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Diffstat (limited to 'engines/tinsel/adpcm.cpp')
| -rw-r--r-- | engines/tinsel/adpcm.cpp | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/engines/tinsel/adpcm.cpp b/engines/tinsel/adpcm.cpp new file mode 100644 index 0000000000..ec51d150dc --- /dev/null +++ b/engines/tinsel/adpcm.cpp @@ -0,0 +1,168 @@ +/* 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 "tinsel/adpcm.h" + +namespace Tinsel { + +static const double TinselFilterTable[4][2] = { + {0, 0 }, + {0.9375, 0}, + {1.796875, -0.8125}, + {1.53125, -0.859375} +}; + +void Tinsel_ADPCMStream::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]; +} + +int16 Tinsel_ADPCMStream::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); +} + +int Tinsel4_ADPCMStream::readBuffer(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 Tinsel6_ADPCMStream::readBuffer(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 Tinsel8_ADPCMStream::readBuffer(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; +} + + +} // End of namespace Tinsel |