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paula.h

/* 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: https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/tags/release-0-11-1/sound/mods/paula.h $
 * $Id: paula.h 30944 2008-02-23 22:50:18Z sev $
 *
 */

#ifndef SOUND_MODS_PAULA_H
#define SOUND_MODS_PAULA_H

#include "sound/audiostream.h"
#include "common/frac.h"
#include "common/mutex.h"

namespace Audio {

/**
 * Emulation of the "Paula" Amiga music chip
 * The interrupt frequency specifies the number of mixed wavesamples between
 * calls of the interrupt method
 */
00040 class Paula : public AudioStream {
public:
      static const int NUM_VOICES = 4;

      Paula(bool stereo = false, int rate = 44100, int interruptFreq = 0);
      ~Paula();

      bool playing() const { return _playing; }
      void setInterruptFreq(int freq) { _curInt = _intFreq = freq; }
      void clearVoice(byte voice);
      void clearVoices() { for (int i = 0; i < NUM_VOICES; ++i) clearVoice(i); }
      void startPlay(void) { _playing = true; }
      void stopPlay(void) { _playing = false; }
      void pausePlay(bool pause) { _playing = !pause; }

// AudioStream API
      int readBuffer(int16 *buffer, const int numSamples);
00057       bool isStereo() const { return _stereo; }
00058       bool endOfData() const { return _end; }
00059       int getRate() const { return _rate; }

protected:
      struct Channel {
            const int8 *data;
            const int8 *dataRepeat;
            uint32 length;
            uint32 lengthRepeat;
            int16 period;
            byte volume;
            frac_t offset;
            byte panning; // For stereo mixing: 0 = far left, 255 = far right
      };

      bool _end;
      Common::Mutex _mutex;

      virtual void interrupt(void) = 0;

      void startPaula() {
            _playing = true;
            _end = false;
      }
      
      void stopPaula() {
            _playing = false;
            _end = true;
      }
      
      void setChannelPanning(byte channel, byte panning) {
            assert(channel < NUM_VOICES);
            _voice[channel].panning = panning;
      }

      void setChannelPeriod(byte channel, int16 period) {
            assert(channel < NUM_VOICES);
            _voice[channel].period = period;
      }

      void setChannelVolume(byte channel, byte volume) {
            assert(channel < NUM_VOICES);
            _voice[channel].volume = volume;
      }

      void setChannelData(uint8 channel, const int8 *data, const int8 *dataRepeat, uint32 length, uint32 lengthRepeat, int32 offset = 0) {
            assert(channel < NUM_VOICES);

            // For now, we only support 32k samples, as we use 16bit fixed point arithmetics.
            // If this ever turns out to be a problem, we can still enhance this code.
            assert(0 <= offset && offset < 32768);
            assert(length < 32768);
            assert(lengthRepeat < 32768);

            Channel &ch = _voice[channel];
            ch.data = data;
            ch.dataRepeat = dataRepeat;
            ch.length = length;
            ch.lengthRepeat = lengthRepeat;
            ch.offset = intToFrac(offset);
      }

      void setChannelOffset(byte channel, frac_t offset) {
            assert(channel < NUM_VOICES);
            assert(0 <= offset);
            _voice[channel].offset = offset;
      }

      frac_t getChannelOffset(byte channel) {
            assert(channel < NUM_VOICES);
            return _voice[channel].offset;
      }

private:
      Channel _voice[NUM_VOICES];

      const bool _stereo;
      const int _rate;
      int _intFreq;
      int _curInt;
      bool _playing;

      template<bool stereo>
      int readBufferIntern(int16 *buffer, const int numSamples);
};

} // End of namespace Audio

#endif

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