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midiparser_s1d.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-1-1-1/engines/agos/midiparser_s1d.cpp $
 * $Id: midiparser_s1d.cpp 42606 2009-07-19 09:09:56Z Kirben $
 *
 */

#include "common/debug.h"
#include "common/util.h"

#include "sound/mididrv.h"
#include "sound/midiparser.h"

namespace AGOS {

/**
 * Simon 1 Demo version of MidiParser.
 *
 * This parser is the result of eyeballing the one MUS file that's included
 * with simon1demo. So there might be some things missing. I've tried to notate
 * question-mark areas where they occur.
 */
00041 class MidiParser_S1D : public MidiParser {
protected:
      byte *_data;
      bool _no_delta;

protected:
      void parseNextEvent(EventInfo &info);
      void resetTracking();
      uint32 readVLQ2(byte * &data);

public:
      MidiParser_S1D() : _data(0), _no_delta(false) {}

      bool loadMusic(byte *data, uint32 size);
};


// The VLQs for simon1demo seem to be
// in Little Endian format.
uint32 MidiParser_S1D::readVLQ2(byte * &data) {
      byte str;
      uint32 value = 0;
      int i;

      for (i = 0; i < 4; ++i) {
            str = data[0];
            ++data;
            value |= (str & 0x7F) << (i * 7);
            if (!(str & 0x80))
                  break;
      }
      return value;
}

void MidiParser_S1D::parseNextEvent(EventInfo &info) {
      info.start = _position._play_pos;
      info.delta = _no_delta ? 0 : readVLQ2(_position._play_pos);

      _no_delta = false;
      info.event = *(_position._play_pos++);
      if (info.command() < 0x8) {
            _no_delta = true;
            info.event += 0x80;
      }

      switch (info.command()) {
      case 0x8:
            info.basic.param1 = *(_position._play_pos++);
            info.basic.param2 = 0;
            info.length = 0;
            break;

      case 0x9:
            info.basic.param1 = *(_position._play_pos++);
            info.basic.param2 = *(_position._play_pos++); // I'm ASSUMING this byte is velocity!
            info.length = 0;
            break;

      case 0xA:
      case 0xB:
            // I'm not sure what these are meant to do, or what the
            // parameter is. Elvira 1 needs them, though, and who am I to
            // argue with her?
            info.basic.param1 = *(_position._play_pos++);
            info.basic.param2 = 0;
            break;

      case 0xC:
            info.basic.param1 = *(_position._play_pos++);
            info.basic.param2 = 0;
            ++_position._play_pos; // I have NO IDEA what the second byte is for.
            break;

      case 0xD:
            // Triggered by MOD0/MOD1/MOD2/MOD3/MOD4/MOD6/MOD7/MOD8/MOD9 in Elvira 2
            // Triggered by MOD0/MOD2/MOD3/MOD5/MOD6/MOD7/MOD8/MOD9/MOD10/MOD12/MOD14/MOD15/MOD20 in Waxworks
            break;

      case 0xE:
            // Triggered by MOD9 in Elvira 1
            // Triggered by MOD3/MOD5 in Elvira 2
            // Triggered by MOD3/MOD7/MOD8/MOD13 in Waxworks
            break;

      case 0xF:
            switch (info.event & 0x0F) {
            case 0x0:
                  // Trigged by MOD2/MOD6/MOD15 in Waxworks
                  // Pure guesswork
                  info.ext.type = *(_position._play_pos++);
                  info.length = readVLQ(_position._play_pos);
                  info.ext.data = _position._play_pos;
                  break;

            case 0x3: // Not sure, Song Select?
                  // Trigged by MOD1/MOD7/MOD10 in Elvira 1
                  info.basic.param1 = *(_position._play_pos++);
                  info.basic.param2 = 0;
                  break;

            case 0x4:
                  // Trigged by MOD8 in Elvira 1
                  break;

            case 0x7:
                  // Trigged by MOD6 in Elvira 2
                  // Trigged by MOD5 in Waxworks
                  break;

            case 0x8: // Not sure, ?
                  // Trigged by MOD19 in Waxworks
                  info.basic.param1 = info.basic.param2 = 0;
                  break;

            case 0xA:
                  // Trigged by MOD5 in Elvira 2
                  break;

            case 0xC:
                  // This means End of Track.
                  // Rewrite in SMF (MIDI transmission) form.
                  info.event = 0xFF;
                  info.ext.type = 0x2F;
                  info.length = 0;
                  break;

            case 0xF: // Not sure, META event?
                  // Trigged by MOD8/MOD9/MOD11/MOD12/MOD13 in Waxworks
                  info.ext.type = *(_position._play_pos++);
                  info.length = readVLQ(_position._play_pos);
                  info.ext.data = _position._play_pos;
                  _position._play_pos += info.length;
                  break;

            default:
                  error("MidiParser_S1D: Unexpected type 0x%02X found", (int) info.event);
                  break;
            }
            break;
      default:
            error("MidiParser_S1D: Unexpected event 0x%02X found", (int) info.command());
            break;
      }
}

bool MidiParser_S1D::loadMusic(byte *data, uint32 size) {
      unloadMusic();

      byte *pos = data;
      if (*(pos++) != 0xFC)
            debug(1, "Expected 0xFC header but found 0x%02X instead", (int) *pos);

      // The next 3 bytes MIGHT be tempo, but we skip them and use the default.
//    setTempo (*(pos++) | (*(pos++) << 8) | (*(pos++) << 16));
      pos += 3;

      // And now we're at the actual data. Only one track.
      _num_tracks = 1;
      _data = pos;
      _tracks[0] = pos;

      // Note that we assume the original data passed in
      // will persist beyond this call, i.e. we do NOT
      // copy the data to our own buffer. Take warning....
      resetTracking();
      setTempo(666667);
      setTrack(0);
      return true;
}

void MidiParser_S1D::resetTracking() {
      MidiParser::resetTracking();
      _no_delta = false;
}

MidiParser *MidiParser_createS1D() { return new MidiParser_S1D; }

} // End of namespace AGOS

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