mirror of
https://github.com/libretro/scummvm.git
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249 lines
7.1 KiB
C++
249 lines
7.1 KiB
C++
/* ScummVM - Scumm Interpreter
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* Copyright (C) 2005-2006 The ScummVM project
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#include "common/stdafx.h"
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#include "common/endian.h"
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#include "sound/adpcm.h"
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#include "sound/audiostream.h"
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// TODO: Switch from a SeekableReadStream to a plain ReadStream. This requires
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// some internal refactoring but is definitely possible and will increase the
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// flexibility of this code.
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class ADPCMInputStream : public AudioStream {
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private:
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Common::SeekableReadStream *_stream;
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uint32 _endpos;
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int _channels;
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typesADPCM _type;
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uint32 _blockAlign;
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struct adpcmStatus {
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int32 last;
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int32 stepIndex;
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} _status;
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int16 stepAdjust(byte);
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int16 decodeOKI(byte);
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int16 decodeMSIMA(byte);
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public:
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ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size, typesADPCM type, int channels = 2, uint32 blockAlign = 0);
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~ADPCMInputStream() {};
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int readBuffer(int16 *buffer, const int numSamples);
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int readBufferOKI(int16 *buffer, const int numSamples);
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int readBufferMSIMA1(int16 *buffer, const int numSamples);
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int readBufferMSIMA2(int16 *buffer, const int numSamples);
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bool endOfData() const { return (_stream->eos() || _stream->pos() >= _endpos); }
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bool isStereo() const { return false; }
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int getRate() const { return 22050; }
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};
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// Routines to convert 12 bit linear samples to the
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// Dialogic or Oki ADPCM coding format aka VOX.
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// See also <http://www.comptek.ru/telephony/tnotes/tt1-13.html>
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//
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// In addition, also IMA ADPCM is supported. See
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// <http://www.multimedia.cx/simpleaudio.html>.
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ADPCMInputStream::ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size, typesADPCM type, int channels, uint32 blockAlign)
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: _stream(stream), _channels(channels), _type(type), _blockAlign(blockAlign) {
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_status.last = 0;
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_status.stepIndex = 0;
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_endpos = stream->pos() + size;
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if (type == kADPCMIma && blockAlign == 0)
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error("ADPCMInputStream(): blockAlign isn't specifiled for MS ADPCM IMA");
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}
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int ADPCMInputStream::readBuffer(int16 *buffer, const int numSamples) {
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switch (_type) {
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case kADPCMOki:
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return readBufferOKI(buffer, numSamples);
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break;
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case kADPCMIma:
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if (_channels == 1)
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return readBufferMSIMA1(buffer, numSamples);
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else
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return readBufferMSIMA2(buffer, numSamples);
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break;
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default:
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error("Unsupported ADPCM encoding");
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break;
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}
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return 0;
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}
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int ADPCMInputStream::readBufferOKI(int16 *buffer, const int numSamples) {
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int samples;
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byte data;
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assert(numSamples % 2 == 0);
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for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples += 2) {
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data = _stream->readByte();
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buffer[samples] = TO_LE_16(decodeOKI((data >> 4) & 0x0f));
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buffer[samples + 1] = TO_LE_16(decodeOKI(data & 0x0f));
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}
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return samples;
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}
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int ADPCMInputStream::readBufferMSIMA1(int16 *buffer, const int numSamples) {
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int samples;
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byte data;
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int blockLen;
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int i;
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assert(numSamples % 2 == 0);
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samples = 0;
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while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
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// read block header
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_status.last = _stream->readSint16LE();
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_status.stepIndex = _stream->readSint16LE();
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blockLen = MIN(_endpos - _stream->pos(), _blockAlign - 4);
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for (i = 0; i < blockLen && !_stream->eos() && _stream->pos() < _endpos; i++, samples += 2) {
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data = _stream->readByte();
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buffer[samples] = TO_LE_16(decodeMSIMA(data & 0x0f));
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buffer[samples + 1] = TO_LE_16(decodeMSIMA((data >> 4) & 0x0f));
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}
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}
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return samples;
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}
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// Microsoft as usual tries to implement it differently. This method
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// is used for stereo data.
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int ADPCMInputStream::readBufferMSIMA2(int16 *buffer, const int numSamples) {
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int samples;
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uint32 data;
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int nibble;
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for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos;) {
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for (int channel = 0; channel < 2; channel++) {
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data = _stream->readUint32LE();
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for (nibble = 0; nibble < 8; nibble++) {
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byte k = ((data & 0xf0000000) >> 28);
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buffer[samples + channel + nibble * 2] = TO_LE_16(decodeMSIMA(k));
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data <<= 4;
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}
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}
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samples += 16;
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}
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return samples;
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}
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// adjust the step for use on the next sample.
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int16 ADPCMInputStream::stepAdjust(byte code) {
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static const int16 adjusts[] = {-1, -1, -1, -1, 2, 4, 6, 8};
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return adjusts[code & 0x07];
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}
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static const int16 okiStepSize[49] = {
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16, 17, 19, 21, 23, 25, 28, 31,
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34, 37, 41, 45, 50, 55, 60, 66,
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73, 80, 88, 97, 107, 118, 130, 143,
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157, 173, 190, 209, 230, 253, 279, 307,
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337, 371, 408, 449, 494, 544, 598, 658,
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724, 796, 876, 963, 1060, 1166, 1282, 1411,
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1552
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};
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// Decode Linear to ADPCM
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int16 ADPCMInputStream::decodeOKI(byte code) {
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int16 diff, E, samp;
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E = (2 * (code & 0x7) + 1) * okiStepSize[_status.stepIndex] / 8;
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diff = (code & 0x08) ? -E : E;
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samp = _status.last + diff;
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// Clip the values to +/- 2^11 (supposed to be 12 bits)
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if (samp > 2048)
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samp = 2048;
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if (samp < -2048)
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samp = -2048;
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_status.last = samp;
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_status.stepIndex += stepAdjust(code);
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if (_status.stepIndex < 0)
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_status.stepIndex = 0;
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if (_status.stepIndex > ARRAYSIZE(okiStepSize) - 1)
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_status.stepIndex = ARRAYSIZE(okiStepSize) - 1;
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// * 16 effectively converts 12-bit input to 16-bit output
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return samp * 16;
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}
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static const uint16 imaStepTable[89] = {
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7, 8, 9, 10, 11, 12, 13, 14,
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16, 17, 19, 21, 23, 25, 28, 31,
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34, 37, 41, 45, 50, 55, 60, 66,
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73, 80, 88, 97, 107, 118, 130, 143,
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157, 173, 190, 209, 230, 253, 279, 307,
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337, 371, 408, 449, 494, 544, 598, 658,
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724, 796, 876, 963, 1060, 1166, 1282, 1411,
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1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
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3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
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7132, 7845, 8630, 9493,10442,11487,12635,13899,
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15289,16818,18500,20350,22385,24623,27086,29794,
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32767
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};
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int16 ADPCMInputStream::decodeMSIMA(byte code) {
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int32 diff, E, samp;
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E = (2 * (code & 0x7) + 1) * imaStepTable[_status.stepIndex] / 8;
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diff = (code & 0x08) ? -E : E;
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samp = _status.last + diff;
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if (samp < -0x8000)
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samp = -0x8000;
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else if (samp > 0x7fff)
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samp = 0x7fff;
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_status.last = samp;
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_status.stepIndex += stepAdjust(code);
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if (_status.stepIndex < 0)
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_status.stepIndex = 0;
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if (_status.stepIndex > ARRAYSIZE(imaStepTable) - 1)
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_status.stepIndex = ARRAYSIZE(imaStepTable) - 1;
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return samp;
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}
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AudioStream *makeADPCMStream(Common::SeekableReadStream *stream, uint32 size, typesADPCM type, int channels, uint32 blockAlign) {
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return new ADPCMInputStream(stream, size, type, channels, blockAlign);
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}
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