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gmchannel.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: https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/tags/release-0-11-1/engines/sky/music/gmchannel.cpp $
 * $Id: gmchannel.cpp 30944 2008-02-23 22:50:18Z sev $
 *
 */

#include "gmchannel.h"
#include "common/util.h"
#include "sound/mididrv.h"

namespace Sky {

GmChannel::GmChannel(uint8 *pMusicData, uint16 startOfData, MidiDriver *pMidiDrv, const byte *pInstMap, const byte *veloTab) {

      _musicData = pMusicData;
      _midiDrv = pMidiDrv;
      _channelData.midiChannelNumber = 0;
      _channelData.loopPoint = startOfData;
      _channelData.eventDataPtr = startOfData;
      _channelData.channelActive = true;
      _channelData.nextEventTime = getNextEventTime();
      _instMap = pInstMap;
      _veloTab = veloTab;

      _musicVolume = 0x7F;
      _currentChannelVolume = 0x7F;
}

GmChannel::~GmChannel(void) {
      stopNote();
}

bool GmChannel::isActive(void) {
      return _channelData.channelActive;
}

void GmChannel::updateVolume(uint16 pVolume) {

      _musicVolume = pVolume;
      if (_musicVolume > 0)
            _musicVolume = (_musicVolume * 2) / 3 + 43;

      uint8 newVol = (_currentChannelVolume * _musicVolume) >> 7;
      _midiDrv->send((0xB0 | _channelData.midiChannelNumber) | 0x700 | (newVol << 16));
}

void GmChannel::stopNote(void) {

      // All Notes Off
      _midiDrv->send((0xB0 | _channelData.midiChannelNumber) | 0x7B00 | 0 | 0x79000000);
      // Reset the Pitch Wheel. See bug #1016556.
      _midiDrv->send((0xE0 | _channelData.midiChannelNumber) | 0x400000);
}

int32 GmChannel::getNextEventTime(void) {

      int32 retV = 0;
      uint8 cnt, lVal = 0;
      for (cnt = 0; cnt < 4; cnt++) {
            lVal = _musicData[_channelData.eventDataPtr];
            _channelData.eventDataPtr++;
            retV = (retV << 7) | (lVal & 0x7F);
            if (!(lVal & 0x80))
                  break;
      }
      if (lVal & 0x80) { // should never happen
            return -1;
      } else
            return retV;
}

uint8 GmChannel::process(uint16 aktTime) {

      if (!_channelData.channelActive)
            return 0;

      uint8 returnVal = 0;

      _channelData.nextEventTime -= aktTime;
      uint8 opcode;

      while ((_channelData.nextEventTime < 0) && (_channelData.channelActive)) {
            opcode = _musicData[_channelData.eventDataPtr];
            _channelData.eventDataPtr++;
            if (opcode&0x80) {
                  if (opcode == 0xFF) {
                        // dummy opcode
                  } else if (opcode >= 0x90) {
                        switch (opcode&0xF) {
                        case 0: com90_caseNoteOff(); break;
                        case 1: com90_stopChannel(); break;
                        case 2: com90_setupInstrument(); break;
                        case 3:
                              returnVal = com90_updateTempo();
                              break;
                        case 5: com90_getPitch(); break;
                        case 6: com90_getChannelVolume(); break;
                        case 8: com90_loopMusic(); break;
                        case 9: com90_keyOff(); break;
                        case 11: com90_getChannelPanValue(); break;
                        case 12: com90_setLoopPoint(); break;
                        case 13: com90_getChannelControl(); break;
                        
                        default:
                              error("GmChannel: Unknown music opcode 0x%02X", opcode);
                              break;
                        }
                  } else {
                        // new midi channel assignment
                        _channelData.midiChannelNumber = opcode&0xF;
                  }
            } else {
                  _channelData.note = opcode;
                  byte velocity = _musicData[_channelData.eventDataPtr];
                  if (_veloTab)
                        velocity = _veloTab[velocity];
                  _channelData.eventDataPtr++;
                  _midiDrv->send((0x90 | _channelData.midiChannelNumber) | (opcode << 8) | (velocity << 16));
            }
            if (_channelData.channelActive)
                  _channelData.nextEventTime += getNextEventTime();
      }
      return returnVal;
}

//- command 90h routines

void GmChannel::com90_caseNoteOff(void) {

      _midiDrv->send((0x90 | _channelData.midiChannelNumber) | (_musicData[_channelData.eventDataPtr] << 8));
      _channelData.eventDataPtr++;
}

void GmChannel::com90_stopChannel(void) {

      stopNote();
      _channelData.channelActive = false;
}

void GmChannel::com90_setupInstrument(void) {
      byte instrument = _musicData[_channelData.eventDataPtr];
      if (_instMap)
            instrument = _instMap[instrument];
      _midiDrv->send((0xC0 | _channelData.midiChannelNumber) | (instrument << 8));
      _channelData.eventDataPtr++;
}

uint8 GmChannel::com90_updateTempo(void) {
      return _musicData[_channelData.eventDataPtr++];
}

void GmChannel::com90_getPitch(void) {

      _midiDrv->send((0xE0 | _channelData.midiChannelNumber) | 0 | (_musicData[_channelData.eventDataPtr] << 16));
      _channelData.eventDataPtr++;
}

void GmChannel::com90_getChannelVolume(void) {

      _currentChannelVolume = _musicData[_channelData.eventDataPtr++];
      uint8 newVol = (uint8)((_currentChannelVolume * _musicVolume) >> 7);
      _midiDrv->send((0xB0 | _channelData.midiChannelNumber) | 0x700 | (newVol << 16));
}

void GmChannel::com90_loopMusic(void) {

      _channelData.eventDataPtr = _channelData.loopPoint;
}

void GmChannel::com90_keyOff(void) {

      _midiDrv->send((0x90 | _channelData.midiChannelNumber) | (_channelData.note << 8) | 0);
}

void GmChannel::com90_setLoopPoint(void) {

      _channelData.loopPoint = _channelData.eventDataPtr;
}

void GmChannel::com90_getChannelPanValue(void) {

      _midiDrv->send((0xB0 | _channelData.midiChannelNumber) | 0x0A00 | (_musicData[_channelData.eventDataPtr] << 16));
      _channelData.eventDataPtr++;
}

void GmChannel::com90_getChannelControl(void) {

      uint8 conNum = _musicData[_channelData.eventDataPtr++];
      uint8 conDat = _musicData[_channelData.eventDataPtr++];
      _midiDrv->send((0xB0 | _channelData.midiChannelNumber) | (conNum << 8) | (conDat << 16));
}

} // End of namespace Sky

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