pcm_common.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 PCM_COMMON_H
#define PCM_COMMON_H

#include "common/scummsys.h"

// The SegaCD and the FM-Towns have (almost) the same PCM sound chip. And while each platform has low-level driver
// stuff going on top of that it still makes sense to identify and abstract some commmon code.

class PCMChannel_Base {
public:
    PCMChannel_Base();
    virtual ~PCMChannel_Base();

    virtual void clear();

    void updateOutput();
    int32 currentSampleLeft();
    int32 currentSampleRight();

    virtual bool isPlaying() const = 0;
    bool isActive() const;
    void activate();
    void deactivate();

protected:
    void setData(const int8 *data, uint32 dataEnd, uint32 dataStart = 0);
    void setVolume(uint8 vol);
    void setPanPos(uint8 setPanPos);
    void setupLoop(uint32 loopStart, uint32 loopLen);
    void setRate(uint16 rate);

private:
    virtual void stopInternal() = 0;

    uint8 _panLeft;
    uint8 _panRight;
    uint8 _vol;
    bool _activeOutput;

    uint32 _loopStart;
    uint32 _loopLen;
    uint32 _dataEnd;
    uint32 _pos;
    uint16 _step;
    const int8 *_data;
};

class PCMDevice_Base {
public:
    PCMDevice_Base(int samplingRate, int deviceVolume, int numChannels);
    ~PCMDevice_Base();

    void assignChannel(uint8 id, PCMChannel_Base *const chan);
    void setMusicVolume(uint16 vol);
    void setSfxVolume(uint16 vol);
    void setSfxChanMask(int mask);

    void readBuffer(int32 *buffer, uint32 bufferSize);

private:
    const uint32 _intRate;
    const uint32 _extRate;
    const int _deviceVolume;
    uint32 _timer;

    uint16 _musicVolume;
    uint16 _sfxVolume;
    int _pcmSfxChanMask;

    PCMChannel_Base **_channels;
    const int _numChannels;
};

#endif