSamples);
		break;
	case kADPCMIma:
		samplesDecoded = readBufferIMA(buffer, numSamples);
		break;
	case kADPCMApple:
		samplesDecoded = readBufferApple(buffer, numSamples);
		break;
	default:
		error("Unsupported ADPCM encoding");
		break;
	}

	return samplesDecoded;
}

int ADPCMInputStream::readBufferOKI(int16 *buffer, const int numSamples) {
	int samples;
	byte data;

	assert(numSamples % 2 == 0);

	for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples += 2) {
		data = _stream->readByte();
		buffer[samples] = decodeOKI((data >> 4) & 0x0f);
		buffer[samples + 1] = decodeOKI(data & 0x0f);
	}
	return samples;
}

int ADPCMInputStream::readBufferIMA(int16 *buffer, const int numSamples) {
	int samples;
	byte data;

	assert(numSamples % 2 == 0);

	for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples += 2) {
		data = _stream->readByte();
		buffer[samples] = decodeIMA((data >> 4) & 0x0f);
		buffer[samples + 1] = decodeIMA(data & 0x0f, _channels == 2 ? 1 : 0);
	}
	return samples;
}

int ADPCMInputStream::readBufferApple(int16 *buffer, const int numSamples) {
	// Need to write 2 samples per channel
	assert(numSamples % (2 * _channels) == 0);

	// Current sample positions
	int    samples[2] = {   0,    0};
	// Current data bytes
	byte      data[2] = {   0,    0};
	// Current nibble selectors
	bool lowNibble[2] = {true, true};

	// Number of samples per channel
	int chanSamples = numSamples / _channels;

	for (int i = 0; i < _channels; i++) {
		_stream->seek(_status.streamPos[i]);

		while ((samples[i] < chanSamples) &&
		       // Last byte read and a new one needed
		       !((_stream->eos() || (_stream->pos() >= _endpos)) && lowNibble[i])) {

			if (_blockPos[i] == _blockAlign) {
				// 2 byte header per block
				uint16 temp = _stream->readUint16BE();

				// First 9 bits are the upper bits of the predictor
				_status.ima_ch[i].last      = (int16) (temp & 0xFF80);
				// Lower 7 bits are the step index
				_status.ima_ch[i].stepIndex =          temp & 0x007F;

				// Clip the step index
				_status.ima_ch[i].stepIndex = CLIP<int32>(_status.ima_ch[i].stepIndex, 0, 88);

				_blockPos[i] = 2;
			}

			// First decode the lower nibble, then the upper
			if (lowNibble[i])
				data[i] = _stream->readByte();

			int16 sample;
			if (lowNibble[i])
				sample = decodeIMA(data[i] &  0x0F, i);
			else
				sample = decodeIMA(data[i] >>    4, i);

			// The original is interleaved block-wise, we want it sample-wise
			buffer[_channels * samples[i] + i] = sample;

			samples[i]++;

			// Different nibble
			lowNibble[i] = !lowNibble[i];

			// We're about to decode a new lower nibble again, so advance the block position
			if (lowNibble[i])
				_blockPos[i]++;

			if (_channels == 2)
				if (_blockPos[i] == _blockAlign)
					// We're at the end of the block.
					// Since the channels are interleaved, skip the next block
					_stream->skip(MIN<uint32>(_blockAlign, _endpos - _stream->pos()));

			_status.streamPos[i] = _stream->pos();
		}
	}

	return samples[0] + samples[1];
}

int ADPCMInputStream::readBufferMSIMA1(int16 *buffer, const int numSamples) {
	int samples = 0;
	byte data;

	assert(numSamples % 2 == 0);

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			// read block header
			_status.ima_ch[0].last = _stream->readSint16LE();
			_status.ima_ch[0].stepIndex = _stream->readSint16LE();
			_blockPos[0] = 4;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples += 2) {
			data = _stream->readByte();
			_blockPos[0]++;
			buffer[samples] = decodeIMA(data & 0x0f);
			buffer[samples + 1] = decodeIMA((data >> 4) & 0x0f);
		}
	}
	return samples;
}


// Microsoft as usual tries to implement it differently. This method
// is used for stereo data.
int ADPCMInputStream::readBufferMSIMA2(int16 *buffer, const int numSamples) {
	int samples;
	uint32 data;
	int nibble;
	byte k;

	for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos;) {
		for (int channel = 0; channel < 2; channel++) {
			data = _stream->readUint32LE();

			for (nibble = 0; nibble < 8; nibble++) {
				k = ((data & 0xf0000000) >> 28);
				buffer[samples + channel + nibble * 2] = decodeIMA(k);
				data <<= 4;
			}
		}
		samples += 16;
	}
	return samples;
}

static const int MSADPCMAdaptCoeff1[] = {
	256, 512, 0, 192, 240, 460, 392
};

static const int MSADPCMAdaptCoeff2[] = {
	0, -256, 0, 64, 0, -208, -232
};

int ADPCMInputStream::readBufferMS(int channels, int16 *buffer, const int numSamples) {
	int samples;
	byte data;
	int i = 0;

	samples = 0;

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			// read block header
			for (i = 0; i < channels; i++) {
				_status.ch[i].predictor = CLIP(_stream->readByte(), (byte)0, (byte)6);
				_status.ch[i].coeff1 = MSADPCMAdaptCoeff1[_status.ch[i].predictor];
				_status.ch[i].coeff2 = MSADPCMAdaptCoeff2[_status.ch[i].predictor];
			}

			for (i = 0; i < channels; i++)
				_status.ch[i].delta = _stream->readSint16LE();

			for (i = 0; i < channels; i++)
				_status.ch[i].sample1 = _stream->readSint16LE();

			for (i = 0; i < channels; i++)
				buffer[samples++] = _status.ch[i].sample2 = _stream->readSint16LE();

			for (i = 0; i < channels; i++)
				buffer[samples++] = _status.ch[i].sample1;

			_blockPos[0] = channels * 7;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples += 2) {
			data = _stream->readByte();
			_blockPos[0]++;
			buffer[samples] = decodeMS(&_status.ch[0], (data >> 4) & 0x0f);
			buffer[samples + 1] = decodeMS(&_status.ch[channels - 1], data & 0x0f);
		}
	}

	return samples;
}

static const double TinselFilterTable[4][2] = {
	{0, 0 },
	{0.9375, 0},
	{1.796875, -0.8125},
	{1.53125, -0.859375}
};

void ADPCMInputStream::readBufferTinselHeader() {
	uint8 start = _stream->readByte();
	uint8 filterVal = (start & 0xC0) >> 6;

	if ((start & 0x20) != 0) {
		//Lower 6 bit are negative

		// Negate
		start = ~(start | 0xC0) + 1;

		_status.predictor = 1 << start;
	} else {
		// Lower 6 bit are positive

		// Truncate
		start &= 0x1F;

		_status.predictor = ((double) 1.0) / (1 << start);
	}

	_status.K0 = TinselFilterTable[filterVal][0];
	_status.K1 = TinselFilterTable[filterVal][1];
}

int ADPCMInputStream::readBufferTinsel4(int channels, int16 *buffer, const int numSamples) {
	int samples;
	uint16 data;
	const double eVal = 1.142822265;

	samples = 0;

	assert(numSamples % 2 == 0);

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			readBufferTinselHeader();
			_blockPos[0] = 0;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples += 2, _blockPos[0]++) {
			// Read 1 byte = 8 bits = two 4 bit blocks
			data = _stream->readByte();
			buffer[samples] = decodeTinsel((data << 8) & 0xF000, eVal);
			buffer[samples+1] = decodeTinsel((data << 12) & 0xF000, eVal);
		}
	}

	return samples;
}

int ADPCMInputStream::readBufferTinsel6(int channels, int16 *buffer, const int numSamples) {
	int samples;
	const double eVal = 1.032226562;

	samples = 0;

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			readBufferTinselHeader();
			_blockPos[0] = 0;
			_chunkPos = 0;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples++, _chunkPos = (_chunkPos + 1) % 4) {

			switch (_chunkPos) {
			case 0:
				_chunkData = _stream->readByte();
				buffer[samples] = decodeTinsel((_chunkData << 8) & 0xFC00, eVal);
				break;
			case 1:
				_chunkData = (_chunkData << 8) | (_stream->readByte());
				buffer[samples] = decodeTinsel((_chunkData << 6) & 0xFC00, eVal);
				_blockPos[0]++;
				break;
			case 2:
				_chunkData = (_chunkData << 8) | (_stream->readByte());
				buffer[samples] = decodeTinsel((_chunkData << 4) & 0xFC00, eVal);
				_blockPos[0]++;
				break;
			case 3:
				_chunkData = (_chunkData << 8);
				buffer[samples] = decodeTinsel((_chunkData << 2) & 0xFC00, eVal);
				_blockPos[0]++;
				break;
			}

		}

	}

	return samples;
}

int ADPCMInputStream::readBufferTinsel8(int channels, int16 *buffer, const int numSamples) {
	int samples;
	byte data;
	const double eVal = 1.007843258;

	samples = 0;

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			readBufferTinselHeader();
			_blockPos[0] = 0;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples++, _blockPos[0]++) {
			// Read 1 byte = 8 bits = one 8 bit block
			data = _stream->readByte();
			buffer[samples] = decodeTinsel(data << 8, eVal);
		}
	}

	return samples;
}

static const int MSADPCMAdaptationTable[] = {
	230, 230, 230, 230, 307, 409, 512, 614,
	768, 614, 512, 409, 307, 230, 230, 230
};


int16 ADPCMInputStream::decodeMS(ADPCMChannelStatus *c, byte code) {
	int32 predictor;

	predictor = (((c->sample1) * (c->coeff1)) + ((c->sample2) * (c->coeff2))) / 256;
	predictor += (signed)((code & 0x08) ? (code - 0x10) : (code)) * c->delta;

	predictor = CLIP<int32>(predictor, -32768, 32767);

	c->sample2 = c->sample1;
	c->sample1 = predictor;
	c->delta = (MSADPCMAdaptationTable[(int)code] * c->delta) >> 8;

	if (c->delta < 16)
		c->delta = 16;

	return (int16)predictor;
}

// 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, 1411,
	 1552
};

// Decode Linear to ADPCM
int16 ADPCMInputStream::decodeOKI(byte code) {
	int16 diff, E, samp;

	E = (2 * (code & 0x7) + 1) * okiStepSize[_status.ima_ch[0].stepIndex] / 8;
	diff = (code & 0x08) ? -E : E;
	samp = _status.ima_ch[0].last + diff;
	// Clip the values to +/- 2^11 (supposed to be 12 bits)
	samp = CLIP<int16>(samp, -2048, 2047);

	_status.ima_ch[0].last = samp;
	_status.ima_ch[0].stepIndex += stepAdjust(code);
	_status.ima_ch[0].stepIndex = CLIP<int32>(_status.ima_ch[0].stepIndex, 0, ARRAYSIZE(okiStepSize) - 1);

	// * 16 effectively converts 12-bit input to 16-bit output
	return samp * 16;
}

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::decodeIMA(byte code, int channel) {
	int32 E = (2 * (code & 0x7) + 1) * imaStepTable[_status.ima_ch[channel].stepIndex] / 8;
	int32 diff = (code & 0x08) ? -E : E;
	int32 samp = CLIP<int32>(_status.ima_ch[channel].last + diff, -32768, 32767);

	_status.ima_ch[channel].last = samp;
	_status.ima_ch[channel].stepIndex += stepAdjust(code);
	_status.ima_ch[channel].stepIndex = CLIP<int32>(_status.ima_ch[channel].stepIndex, 0, ARRAYSIZE(imaStepTable) - 1);

	return samp;
}

int16 ADPCMInputStream::decodeTinsel(int16 code, double eVal) {
	double sample;

	sample = (double) code;
	sample *= eVal * _status.predictor;
	sample += (_status.d0 * _status.K0) + (_status.d1 * _status.K1);

	_status.d1 = _status.d0;
	_status.d0 = sample;

	return (int16) CLIP<double>(sample, -32768.0, 32767.0);
}

RewindableAudioStream *makeADPCMStream(Common::SeekableReadStream *stream, bool disposeAfterUse, uint32 size, typesADPCM type, int rate, int channels, uint32 blockAlign) {
	return new ADPCMInputStream(stream, disposeAfterUse, size, type, rate, channels, blockAlign);
}

} // End of namespace Audio