Initial commit

engines/tinsel/adpcm.cpp

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+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/stream.h"
+#include "common/util.h"
+
+#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 = (uint64)1 << start;
+	} else {
+		// Lower 6 bit are positive
+
+		// Truncate
+		start &= 0x1F;
+
+		_status.predictor = ((double) 1.0) / ((uint64)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;
+			default:
+				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