Reduce duplicates of channel struct

Add/Fix custom clock limit defines (for YMF278B)

src/engine/platform/arcade.h

@@ -20,8 +20,6 @@
 #ifndef _ARCADE_H
 #define _ARCADE_H
 #include "fmshared_OPM.h"
-#include "../macroInt.h"
-#include "../instrument.h"
 #include <queue>
 #include "../../../extern/opm/opm.h"
 #include "sound/ymfm/ymfm_opm.h"
@@ -36,44 +34,12 @@ class DivPlatformArcade: public DivPlatformOPM {
       0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07
     };
 
-    struct Channel {
-      DivInstrumentFM state;
-      DivMacroInt std;
-      unsigned char freqH, freqL;
-      int freq, baseFreq, pitch, pitch2, note;
-      int ins;
-      signed char konCycles;
-      bool active, insChanged, freqChanged, keyOn, keyOff, inPorta, portaPause, furnacePCM, hardReset, opMaskChanged;
-      int vol, outVol;
-      unsigned char chVolL, chVolR, opMask;
-      void macroInit(DivInstrument* which) {
-        std.init(which);
-        pitch2=0;
-      }
+    struct Channel: public FMChannel {
+      unsigned char chVolL, chVolR;
       Channel():
-        freqH(0),
-        freqL(0),
-        freq(0),
-        baseFreq(0),
-        pitch(0),
-        pitch2(0),
-        note(0),
-        ins(-1),
-        active(false),
-        insChanged(true),
-        freqChanged(false),
-        keyOn(false),
-        keyOff(false),
-        inPorta(false),
-        portaPause(false),
-        furnacePCM(false),
-        hardReset(false),
-        opMaskChanged(false),
-        vol(0),
-        outVol(0),
-        chVolL(127),
-        chVolR(127),
-        opMask(15) {}
+        FMChannel(),
+        chVolL(1),
+        chVolR(1) {}
     };
     Channel chan[8];
     DivDispatchOscBuffer* oscBuf[8];