cms.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_SOFTSYNTH_CMS_H
#define AUDIO_SOFTSYNTH_CMS_H

#include "audio/cms.h"

/* this structure defines a channel */
struct saa1099_channel {
    int frequency;              /* frequency (0x00..0xff) */
    int freq_enable;            /* frequency enable */
    int noise_enable;           /* noise enable */
    int octave;             /* octave (0x00..0x07) */
    int amplitude[2];           /* amplitude (0x00..0x0f) */
    int envelope[2];            /* envelope (0x00..0x0f or 0x10 == off) */

    /* vars to simulate the square wave */
    int32 counter;
    int32 freq;
    int level;
};

/* this structure defines a noise channel */
struct saa1099_noise {
    /* vars to simulate the noise generator output */
    int32 counter;
    int32 freq;
    int level;              /* noise polynomal shifter */
};

/* this structure defines a SAA1099 chip */
struct SAA1099 {
    int stream;             /* our stream */
    int noise_params[2];            /* noise generators parameters */
    int env_enable[2];          /* envelope generators enable */
    int env_reverse_right[2];       /* envelope reversed for right channel */
    int env_mode[2];            /* envelope generators mode */
    int env_bits[2];            /* non zero = 3 bits resolution */
    int env_clock[2];           /* envelope clock mode (non-zero external) */
    int env_step[2];            /* current envelope step */
    int all_ch_enable;          /* all channels enable */
    int sync_state;             /* sync all channels */
    int selected_reg;           /* selected register */
    struct saa1099_channel channels[6]; /* channels */
    struct saa1099_noise noise[2];      /* noise generators */
};

class DOSBoxCMS : public ::CMS::CMS, public Audio::EmulatedChip {
public:
    DOSBoxCMS(uint32 basePort = 0x220) {
        memset(_saa1099, 0, sizeof(SAA1099)*2);
        _basePort = basePort;
    }

    ~DOSBoxCMS() override { }

    bool init() override;
    void reset() override;
    void write(int a, int v) override;
    void writeReg(int r, int v) override;

    bool isStereo() const override { return true; }

protected:
    void generateSamples(int16 *buffer, int numSamples) override;

private:
    uint32 _basePort;

    SAA1099 _saa1099[2];

    void envelope(int chip, int ch);
    void update(int chip, int16 *buffer, int length);
    void portWriteIntern(int chip, int offset, int data);
};


#endif