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Simplified common buffer reader. Implemented now unused Microsoft IMA
ADPCM buffer reader. These folks invented ye another incompatible standard and here it will sit #if 0'ed just for a case. svn-id: r19164
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@ -34,8 +34,6 @@
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template <typesADPCM TYPE>
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class ADPCMInputStream : public AudioStream {
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private:
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bool _evenPos;
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byte _lastByte;
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Common::SeekableReadStream *_stream;
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uint32 _endpos;
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@ -58,10 +56,14 @@ public:
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int getRate() const { return 22050; }
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};
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template <>
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int16 ADPCMInputStream<kADPCMOki>::decode(byte code);
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template <>
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int16 ADPCMInputStream<kADPCMIma>::decode(byte code);
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template <typesADPCM TYPE>
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ADPCMInputStream<TYPE>::ADPCMInputStream(Common::SeekableReadStream *stream, uint32 size)
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: _stream(stream), _evenPos(true) {
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: _stream(stream) {
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_status.last = 0;
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_status.stepIndex = 0;
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@ -71,21 +73,45 @@ ADPCMInputStream<TYPE>::ADPCMInputStream(Common::SeekableReadStream *stream, uin
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template <typesADPCM TYPE>
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int ADPCMInputStream<TYPE>::readBuffer(int16 *buffer, const int numSamples) {
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int samples;
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byte data;
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assert(numSamples % 2 == 0);
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// Since we process high and low nibbles separately never check buffer end
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// on low nibble
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for (samples = 0; !_evenPos || samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples++) {
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if (_evenPos) {
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_lastByte = _stream->readByte();
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buffer[samples] = decode((_lastByte >> 4) & 0x0f);
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} else {
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buffer[samples] = decode(_lastByte & 0x0f);
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}
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_evenPos = !_evenPos;
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for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos; samples += 2) {
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data = _stream->readByte();
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buffer[samples] = decode((data >> 4) & 0x0f);
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buffer[samples + 1] = decode(data & 0x0f);
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}
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return samples;
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}
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// Microsoft as usual tries to implement it differently. Though we don't
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// use this now
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#if 0
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template <>
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int ADPCMInputStream<kADPCMIma>::readBuffer(int16 *buffer, const int numSamples) {
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int samples;
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uint32 data;
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int nibble;
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for (samples = 0; samples < numSamples && !_stream->eos() && _stream->pos() < _endpos;) {
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for (int channel = 0; channel < 2; channel++) {
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data = _stream->readUint32LE();
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for (nibble = 0; nibble < 8; nibble++) {
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byte k = ((data & 0xf0000000) >> 28);
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buffer[samples + channel + nibble * 2] = decode(k);
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data <<= 4;
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}
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}
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samples += 16;
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}
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return samples;
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}
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#endif
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// adjust the step for use on the next sample.
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template <typesADPCM TYPE>
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int16 ADPCMInputStream<TYPE>::stepAdjust(byte code) {
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