more OPL preparation

DOES NOT WORK YET - JUST A PLACEHOLDER

src/engine/platform/opl.h

@@ -0,0 +1,120 @@
+/**
+ * Furnace Tracker - multi-system chiptune tracker
+ * Copyright (C) 2021-2022 tildearrow and contributors
+ *
+ * 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 2 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, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _OPL_H
+#define _OPL_H
+#include "../dispatch.h"
+#include "../macroInt.h"
+#include <queue>
+#include "../../../extern/Nuked-OPL3/opl3.h"
+
+class DivPlatformOPL: public DivDispatch {
+  protected:
+    struct Channel {
+      DivInstrumentFM state;
+      DivMacroInt std;
+      unsigned char freqH, freqL;
+      int freq, baseFreq, pitch, note;
+      unsigned char ins;
+      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, furnaceDac, inPorta;
+      int vol, outVol;
+      unsigned char pan;
+      Channel():
+        freqH(0),
+        freqL(0),
+        freq(0),
+        baseFreq(0),
+        pitch(0),
+        note(0),
+        ins(-1),
+        active(false),
+        insChanged(true),
+        freqChanged(false),
+        keyOn(false),
+        keyOff(false),
+        portaPause(false),
+        furnaceDac(false),
+        inPorta(false),
+        vol(0),
+        pan(3) {}
+    };
+    Channel chan[20];
+    bool isMuted[20];
+    struct QueuedWrite {
+      unsigned short addr;
+      unsigned char val;
+      bool addrOrVal;
+      QueuedWrite(unsigned short a, unsigned char v): addr(a), val(v), addrOrVal(false) {}
+    };
+    std::queue<QueuedWrite> writes;
+    opl3_chip fm;
+    int delay;
+    unsigned char lastBusy;
+
+    unsigned char regPool[512];
+  
+    bool dacMode;
+    int dacPeriod;
+    int dacRate;
+    unsigned int dacPos;
+    int dacSample;
+    unsigned char sampleBank;
+    unsigned char lfoValue;
+
+    bool extMode, useYMFM;
+    bool ladder;
+  
+    short oldWrites[512];
+    short pendingWrites[512];
+
+    int octave(int freq);
+    int toFreq(int freq);
+
+    friend void putDispatchChan(void*,int,int);
+
+    void acquire_nuked(short* bufL, short* bufR, size_t start, size_t len);
+    //void acquire_ymfm(short* bufL, short* bufR, size_t start, size_t len);
+  
+  public:
+    void acquire(short* bufL, short* bufR, size_t start, size_t len);
+    int dispatch(DivCommand c);
+    void* getChanState(int chan);
+    unsigned char* getRegisterPool();
+    int getRegisterPoolSize();
+    void reset();
+    void forceIns();
+    void tick();
+    void muteChannel(int ch, bool mute);
+    bool isStereo();
+    void setYMFM(bool use);
+    bool keyOffAffectsArp(int ch);
+    bool keyOffAffectsPorta(int ch);
+    void toggleRegisterDump(bool enable);
+    void setFlags(unsigned int flags);
+    void notifyInsChange(int ins);
+    void notifyInsDeletion(void* ins);
+    int getPortaFloor(int ch);
+    void poke(unsigned int addr, unsigned short val);
+    void poke(std::vector<DivRegWrite>& wlist);
+    const char* getEffectName(unsigned char effect);
+    int init(DivEngine* parent, int channels, int sugRate, unsigned int flags);
+    void quit();
+    ~DivPlatformOPL();
+};
+#endif