paula.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 AUDIO_MODS_PAULA_H
#define AUDIO_MODS_PAULA_H

#include "audio/audiostream.h"
#include "common/frac.h"
#include "common/mutex.h"

namespace Audio {

class Paula : public AudioStream {
public:
    static const int NUM_VOICES = 4;
    // Default panning value for left channels.
    static const int PANNING_LEFT = 63;
    // Default panning value for right channels.
    static const int PANNING_RIGHT = 191;
    enum {
        kPalSystemClock  = 7093790,
        kNtscSystemClock = 7159090,
        kPalCiaClock     = kPalSystemClock / 10,
        kNtscCiaClock    = kNtscSystemClock / 10,
        kPalPaulaClock   = kPalSystemClock / 2,
        kNtscPaulaClock  = kNtscSystemClock / 2
    };

    enum FilterMode {
        kFilterModeNone = 0,
        kFilterModeA500,
        kFilterModeA1200,

#if defined(__DS__)
        kFilterModeDefault = kFilterModeNone
#else
        kFilterModeDefault = kFilterModeA1200
#endif
    };

    /* TODO: Document this */
    struct Offset {
        uint    int_off;    // integral part of the offset
        frac_t  rem_off;    // fractional part of the offset, at least 0 and less than 1

        explicit Offset(int off = 0) : int_off(off), rem_off(0) {}
    };

    struct FilterState {
        FilterMode mode;
        bool ledFilter;

        float a0[3];
        float rc[NUM_VOICES][5];
    };

    Paula(bool stereo = false, int rate = 44100, uint interruptFreq = 0,
          FilterMode filterMode = kFilterModeDefault, int periodScaleDivisor = 1);
    ~Paula();

    bool playing() const { return _playing; }
    void setTimerBaseValue( uint32 ticksPerSecond ) { _timerBase = ticksPerSecond; }
    uint32 getTimerBaseValue() { return _timerBase; }
    void setSingleInterrupt(uint sampleDelay) { assert(sampleDelay < _intFreq); _curInt = sampleDelay; }
    void setSingleInterruptUnscaled(uint timerDelay) {
        setSingleInterrupt((uint)(((double)timerDelay * getRate()) / _timerBase));
    }
    void setInterruptFreq(uint sampleDelay) { _intFreq = sampleDelay; _curInt = 0; }
    void setInterruptFreqUnscaled(uint timerDelay) {
        setInterruptFreq((uint)(((double)timerDelay * getRate()) / _timerBase));
    }
    void clearVoice(byte voice);
    void clearVoices() { for (int i = 0; i < NUM_VOICES; ++i) clearVoice(i); }
    void startPlay() { filterResetState(); _playing = true; }
    void stopPlay() { _playing = false; }
    void pausePlay(bool pause) { _playing = !pause; }

// AudioStream API
    int readBuffer(int16 *buffer, const int numSamples);
    bool isStereo() const { return _stereo; }
    bool endOfData() const { return _end; }
    int getRate() const { return _rate; }

protected:
    struct Channel {
        const int8 *data;
        const int8 *dataRepeat;
        uint32 length;
        uint32 lengthRepeat;
        int16 period;
        byte volume;
        Offset offset;
        byte panning; // For stereo mixing: 0 = far left, 255 = far right
        int dmaCount;
        bool interrupt;
    };

    bool _end;
    Common::Mutex &_mutex;

    virtual void interrupt() = 0;

    virtual void interruptChannel(byte channel) { }

    void startPaula() {
        _playing = true;
        _end = false;
    }

    void stopPaula() {
        _playing = false;
        _end = true;
    }

    void setChannelPanning(byte channel, byte panning) {
        assert(channel < NUM_VOICES);
        _voice[channel].panning = panning;
    }

    void disableChannel(byte channel) {
        assert(channel < NUM_VOICES);
        _voice[channel].data = 0;
    }

    void enableChannel(byte channel) {
        assert(channel < NUM_VOICES);
        Channel &ch = _voice[channel];
        ch.data = ch.dataRepeat;
        ch.length = ch.lengthRepeat;
        // actually first 2 bytes are dropped?
        ch.offset = Offset(0);
        // ch.period = ch.periodRepeat;
    }

    void setChannelInterrupt(byte channel, bool enable) {
        assert(channel < NUM_VOICES);
        _voice[channel].interrupt = enable;
    }

    void setChannelPeriod(byte channel, int16 period) {
        assert(channel < NUM_VOICES);
        _voice[channel].period = period;
    }

    void setChannelVolume(byte channel, byte volume) {
        assert(channel < NUM_VOICES);
        _voice[channel].volume = volume;
    }

    void setChannelSampleStart(byte channel, const int8 *data) {
        assert(channel < NUM_VOICES);
        _voice[channel].dataRepeat = data;
    }

    void setChannelSampleLen(byte channel, uint32 length) {
        assert(channel < NUM_VOICES);
        assert(length < 32768/2);
        _voice[channel].lengthRepeat = 2 * length;
    }

    void setChannelData(uint8 channel, const int8 *data, const int8 *dataRepeat, uint32 length, uint32 lengthRepeat, int32 offset = 0) {
        assert(channel < NUM_VOICES);

        Channel &ch = _voice[channel];

        ch.dataRepeat = data;
        ch.lengthRepeat = length;
        enableChannel(channel);
        ch.offset = Offset(offset);

        ch.dataRepeat = dataRepeat;
        ch.lengthRepeat = lengthRepeat;
    }

    void setChannelOffset(byte channel, Offset offset) {
        assert(channel < NUM_VOICES);
        _voice[channel].offset = offset;
    }

    Offset getChannelOffset(byte channel) {
        assert(channel < NUM_VOICES);
        return _voice[channel].offset;
    }

    int getChannelDmaCount(byte channel) {
        assert(channel < NUM_VOICES);
        return _voice[channel].dmaCount;
    }

    void setChannelDmaCount(byte channel, int dmaVal = 0) {
        assert(channel < NUM_VOICES);
        _voice[channel].dmaCount = dmaVal;
    }

    void setAudioFilter(bool enable) {
        _filterState.ledFilter = enable;
    }

private:
    Channel _voice[NUM_VOICES];

    const bool _stereo;
    const int _rate;
    const double _periodScale;
    uint _intFreq;
    uint _curInt;
    uint32 _timerBase;
    bool _playing;

    FilterState _filterState;

    template<bool stereo>
    int readBufferIntern(int16 *buffer, const int numSamples);

    void filterResetState();
    float filterCalculateA0(int rate, int cutoff);
};

} // End of namespace Audio

#endif