diff options
| -rw-r--r-- | engines/lastexpress/data/snd.cpp | 75 |
1 files changed, 35 insertions, 40 deletions
diff --git a/engines/lastexpress/data/snd.cpp b/engines/lastexpress/data/snd.cpp index 29a81bec75..9e92ded204 100644 --- a/engines/lastexpress/data/snd.cpp +++ b/engines/lastexpress/data/snd.cpp @@ -38,7 +38,7 @@ namespace LastExpress { #pragma region Sound filters tables -static const int filterData[1424] = { +static const int stepTable[1424] = { 0, 0, 0, 0, 128, 256, 384, 512, 0, 0, 0, 0, 128, 256, 384, 512, 0, 0, 0, 0, 192, 320, 448, 576, 0, 0, 0, 0, 192, 320, 448, 576, 64, 64, 64, 64, 256, 384, 512, 640, @@ -195,7 +195,7 @@ static const int filterData[1424] = { 5632 }; -static const int filterData2[1424] = { +static const int imaTable[1424] = { 0, 2, 4, 6, 7, 9, 11, 13, 0, -2, -4, -6, -7, -9, -11, -13, 1, 3, 5, 7, 9, 11, 13, 15, -1, -3, -5, -7, -9, -11, -13, -15, 1, 3, 5, 7, 10, 12, 14, 16, -1, -3, -5, @@ -362,6 +362,10 @@ public: int readBuffer(int16 *buffer, const int numSamples) { int samples = 0; + // Temporary data + int step = 0; + int sample = 0; + byte idx = 0; assert(numSamples % 2 == 0); @@ -369,15 +373,37 @@ public: if (_blockPos[0] == _blockAlign) { // read block header _status.ima_ch[0].last = _stream->readSint16LE(); - _status.ima_ch[0].stepIndex = _stream->readSint16LE(); + _status.ima_ch[0].stepIndex = _stream->readSint16LE() << 6; _blockPos[0] = 4; + + // Get current filter + _currentFilterId = _nextFilterId; + _nextFilterId = -1; + + // No filter: skip decoding + if (_currentFilterId == -1) + break; + + // Compute step adjustment + _stepAdjust1 = p1s[_currentFilterId]; + _stepAdjust2 = p2s[_currentFilterId]; } for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples += 2) { byte data = _stream->readByte(); _blockPos[0]++; - buffer[samples] = decodeIMA((data >> 4) & 0x0f); - buffer[samples + 1] = decodeIMA(data & 0x0f); + + // First nibble + idx = data >> 4; + step = stepTable[idx + _status.ima_ch[0].stepIndex / 4]; + sample = CLIP(imaTable[idx + _status.ima_ch[0].stepIndex / 4] + _status.ima_ch[0].last, -32767, 32767); + buffer[samples] = (_stepAdjust2 * sample) >> _stepAdjust1; + + // Second nibble + idx = data & 0xF; + _status.ima_ch[0].stepIndex = stepTable[idx + step / 4]; + _status.ima_ch[0].last = CLIP(imaTable[idx + step / 4] + sample, -32767, 32767); + buffer[samples + 1] = (_stepAdjust2 * _status.ima_ch[0].last) >> _stepAdjust1; } } @@ -387,41 +413,10 @@ public: void setFilterId(int32 filterId) { _nextFilterId = filterId; } private: - int32 _currentFilterId; - int32 _nextFilterId; // the sound filter id, -1 for none - - /** - * Sound filter - * - * @param [in] data If non-null, the input data - * @param [in,out] buffer If non-null, the output buffer. - * @param p1 The first filter input. - * @param p2 The second filter input. - */ - static void soundFilter(byte *data, int16 *buffer, int p1, int p2) { - int data1, data2, data1p, data2p; - byte idx; - - data2 = data[0]; - data1 = data[1] << 6; - - data += 2; - - for (int count = 0; count < 735; count++) { - idx = data[count] >> 4; - - data1p = filterData[idx + data1]; - data2p = CLIP(filterData2[idx + data1] + data2, -32767, 32767); - - buffer[2 * count] = (p2 * data2p) >> p1; - - idx = data[count] & 0xF; - - data1 = filterData[idx + data1p]; - data2 = CLIP(filterData2[idx + data1p] + data2p, -32767, 32767); - buffer[2 * count + 1] = (p2 * data2) >> p1; - } - } + int32 _currentFilterId; + int32 _nextFilterId; // the sound filter id, -1 for none + int32 _stepAdjust1; + int32 _stepAdjust2; }; ////////////////////////////////////////////////////////////////////////// |