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Diffstat (limited to 'sound/decoders/vag.cpp')
-rw-r--r-- | sound/decoders/vag.cpp | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/sound/decoders/vag.cpp b/sound/decoders/vag.cpp new file mode 100644 index 0000000000..f2c9281d80 --- /dev/null +++ b/sound/decoders/vag.cpp @@ -0,0 +1,123 @@ +/* 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 "sound/decoders/vag.h" + +namespace Audio { + +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; +} + +} |