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audiostream.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2001-2005 The ScummVM project
 *
 * 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.
 *
 * $Header: /cvsroot/scummvm/scummvm/sound/audiostream.cpp,v 1.77.2.1 2005/10/18 02:11:26 sev Exp $
 *
 */

#include "common/stdafx.h"
#include "common/file.h"
#include "common/util.h"
#include "sound/audiostream.h"
#include "sound/mixer.h"
#include "sound/mp3.h"
#include "sound/vorbis.h"
#include "sound/flac.h"

struct StreamFileFormat {
      /** Decodername */
      const char* decoderName;
      const char* fileExtension;
      /**
       * Pointer to a function which tries to open a file of type StreamFormat.
       * Return NULL in case of an error (invalid/nonexisting file).
       */
      AudioStream* (*openStreamFile)(Common::File *file, uint32 size);
};

static const StreamFileFormat STREAM_FILEFORMATS[] = {
      /* decoderName,         fileExt, openStreamFuntion */
#ifdef USE_FLAC
      { "Flac",               "flac", makeFlacStream },
      { "Flac",               "fla",  makeFlacStream },
#endif
#ifdef USE_VORBIS
      { "Ogg Vorbis",         "ogg",  makeVorbisStream },
#endif
#ifdef USE_MAD
      { "Mpeg Layer 3", "mp3",  makeMP3Stream },
#endif

      { NULL, NULL, NULL } // Terminator
};

00058 AudioStream* AudioStream::openStreamFile(const char *filename)
{
      char buffer[1024];
      const uint len = strlen(filename);
      assert(len+6 < sizeof(buffer)); // we need a bigger buffer if wrong

      memcpy(buffer, filename, len);
      buffer[len] = '.';
      char *ext = &buffer[len+1];

      AudioStream* stream = NULL;
      Common::File *fileHandle = new Common::File();

      for (int i = 0; i < ARRAYSIZE(STREAM_FILEFORMATS)-1 && stream == NULL; ++i) {
            strcpy(ext, STREAM_FILEFORMATS[i].fileExtension);
            fileHandle->open(buffer);
            if (fileHandle->isOpen())
                  stream = STREAM_FILEFORMATS[i].openStreamFile(fileHandle, fileHandle->size());
      }

      // Do not reference the file anymore. If the stream didn't incRef the file,
      // the object will be deleted (and the file be closed).
      fileHandle->decRef();

      if (stream == NULL) {
            debug(1, "AudioStream: Could not open compressed AudioFile %s", filename);
      }

      return stream;
}

#pragma mark -
#pragma mark --- LinearMemoryStream ---
#pragma mark -


/**
 * A simple raw audio stream, purely memory based. It operates on a single
 * block of data, which is passed to it upon creation.
 * Optionally supports looping the sound.
 *
 * Design note: This code tries to be as optimized as possible (without
 * resorting to assembly, that is). To this end, it is written as a template
 * class. This way the compiler can actually create optimized code for each
 * special code. This results in a total of 12 versions of the code being
 * generated.
 */
template<bool stereo, bool is16Bit, bool isUnsigned, bool isLE>
00106 class LinearMemoryStream : public AudioStream {
protected:
      const byte *_ptr;
      const byte *_end;
      const byte *_loopPtr;
      const byte *_loopEnd;
      const int _rate;
      const byte *_origPtr;

      inline bool eosIntern() const { return _ptr >= _end; };
public:
      LinearMemoryStream(int rate, const byte *ptr, uint len, uint loopOffset, uint loopLen, bool autoFreeMemory)
            : _ptr(ptr), _end(ptr+len), _loopPtr(0), _loopEnd(0), _rate(rate) {

            // Verify the buffer sizes are sane
            if (is16Bit && stereo)
                  assert((len & 3) == 0 && (loopLen & 3) == 0);
            else if (is16Bit || stereo)
                  assert((len & 1) == 0 && (loopLen & 1) == 0);

            if (loopLen) {
                  _loopPtr = _ptr + loopOffset;
                  _loopEnd = _loopPtr + loopLen;
            }
            if (stereo) // Stereo requires even sized data
                  assert(len % 2 == 0);

            _origPtr = autoFreeMemory ? ptr : 0;
      }
      ~LinearMemoryStream() {
            free(const_cast<byte *>(_origPtr));
      }
      int readBuffer(int16 *buffer, const int numSamples);

00140       bool isStereo() const         { return stereo; }
00141       bool endOfData() const        { return eosIntern(); }

00143       int getRate() const                 { return _rate; }
};

template<bool stereo, bool is16Bit, bool isUnsigned, bool isLE>
00147 int LinearMemoryStream<stereo, is16Bit, isUnsigned, isLE>::readBuffer(int16 *buffer, const int numSamples) {
      int samples = 0;
      while (samples < numSamples && !eosIntern()) {
            const int len = MIN(numSamples, samples + (int)(_end - _ptr) / (is16Bit ? 2 : 1));
            while (samples < len) {
                  *buffer++ = READ_ENDIAN_SAMPLE(is16Bit, isUnsigned, _ptr, isLE);
                  _ptr += (is16Bit ? 2 : 1);
                  samples++;
            }
            // Loop, if looping was specified
            if (_loopPtr && eosIntern()) {
                  _ptr = _loopPtr;
                  _end = _loopEnd;
            }
      }
      return samples;
}


#pragma mark -
#pragma mark --- Input stream factory ---
#pragma mark -

/* 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_LINEAR(STEREO, UNSIGNED) \
            if (is16Bit) { \
                  if (isLE) \
                        return new LinearMemoryStream<STEREO, true, UNSIGNED, true>(rate, ptr, len, loopOffset, loopLen, autoFree); \
                  else  \
                        return new LinearMemoryStream<STEREO, true, UNSIGNED, false>(rate, ptr, len, loopOffset, loopLen, autoFree); \
            } else \
                  return new LinearMemoryStream<STEREO, false, UNSIGNED, false>(rate, ptr, len, loopOffset, loopLen, autoFree)

AudioStream *makeLinearInputStream(int rate, byte flags, const byte *ptr, uint32 len, uint loopOffset, uint loopLen) {
      const bool isStereo   = (flags & Audio::Mixer::FLAG_STEREO) != 0;
      const bool is16Bit    = (flags & Audio::Mixer::FLAG_16BITS) != 0;
      const bool isUnsigned = (flags & Audio::Mixer::FLAG_UNSIGNED) != 0;
      const bool isLE       = (flags & Audio::Mixer::FLAG_LITTLE_ENDIAN) != 0;
      const bool autoFree   = (flags & Audio::Mixer::FLAG_AUTOFREE) != 0;

      if (isStereo) {
            if (isUnsigned) {
                  MAKE_LINEAR(true, true);
            } else {
                  MAKE_LINEAR(true, false);
            }
      } else {
            if (isUnsigned) {
                  MAKE_LINEAR(false, true);
            } else {
                  MAKE_LINEAR(false, false);
            }
      }
}

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