GA20: implement getSamplePos()

src/engine/platform/amiga.cpp

@@ -768,10 +768,12 @@ DivMacroInt* DivPlatformAmiga::getChanMacroInt(int ch) {
 DivSamplePos DivPlatformAmiga::getSamplePos(int ch) {
   if (ch>=4) return DivSamplePos();
   if (chan[ch].sample<0 || chan[ch].sample>=parent->song.sampleLen) return DivSamplePos();
+  int audPer=amiga.audPer[ch];
+  if (audPer<1) audPer=1;
   return DivSamplePos(
     chan[ch].sample,
     amiga.dmaLoc[ch]-sampleOff[chan[ch].sample],
-    chipClock/amiga.audPer[ch]
+    chipClock/audPer
   );
 }
 

src/engine/platform/ga20.cpp

@@ -336,6 +336,18 @@ DivMacroInt* DivPlatformGA20::getChanMacroInt(int ch) {
   return &chan[ch].std;
 }
 
+DivSamplePos DivPlatformGA20::getSamplePos(int ch) {
+  if (ch>=4) return DivSamplePos();
+  if (chan[ch].sample<0 || chan[ch].sample>=parent->song.sampleLen) return DivSamplePos();
+  if (!ga20.is_playing(ch)) return DivSamplePos();
+  unsigned char f=chan[ch].freq;
+  return DivSamplePos(
+    chan[ch].sample,
+    ga20.get_position(ch)-sampleOffGA20[chan[ch].sample],
+    chipClock/(4*(0x100-(int)f))
+  );
+}
+
 DivDispatchOscBuffer* DivPlatformGA20::getOscBuffer(int ch) {
   return oscBuf[ch];
 }

src/engine/platform/ga20.h

@@ -78,6 +78,7 @@ class DivPlatformGA20: public DivDispatch, public iremga20_intf {
     virtual int dispatch(DivCommand c) override;
     virtual void* getChanState(int chan) override;
     virtual DivMacroInt* getChanMacroInt(int ch) override;
+    virtual DivSamplePos getSamplePos(int ch) override;
     virtual DivDispatchOscBuffer* getOscBuffer(int chan) override;
     virtual unsigned char* getRegisterPool() override;
     virtual int getRegisterPoolSize() override;

src/engine/platform/sound/ga20/iremga20.h

@@ -39,12 +39,19 @@ public:
 	u8 read(u32 offset);
 
 	inline void set_mute(const int ch, const bool mute) { m_channel[ch & 3].mute = mute; }
+  inline unsigned int get_position(const int ch) {
+    return m_channel[ch&3].pos;
+  }
+  inline bool is_playing(const int ch) {
+    return m_channel[ch&3].play;
+  }
 
 	// device-level overrides
 	void device_reset();
 
 	// sound stream update overrides
 	void sound_stream_update(short** outputs, int len);
+  
 
 private:
 	struct channel_def