towns_pc98_fmsynth.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 TOWNS_PC98_FMSYNTH_H
#define TOWNS_PC98_FMSYNTH_H

#include "audio/audiostream.h"
#include "audio/mixer.h"
#include "common/mutex.h"
#include "common/func.h"
#include "common/array.h"

#ifdef __DS__
/* This disables the rhythm channel when emulating the PC-98 type 86 sound card.
 * The only purpose is code size reduction for certain backends.
 * At the moment the only games which make use of the rhythm channel are the
 * (very rare) PC-98 versions of Legend of Kyrandia 2 and Lands of Lore. Music will
 * still be okay, just missing a couple of rhythm instruments.
 */
#define     DISABLE_PC98_RHYTHM_CHANNEL
#endif

/* Experimental code for emulation of the chip's busy flag wait cycle.
 * Explanation:
 * Before attempting a port write a client application would usually read the chip's
 * busy flag and remain in a loop until the flag is cleared. This does not work with
 * an emulator that is on the same thread as the client code (the busy flag will never
 * clear). Instead, I emulate a wait cycle by withholding (enqueueing) incoming register
 * writes for the duration of the wait cycle.
 * For now I have disabled this with an #ifdef since I haven't seen any impact on the
 * sound.
 */
//#define       ENABLE_SNDTOWNS98_WAITCYCLES

class TownsPC98_FmSynthOperator;
class TownsPC98_FmSynthSquareWaveSource;
#ifndef DISABLE_PC98_RHYTHM_CHANNEL
class TownsPC98_FmSynthPercussionSource;
#endif

enum EnvelopeState {
    kEnvReady = 0,
    kEnvAttacking,
    kEnvDecaying,
    kEnvSustaining,
    kEnvReleasing
};

class TownsPC98_FmSynth : public Audio::AudioStream {
public:
    enum EmuType {
        kTypeTowns = 0,
        kType26 = 1,
        kType86 = 2
    };

    TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type);
    virtual ~TownsPC98_FmSynth();

    virtual bool init();
    virtual void reset();

    void writeReg(uint8 part, uint8 regAddress, uint8 value);
    uint8 readReg(uint8 part, uint8 regAddress);

    // AudioStream interface
    int readBuffer(int16 *buffer, const int numSamples);
    bool isStereo() const;
    bool endOfData() const;
    int getRate() const;

protected:
    void deinit();

    // Implement this in your inherited class if your driver generates
    // additional output that has to be inserted into the buffer.
    virtual void nextTickEx(int32 *buffer, uint32 bufferSize) {}

    virtual void timerCallbackA() = 0;
    virtual void timerCallbackB() = 0;

    // The audio driver can store and apply two different volume settings
    // (usually for music and sound effects). The channel mask will determine
    // which channels get effected by which setting. The first bits will be
    // the normal fm channels, the next bits the ssg channels and the final
    // bit the rhythm channel.
    void setVolumeIntern(int volA, int volB);
    void setVolumeChannelMasks(int channelMaskA, int channelMaskB);

    // This allows to balance out the fm/ssg levels.
    void setLevelSSG(int vol);

    const int _numChan;
    const int _numSSG;
    const bool _hasPercussion;

    Common::Mutex &_mutex;
    int _mixerThreadLockCounter;

private:
    void generateTables();
    void writeRegInternal(uint8 part, uint8 regAddress, uint8 value);
    void nextTick(int32 *buffer, uint32 bufferSize);

#ifdef ENABLE_SNDTOWNS98_WAITCYCLES
    void startWaitCycle();
#endif

    struct ChanInternal {
        ChanInternal() = default;
        ChanInternal(const ChanInternal &) = delete;
        ChanInternal(ChanInternal &&) = delete;
        ChanInternal &operator=(const ChanInternal &) = delete;
        ChanInternal &operator=(ChanInternal &&) = delete;
        ~ChanInternal();

        void ampModSensitivity(uint32 value) {
            ampModSvty = (1 << (3 - value)) - (((value >> 1) & 1) | (value & 1));
        }
        void frqModSensitivity(uint32 value) {
            frqModSvty = value << 5;
        }
        void fbClear() {
            feedbuf[0] = feedbuf[1] = feedbuf[2] = 0;
        }

        bool enableLeft = false;
        bool enableRight = false;
        bool updateEnvelopeParameters = false;
        int32 feedbuf[3] = {};
        uint8 algorithm = 0u;

        uint32 ampModSvty = 0u;
        uint32 frqModSvty = 0u;

        TownsPC98_FmSynthOperator *opr[4] = {};
    };

    TownsPC98_FmSynthSquareWaveSource *_ssg;
#ifndef DISABLE_PC98_RHYTHM_CHANNEL
    TownsPC98_FmSynthPercussionSource *_prc;
#endif
    ChanInternal *_chanInternal;

    uint8 *_oprRates;
    uint8 *_oprRateshift;
    uint8 *_oprAttackDecay;
    uint32 *_oprFrq;
    uint32 *_oprSinTbl;
    int32 *_oprLevelOut;
    int32 *_oprDetune;

    typedef Common::Functor0Mem<void, TownsPC98_FmSynth> ChipTimerProc;
    ChipTimerProc *_timerProcIdle;
    ChipTimerProc *_timerProcA;
    ChipTimerProc *_timerProcB;
    void idleTimerCallback() {}

    struct ChipTimer {
        bool enabled;
        uint16 value;

        int32 smpTillCb;
        uint32 smpTillCbRem;
        int32 smpPerCb;
        uint32 smpPerCbRem;

        ChipTimerProc *cb;
    };

    ChipTimer _timers[2];

    int _volMaskA, _volMaskB;
    uint16 _volumeA, _volumeB;

    int32 *_renderBuffer;
    int _renderBufferSize;
    int _numPending;
    int _offsPending;
    int _rateScale;
    int _outRateMult;
    int _rateConvCnt;
    float _predSmpCount;
    const int _internalRate;
    const int _outputRate;

#ifdef  ENABLE_SNDTOWNS98_WAITCYCLES
    int _waitCycleRemainder;
    const int _samplesPerWaitCycle;

    struct RegEntry {
        RegEntry(uint8 p, uint8 r, uint8 v) : part(p), reg(r), val(v) {}
        uint8 part;
        uint8 reg;
        uint8 val;
    };

    Common::Array<RegEntry> _waitCycleElapsedWrites;
#endif

    uint8 _registers[255][2];

    Audio::Mixer *_mixer;
    Audio::SoundHandle _soundHandle;

#ifndef DISABLE_PC98_RHYTHM_CHANNEL
    static const uint8 _percussionData[];
#endif
    static const uint32 _adtStat[];
    static const uint8 _detSrc[];
    static const int _ssgTables[];

    bool _ready;
};

#endif