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pcspk.cpp

/* ScummVM - Graphic Adventure Engine
*
* 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.
*
* $URL$
* $Id$
*
*/

#include "audio/softsynth/pcspk.h"
#include "audio/null.h"

namespace Audio {

const PCSpeaker::generatorFunc PCSpeaker::generateWave[] =
      {&PCSpeaker::generateSquare, &PCSpeaker::generateSine,
       &PCSpeaker::generateSaw,    &PCSpeaker::generateTriangle};

PCSpeaker::PCSpeaker(int rate) {
      _rate = rate;
      _wave = kWaveFormSquare;
      _playForever = false;
      _oscLength = 0;
      _oscSamples = 0;
      _remainingSamples = 0;
      _mixedSamples = 0;
      _volume = 255;
}

PCSpeaker::~PCSpeaker() {
}

00049 void PCSpeaker::play(WaveForm wave, int freq, int32 length) {
      Common::StackLock lock(_mutex);

      assert((wave >= kWaveFormSquare) && (wave <= kWaveFormTriangle));

      _wave = wave;
      _oscLength = _rate / freq;
      _oscSamples = 0;
      if (length == -1) {
            _remainingSamples = 1;
            _playForever = true;
      } else {
            _remainingSamples = (_rate * length) / 1000;
            _playForever = false;
      }
      _mixedSamples = 0;
}

00067 void PCSpeaker::stop(int32 delay) {
      Common::StackLock lock(_mutex);

      _remainingSamples = (_rate * delay) / 1000;
      _playForever = false;
}

00074 void PCSpeaker::setVolume(byte volume) {
      _volume = volume;
}

bool PCSpeaker::isPlaying() const {
      return _remainingSamples != 0;
}

00082 int PCSpeaker::readBuffer(int16 *buffer, const int numSamples) {
      Common::StackLock lock(_mutex);

      int i;

      for (i = 0; _remainingSamples && (i < numSamples); i++) {
            buffer[i] = generateWave[_wave](_oscSamples, _oscLength) * _volume;
            if (_oscSamples++ >= _oscLength)
                  _oscSamples = 0;
            if (!_playForever)
                  _remainingSamples--;
            _mixedSamples++;
      }

      // Clear the rest of the buffer
      if (i < numSamples)
            memset(buffer + i, 0, (numSamples - i) * sizeof(int16));

      return numSamples;
}

int8 PCSpeaker::generateSquare(uint32 x, uint32 oscLength) {
      return (x < (oscLength / 2)) ? 127 : -128;
}

int8 PCSpeaker::generateSine(uint32 x, uint32 oscLength) {
      if (oscLength == 0)
            return 0;

      // TODO: Maybe using a look-up-table would be better?
      return CLIP<int16>((int16) (128 * sin(2.0 * M_PI * x / oscLength)), -128, 127);
}

int8 PCSpeaker::generateSaw(uint32 x, uint32 oscLength) {
      if (oscLength == 0)
            return 0;

      return ((x * (65536 / oscLength)) >> 8) - 128;
}

int8 PCSpeaker::generateTriangle(uint32 x, uint32 oscLength) {
      if (oscLength == 0)
            return 0;

      int y = ((x * (65536 / (oscLength / 2))) >> 8) - 128;

      return (x <= (oscLength / 2)) ? y : (256 - y);
}

} // End of namespace Audio


//    Plugin interface
//    (This can only create a null driver since pc speaker support is not part of the
//    midi driver architecture. But we need the plugin for the options menu in the launcher
//    and for MidiDriver::detectDevice() which is more or less used by all engines.)

00139 class PCSpeakerMusicPlugin : public NullMusicPlugin {
public:
00141       const char *getName() const {
            return _s("PC Speaker Emulator");
      }

00145       const char *getId() const {
            return "pcspk";
      }

      MusicDevices getDevices() const;
};

00152 MusicDevices PCSpeakerMusicPlugin::getDevices() const {
      MusicDevices devices;
      devices.push_back(MusicDevice(this, "", MT_PCSPK));
      return devices;
}

00158 class PCjrMusicPlugin : public NullMusicPlugin {
public:
00160       const char *getName() const {
            return _s("IBM PCjr Emulator");
      }

00164       const char *getId() const {
            return "pcjr";
      }

      MusicDevices getDevices() const;
};

00171 MusicDevices PCjrMusicPlugin::getDevices() const {
      MusicDevices devices;
      devices.push_back(MusicDevice(this, "", MT_PCJR));
      return devices;
}

//#if PLUGIN_ENABLED_DYNAMIC(PCSPK)
      //REGISTER_PLUGIN_DYNAMIC(PCSPK, PLUGIN_TYPE_MUSIC, PCSpeakerMusicPlugin);
//#else
      REGISTER_PLUGIN_STATIC(PCSPK, PLUGIN_TYPE_MUSIC, PCSpeakerMusicPlugin);
//#endif

//#if PLUGIN_ENABLED_DYNAMIC(PCJR)
      //REGISTER_PLUGIN_DYNAMIC(PCJR, PLUGIN_TYPE_MUSIC, PCjrMusicPlugin);
//#else
      REGISTER_PLUGIN_STATIC(PCJR, PLUGIN_TYPE_MUSIC, PCjrMusicPlugin);
//#endif

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