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LASTEXPRESS: Fix Engine Specific ADPCM to work using odd sized buffers

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This commit is contained in:
D G Turner 2022-03-31 02:09:57 +01:00
parent 284c3936ed
commit e53e1e70d4
1 changed files with 28 additions and 19 deletions
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47
engines/lastexpress/data/snd.cpp
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@ -350,6 +350,7 @@ class LastExpress_ADPCMStream : public Audio::ADPCMStream {
public:
LastExpress_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, uint32 blockSize, uint32 volume, bool looped) :
Audio::ADPCMStream(stream, disposeAfterUse, size, 44100, 1, blockSize) {
_decodedSampleCount = 0;
_currentVolume = 0;
_nextVolume = volume;
_smoothChangeTarget = volume;
@ -369,12 +370,6 @@ public:
int readBuffer(int16 *buffer, const int numSamples) override {
int samples = 0;
// Temporary data
int step = 0;
int sample = 0;
byte idx = 0;
assert(numSamples % 2 == 0);
while (_running && samples < numSamples) {
if (Audio::ADPCMStream::endOfData()) {
@ -403,21 +398,32 @@ public:
_currentVolume = _nextVolume;
}
for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples += 2) {
byte data = _stream->readByte();
_blockPos[0]++;
for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples++) {
if (_decodedSampleCount == 0) {
int step, sample;
byte idx;
// First nibble
idx = data >> 4;
step = stepTable[idx + _status.ima_ch[0].stepIndex / 4];
sample = CLIP<int>(imaTable[idx + _status.ima_ch[0].stepIndex / 4] + _status.ima_ch[0].last, -32767, 32767);
buffer[samples] = (sample * _currentVolume) >> 4;
byte data = _stream->readByte();
_blockPos[0]++;
// 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] = (_status.ima_ch[0].last * _currentVolume) >> 4;
// First nibble
idx = data >> 4;
step = stepTable[idx + _status.ima_ch[0].stepIndex / 4];
sample = CLIP<int>(imaTable[idx + _status.ima_ch[0].stepIndex / 4] + _status.ima_ch[0].last, -32767, 32767);
_decodedSamples[0] = (sample * _currentVolume) >> 4;
// 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);
_decodedSamples[1] = (_status.ima_ch[0].last * _currentVolume) >> 4;
_decodedSampleCount = 2;
}
// (1 - (count - 1)) ensures that _decodedSamples acts as a FIFO of depth 2
buffer[samples] = _decodedSamples[1 - (_decodedSampleCount - 1)];
_decodedSampleCount--;
}
}
@ -428,6 +434,9 @@ public:
void setVolumeSmoothly(uint32 newVolume) { _smoothChangeTarget = newVolume; }
private:
uint8 _decodedSampleCount;
int16 _decodedSamples[2];
uint32 _currentVolume;
uint32 _nextVolume;
uint32 _smoothChangeTarget;