diff options
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/adpcm.cpp | 46 |
1 files changed, 36 insertions, 10 deletions
diff --git a/sound/adpcm.cpp b/sound/adpcm.cpp index 70a1243956..83fcb82847 100644 --- a/sound/adpcm.cpp +++ b/sound/adpcm.cpp @@ -34,8 +34,6 @@ template <typesADPCM TYPE> class ADPCMInputStream : public AudioStream { private: - bool _evenPos; - byte _lastByte; Common::SeekableReadStream *_stream; uint32 _endpos; @@ -58,10 +56,14 @@ public: int getRate() const { return 22050; } }; +template <> +int16 ADPCMInputStream<kADPCMOki>::decode(byte code); +template <> +int16 ADPCMInputStream<kADPCMIma>::decode(byte code); template <typesADPCM TYPE> ADPCMInputStream<TYPE>::ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size) - : _stream(stream), _evenPos(true) { + : _stream(stream) { _status.last = 0; _status.stepIndex = 0; @@ -71,20 +73,44 @@ ADPCMInputStream<TYPE>::ADPCMInputStream(Common::SeekableReadStream *stream, uin template <typesADPCM TYPE> int ADPCMInputStream<TYPE>::readBuffer(int16 *buffer, const int numSamples) { int samples; + byte data; + + assert(numSamples % 2 == 0); // Since we process high and low nibbles separately never check buffer end // on low nibble - for (samples = 0; !_evenPos || samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples++) { - if (_evenPos) { - _lastByte = _stream->readByte(); - buffer[samples] = decode((_lastByte >> 4) & 0x0f); - } else { - buffer[samples] = decode(_lastByte & 0x0f); + for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples += 2) { + data = _stream->readByte(); + buffer[samples] = decode((data >> 4) & 0x0f); + buffer[samples + 1] = decode(data & 0x0f); + } + return samples; +} + +// Microsoft as usual tries to implement it differently. Though we don't +// use this now +#if 0 +template <> +int ADPCMInputStream<kADPCMIma>::readBuffer(int16 *buffer, const int numSamples) { + int samples; + uint32 data; + int nibble; + + for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos;) { + for (int channel = 0; channel < 2; channel++) { + data = _stream->readUint32LE(); + + for (nibble = 0; nibble < 8; nibble++) { + byte k = ((data & 0xf0000000) >> 28); + buffer[samples + channel + nibble * 2] = decode(k); + data <<= 4; + } } - _evenPos = !_evenPos; + samples += 16; } return samples; } +#endif // adjust the step for use on the next sample. template <typesADPCM TYPE> |