Add VIC-20 support

src/engine/platform/vic20.h

@@ -0,0 +1,86 @@
+/**
+ * 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 _VIC20_H
+#define _VIC20_H
+
+#include "../dispatch.h"
+#include "../macroInt.h"
+#include "sound/vic20sound.h"
+#include <queue>
+
+class DivPlatformVIC20: public DivDispatch {
+  struct Channel {
+    int freq, baseFreq, pitch, note;
+    unsigned char ins, pan;
+    bool active, insChanged, freqChanged, keyOn, keyOff, inPorta;
+    int vol, outVol, wave, waveWriteCycle;
+    DivMacroInt std;
+    Channel():
+      freq(0),
+      baseFreq(0),
+      pitch(0),
+      note(0),
+      ins(-1),
+      pan(255),
+      active(false),
+      insChanged(true),
+      freqChanged(false),
+      keyOn(false),
+      keyOff(false),
+      inPorta(false),
+      vol(15),
+      outVol(15),
+      wave(0),
+      waveWriteCycle(-1) {}
+  };
+  Channel chan[4];
+  bool isMuted[4];
+  bool hasWaveWrite;
+
+  unsigned char regPool[16];
+  sound_vic20_t* vic;
+  void updateWave(int ch);
+  friend void putDispatchChan(void*,int,int);
+  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);
+    void setFlags(unsigned int flags);
+    void notifyInsDeletion(void* ins);
+    bool isStereo();
+    void poke(unsigned int addr, unsigned short val);
+    void poke(std::vector<DivRegWrite>& wlist);
+    const char** getRegisterSheet();
+    const char* getEffectName(unsigned char effect);
+    int init(DivEngine* parent, int channels, int sugRate, unsigned int flags);
+    void quit();
+    ~DivPlatformVIC20();
+  private:
+    void calcAndWriteOutVol(int ch, int env);
+    void writeOutVol(int ch);
+};
+
+#endif