pcm.cpp

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/* xoreos - A reimplementation of BioWare's Aurora engine
 *
 * xoreos is the legal property of its developers, whose names
 * can be found in the AUTHORS file distributed with this source
 * distribution.
 *
 * xoreos 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 3
 * of the License, or (at your option) any later version.
 *
 * xoreos 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 xoreos. If not, see <http://www.gnu.org/licenses/>.
 */

/* Based on ScummVM (<http://scummvm.org>) code, which is released
 * under the terms of version 2 or later of the GNU General Public
 * License.
 *
 * The original copyright note in ScummVM reads as follows:
 *
 * 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.
 */

#include "src/common/disposableptr.h"
#include "src/common/readstream.h"

#include "src/sound/audiostream.h"
#include "src/sound/decoders/pcm.h"

namespace Sound {

// This used to be an inline template function, but
// buggy template function handling in MSVC6 forced
// us to go with the macro approach. So far this is
// the only template function that MSVC6 seemed to
// compile incorrectly. Knock on wood.
#define READ_ENDIAN_SAMPLE(is16Bit, isUnsigned, ptr, isLE) \
    ((is16Bit ? (isLE ? _stream->readUint16LE() : _stream->readUint16BE()) : (_stream->readByte() << 8)) ^ (isUnsigned ? 0x8000 : 0))


template<bool is16Bit, bool isUnsigned, bool isLE>
class PCMStream : public RewindableAudioStream {

protected:
    const int _rate;                     
    const int _channels;                 

    uint64 _length;

    Common::DisposablePtr<Common::SeekableReadStream> _stream; 

public:
    PCMStream(int rate, int channels, bool disposeStream, Common::SeekableReadStream *stream)
        : _rate(rate), _channels(channels), _stream(stream, disposeStream) {

        _length = stream->size() / _channels / (is16Bit ? 2 : 1);
    }

    virtual ~PCMStream() {
    }

    size_t readBuffer(int16 *buffer, const size_t numSamples);

    int getChannels() const { return _channels; }
    bool endOfData() const { return _stream->pos() >= _stream->size(); }
    int getRate() const { return _rate; }
    uint64 getLength() const { return _length; }

    bool rewind();
};

template<bool is16Bit, bool isUnsigned, bool isLE>
size_t PCMStream<is16Bit, isUnsigned, isLE>::readBuffer(int16 *buffer, const size_t numSamples) {
    size_t samples = numSamples;

    while (samples > 0 && !endOfData()) {
        *buffer++ = READ_ENDIAN_SAMPLE(is16Bit, isUnsigned, _ptr, isLE);
        samples--;
    }

    return numSamples - samples;
}

template<bool is16Bit, bool isUnsigned, bool isLE>
bool PCMStream<is16Bit, isUnsigned, isLE>::rewind() {
    // Easy peasy, lemon squeezee
    _stream->seek(0);
    return true;
}

/* In the following, we use preprocessor / macro tricks to simplify the code
 * which instantiates the input streams. We used to use template functions for
 * this, but MSVC6 / EVC 3-4 (used for WinCE builds) are extremely buggy when it
 * comes to this feature of C++... so as a compromise we use macros to cut down
 * on the (source) code duplication a bit.
 * So while normally macro tricks are said to make maintenance harder, in this
 * particular case it should actually help it :-)
 */

#define MAKE_RAW_STREAM(UNSIGNED) \
    if (is16Bit) { \
        if (isLE) \
            return new PCMStream<true, UNSIGNED, true>(rate, channels, disposeAfterUse, stream); \
        else  \
            return new PCMStream<true, UNSIGNED, false>(rate, channels, disposeAfterUse, stream); \
    } else \
        return new PCMStream<false, UNSIGNED, false>(rate, channels, disposeAfterUse, stream)


RewindableAudioStream *makePCMStream(Common::SeekableReadStream *stream,
                                   int rate, byte flags, int channels,
                                   bool disposeAfterUse) {

    const bool is16Bit    = (flags & FLAG_16BITS) != 0;
    const bool isUnsigned = (flags & FLAG_UNSIGNED) != 0;
    const bool isLE       = (flags & FLAG_LITTLE_ENDIAN) != 0;

    if (isUnsigned) {
        MAKE_RAW_STREAM(true);
    } else {
        MAKE_RAW_STREAM(false);
    }
}

class PacketizedPCMStream : public StatelessPacketizedAudioStream {
public:
    PacketizedPCMStream(int rate, byte flags, int channels) :
        StatelessPacketizedAudioStream(rate, channels), _flags(flags) {}

protected:
    AudioStream *makeStream(Common::SeekableReadStream *data);

private:
    byte _flags;
};

AudioStream *PacketizedPCMStream::makeStream(Common::SeekableReadStream *data) {
    return makePCMStream(data, getRate(), _flags, getChannels());
}

PacketizedAudioStream *makePacketizedPCMStream(int rate, byte flags, int channels) {
    return new PacketizedPCMStream(rate, flags, channels);
}

} // End of namespace Sound