pcspk_pit.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 MADS_CORE_PCSPK_PIT_H
#define MADS_CORE_PCSPK_PIT_H
 
#include "common/array.h"
#include "common/scummsys.h"
 
namespace MADS {
 
class PCSpeakerPITRenderer {
public:
    explicit PCSpeakerPITRenderer(uint32 sampleRate,
        uint32 pitClock = 1193182);
    ~PCSpeakerPITRenderer();
 
    void advanceToSampleFraction(uint32 numerator, uint32 denominator);
    void writeMode3Count(uint16 count);
    void setControl(bool timerGate, bool speakerEnabled);
    int16 generateSample(byte volume);
 
private:
    class PCSpeakerOutputStage;
 
    enum {
        kFractionalPhases = 32,
        kImpulseDurationUs = 3125,
        kSampleFracBits = 24,
        kCoefficientFracBits = 30
    };
 
    void initializeImpulse();
    void resetState();
    void addTransition(int level, uint64 elapsedPitClocks = 0);
    void advanceCounter(uint64 pitClockUnits);
    bool isUndersampled(uint16 count) const;
    int outputLevel() const;
 
    uint32 _sampleRate;
    uint32 _pitClock;
    uint64 _phase;
    uint64 _samplePhase;
    uint64 _sampleCounter;
    uint16 _count;
    uint16 _pendingCount;
    bool _hasPendingCount;
    bool _counterLoaded;
    bool _timerGate;
    bool _speakerEnabled;
    bool _high;
    bool _undersampled;
    bool _hasUndersampledReload;
    uint64 _lastUndersampledReloadSample;
 
    uint32 _impulseLength;
    uint32 _impulseHead;
    Common::Array<int32> _impulseLut;
    Common::Array<int32> _impulseBuffer;
    int32 _reconstructedLevel;
    int _targetLevel;
    PCSpeakerOutputStage *_outputStage;
 
    PCSpeakerPITRenderer(const PCSpeakerPITRenderer &);
    PCSpeakerPITRenderer &operator=(const PCSpeakerPITRenderer &);
};
 
} // End of namespace MADS
 
#endif // MADS_CORE_PCSPK_PIT_H