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adlibmusic.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2003-2004 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * $Header: /cvsroot/scummvm/scummvm/sky/music/adlibmusic.cpp,v 1.22 2004/11/27 16:18:25 fingolfin Exp $
 *
 */

#include "sky/music/adlibmusic.h"
#include "sky/music/adlibchannel.h"
#include "sound/mixer.h"
#include "sky/sky.h"

namespace Sky {

AdlibMusic::AdlibMusic(SoundMixer *pMixer, Disk *pDisk, OSystem *system)
      : MusicBase(pDisk, system) {
      
      _driverFileBase = 60202;
      _mixer = pMixer;
      _sampleRate = pMixer->getOutputRate();
      
      _opl = makeAdlibOPL(_sampleRate);

      _mixer->setupPremix(this);
}

AdlibMusic::~AdlibMusic(void) {

      _mixer->setupPremix(0);
//    YM3812Shutdown();
}

void AdlibMusic::setVolume(uint8 volume) {

      _musicVolume = volume;
      for (uint8 cnt = 0; cnt < _numberOfChannels; cnt++)
            _channels[cnt]->updateVolume(volume | 128);
}

void AdlibMusic::premixerCall(int16 *data, uint len) {

      if (_musicData == NULL) {
            // no music loaded
            memset(data, 0, 2 * len * sizeof(int16));
      } else if ((_currentMusic == 0) || (_numberOfChannels == 0)) {
            // music loaded but not played as of yet
            memset(data, 0, 2 * len * sizeof(int16));
            // poll anyways as pollMusic() can activate the music
            pollMusic();
            _nextMusicPoll = _sampleRate/50;
      } else {
            uint32 render;
            int16 *origData = data;
            uint origLen = len;
            while (len) {
                  render = (len > _nextMusicPoll) ? (_nextMusicPoll) : (len);
                  len -= render;
                  _nextMusicPoll -= render;
                  YM3812UpdateOne(_opl, data, render);
                  data += render;
                  if (_nextMusicPoll == 0) {
                        pollMusic();
                        _nextMusicPoll = _sampleRate/50;
                  }
            }

            // Convert mono data to stereo
            for (int i = (origLen - 1); i >= 0; i--) {
                  origData[2 * i] = origData[2 * i + 1] = origData[i];
            }
      }
}

void AdlibMusic::setupPointers(void) {

      if (SkyEngine::_systemVars.gameVersion == 109) {
            // disk demo uses a different adlib driver version, some offsets have changed
            //_musicDataLoc = (_musicData[0x11CC] << 8) | _musicData[0x11CB];
            //_initSequence = _musicData + 0xEC8;
            
            _musicDataLoc = READ_LE_UINT16(_musicData + 0x1200);
            _initSequence = _musicData + 0xEFB;
      } else if (SkyEngine::_systemVars.gameVersion == 267) {
            _musicDataLoc = READ_LE_UINT16(_musicData + 0x11F7);
            _initSequence = _musicData + 0xE87;
      } else {
            _musicDataLoc = READ_LE_UINT16(_musicData + 0x1201);
            _initSequence = _musicData + 0xE91;
      }
      _nextMusicPoll = 0;
}

void AdlibMusic::setupChannels(uint8 *channelData) {

      _numberOfChannels = channelData[0];
      channelData++;
      for (uint8 cnt = 0; cnt < _numberOfChannels; cnt++) {
            uint16 chDataStart = ((channelData[(cnt << 1) | 1] << 8) | channelData[cnt << 1]) + _musicDataLoc;
            _channels[cnt] = new AdlibChannel(_opl, _musicData, chDataStart);
            _channels[cnt]->updateVolume(_musicVolume | 128);
      }
}

void AdlibMusic::startDriver(void) {

      uint16 cnt = 0;
      while (_initSequence[cnt] || _initSequence[cnt+1]) {
            OPLWriteReg (_opl, _initSequence[cnt], _initSequence[cnt+1]);
            cnt += 2;
      }
      _allowedCommands = 0xD;
}

} // End of namespace Sky

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