cms.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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef AGOS_DRIVERS_ACCOLADE_CMS_H
#define AGOS_DRIVERS_ACCOLADE_CMS_H

#include "audio/mididrv.h"

#include "audio/cms.h"

namespace AGOS {

// MIDI driver for the Creative Music System / Gameblaster.
// This driver uses only 6 of the available 12 channels and does not support
// stereo. It only supports note on and off and program change; the selected
// instrument only affects the note volume.
class MidiDriver_Accolade_Cms : public MidiDriver {
protected:
    static const byte REGISTER_BASE_AMPLITUDE = 0x00;
    static const byte REGISTER_BASE_FREQUENCY = 0x08;
    static const byte REGISTER_BASE_OCTAVE = 0x10;
    static const byte REGISTER_FREQUENCY_ENABLE = 0x14;
    static const byte REGISTER_RESET_SOUND_ENABLE = 0x1C;

    // Frequency register values for octave notes.
    static const byte CMS_NOTE_FREQUENCIES[12];
    // Volume adjustments for all instruments.
    static const byte CMS_VOLUME_ADJUSTMENTS[128];

public:
    MidiDriver_Accolade_Cms();
    ~MidiDriver_Accolade_Cms() override;

    int open() override;
    void close() override;
    bool isOpen() const override;
    uint32 getBaseTempo() override;
    // This driver does not support MidiChannel objects.
    MidiChannel *allocateChannel() override;
    // This driver does not support MidiChannel objects.
    MidiChannel *getPercussionChannel() override;

    using MidiDriver::send;
    void send(uint32 b) override;

    void setTimerCallback(void *timer_param, Common::TimerManager::TimerProc timer_proc) override;
    void onTimer();

protected:
    void cmsInit();

    void noteOff(uint8 channel, uint8 note);
    void noteOn(uint8 channel, uint8 note, uint8 velocity);
    void programChange(uint8 channel, uint8 instrument);
    void controlChange(uint8 channel, uint8 controller, uint8 value);

    // Returns the value for the frequency enable register of the first CMS
    // chip based on the _activeNotes array (if a note is active, the bit for
    // the corresponding channel is set).
    byte determineFrequencyEnableRegisterValue();
    void writeRegister(uint16 reg, uint8 value);

    CMS::CMS *_cms;
    bool _isOpen;

    // The selected instrument on each MIDI channel.
    byte _instruments[16];
    // The active note on each CMS channel (0xFF if no note is active).
    byte _activeNotes[12];
    // The current values of the CMS octave registers (0x10 - 0x12).
    byte _octaveRegisterValues[6];

    // External timer callback
    void *_timer_param;
    Common::TimerManager::TimerProc _timer_proc;
};

} // End of namespace AGOS

#endif