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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 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
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