player_apple2.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 SCUMM_PLAYERS_PLAYER_APPLEII_H
#define SCUMM_PLAYERS_PLAYER_APPLEII_H

#include "common/mutex.h"
#include "common/scummsys.h"
#include "scumm/music.h"
#include "audio/audiostream.h"
#include "audio/mixer.h"

namespace Scumm {

class ScummEngine;

/*
 * Optimized for use with periodical read/write phases when the buffer
 * is filled in a write phase and completely read in a read phase.
 * The growing strategy is optimized for repeated small (e.g. 2 bytes)
 * single writes resulting in large buffers
 * (avg.: 4KB, max: 18KB @ 16bit/22.050kHz (MM sound21)).
 */
class SampleBuffer {
public:
    SampleBuffer() : _data(0) {
        clear();
    }

    ~SampleBuffer() {
        free(_data);
    }

    void clear() {
        free(_data);
        _data = 0;
        _capacity = 0;
        _writePos = 0;
        _readPos = 0;
    }

    void ensureFree(uint32 needed) {
        // if data was read completely, reset read/write pos to front
        if ((_writePos != 0) && (_writePos == _readPos)) {
            _writePos = 0;
            _readPos = 0;
        }

        // check for enough space at end of buffer
        uint32 freeEndCnt = _capacity - _writePos;
        if (needed <= freeEndCnt)
            return;

        uint32 avail = availableSize();

        // check for enough space at beginning and end of buffer
        if (needed <= _readPos + freeEndCnt) {
            // move unread data to front of buffer
            memmove(_data, _data + _readPos, avail);
            _writePos = avail;
            _readPos = 0;
        } else { // needs a grow
            byte *old_data = _data;
            uint32 new_len = avail + needed;

            _capacity = new_len + 2048;
            _data = (byte *)malloc(_capacity);

            if (old_data) {
                // copy old unread data to front of new buffer
                memcpy(_data, old_data + _readPos, avail);
                free(old_data);
                _writePos = avail;
                _readPos = 0;
            }
        }
    }

    uint32 availableSize() const {
        if (_readPos >= _writePos)
            return 0;
        return _writePos - _readPos;
    }

    uint32 write(const void *dataPtr, uint32 dataSize) {
        ensureFree(dataSize);
        memcpy(_data + _writePos, dataPtr, dataSize);
        _writePos += dataSize;
        return dataSize;
    }

    uint32 read(byte *dataPtr, uint32 dataSize) {
        uint32 avail = availableSize();
        if (avail == 0)
            return 0;
        if (dataSize > avail)
            dataSize = avail;
        memcpy(dataPtr, _data + _readPos, dataSize);
        _readPos += dataSize;
        return dataSize;
    }

private:
    uint32 _writePos;
    uint32 _readPos;
    uint32 _capacity;
    byte *_data;
};

// CPU_CLOCK according to AppleWin
static const double APPLEII_CPU_CLOCK = 1020484.5; // ~ 1.02 MHz

/*
 * Converts the 1-bit speaker state values into audio samples.
 * This is done by aggregation of the speaker states at each
 * CPU cycle in a sampling period into an audio sample.
 */
class SampleConverter {
private:
    void addSampleToBuffer(int sample) {
        int16 value = sample * _volume / _maxVolume;
        _buffer.write(&value, sizeof(value));
    }

public:
    SampleConverter() :
        _cyclesPerSampleFP(0),
        _missingCyclesFP(0),
        _sampleCyclesSumFP(0),
        _volume(_maxVolume)
    {}

    ~SampleConverter() {}

    void reset() {
        _missingCyclesFP = 0;
        _sampleCyclesSumFP = 0;
        _buffer.clear();
    }

    uint32 availableSize() const {
        return _buffer.availableSize();
    }

    void setMusicVolume(int vol) {
        assert(vol >= 0 && vol <= _maxVolume);
        _volume = vol;
    }

    void setSampleRate(int rate) {
        /* ~46 CPU cycles per sample @ 22.05kHz */
        _cyclesPerSampleFP = int(APPLEII_CPU_CLOCK * (1 << PREC_SHIFT) / rate);
        reset();
    }

    void addCycles(byte level, const int cycles) {
        /* convert to fixed precision floats */
        int cyclesFP = cycles << PREC_SHIFT;

        // step 1: if cycles are left from the last call, process them first
        if (_missingCyclesFP > 0) {
            int n = (_missingCyclesFP < cyclesFP) ? _missingCyclesFP : cyclesFP;
            if (level)
                _sampleCyclesSumFP += n;
            cyclesFP -= n;
            _missingCyclesFP -= n;
            if (_missingCyclesFP == 0) {
                addSampleToBuffer(2*32767 * _sampleCyclesSumFP / _cyclesPerSampleFP - 32767);
            } else {
                return;
            }
        }

        _sampleCyclesSumFP = 0;

        // step 2: process blocks of cycles fitting into a whole sample
        while (cyclesFP >= _cyclesPerSampleFP) {
            addSampleToBuffer(level ? 32767 : -32767);
            cyclesFP -= _cyclesPerSampleFP;
        }

        // step 3: remember cycles left for next call
        if (cyclesFP > 0) {
            _missingCyclesFP = _cyclesPerSampleFP - cyclesFP;
            if (level)
                _sampleCyclesSumFP = cyclesFP;
        }
    }

    uint32 readSamples(void *buffer, int numSamples) {
        return _buffer.read((byte *)buffer, numSamples * 2) / 2;
    }

private:
    static const int PREC_SHIFT = 7;

private:
    int _cyclesPerSampleFP;   /* (fixed precision) */
    int _missingCyclesFP;     /* (fixed precision) */
    int _sampleCyclesSumFP;   /* (fixed precision) */
    int _volume; /* 0 - 256 */
    static const int _maxVolume = 256;
    SampleBuffer _buffer;
};

class Player_AppleII;

class AppleII_SoundFunction {
public:
    AppleII_SoundFunction() {}
    virtual ~AppleII_SoundFunction() {}
    virtual void init(Player_AppleII *player, const byte *params) = 0;
    /* returns true if finished */
    virtual bool update() = 0;
protected:
    Player_AppleII *_player = nullptr;
};

class Player_AppleII : public Audio::AudioStream, public MusicEngine {
public:
    Player_AppleII(ScummEngine *scumm, Audio::Mixer *mixer);
    ~Player_AppleII() override;

    void setMusicVolume(int vol) override { _sampleConverter.setMusicVolume(vol); }
    void setSampleRate(int rate) {
        _sampleRate = rate;
        _sampleConverter.setSampleRate(rate);
    }
    void startSound(int sound) override;
    void stopSound(int sound) override;
    void stopAllSounds() override;
    int  getSoundStatus(int sound) const override;
    int  getMusicTimer() override;

    // AudioStream API
    int readBuffer(int16 *buffer, const int numSamples) override;
    bool isStereo() const override { return false; }
    bool endOfData() const override { return false; }
    int getRate() const override { return _sampleRate; }

public:
    void speakerToggle();
    void generateSamples(int cycles);
    void wait(int interval, int count);

private:
    // sound number
    int _soundNr = 0;
    // type of sound
    int _type = 0;
    // number of loops left
    int _loop = 0;
    // global sound param list
    const byte *_params = nullptr;
    // speaker toggle state (0 / 1)
    byte _speakerState = 0;
    // sound function
    AppleII_SoundFunction *_soundFunc;
    // cycle to sample converter
    SampleConverter _sampleConverter;

    ScummEngine *_vm;
    Audio::Mixer *_mixer;
    Audio::SoundHandle _soundHandle;
    int _sampleRate = 0;
    Common::Mutex _mutex;

    void resetState();
    bool updateSound();
};

} // End of namespace Scumm

#endif