implement getGain for a couple chips

the ones with log volume

src/engine/engine.cpp

@@ -2330,6 +2330,13 @@ int DivEngine::mapVelocity(int ch, float vel) {
   return disCont[dispatchOfChan[ch]].dispatch->mapVelocity(dispatchChanOfChan[ch],vel);
 }
 
+float DivEngine::getGain(int ch, int vol) {
+  if (ch<0) return 0;
+  if (ch>=chans) return 0;
+  if (disCont[dispatchOfChan[ch]].dispatch==NULL) return 0;
+  return disCont[dispatchOfChan[ch]].dispatch->getGain(dispatchChanOfChan[ch],vol);
+}
+
 unsigned char DivEngine::getOrder() {
   return prevOrder;
 }

src/engine/engine.h

@@ -927,6 +927,9 @@ class DivEngine {
     // map MIDI velocity to volume
     int mapVelocity(int ch, float vel);
 
+    // map volume to gain
+    float getGain(int ch, int vol);
+
     // get current order
     unsigned char getOrder();
 

src/engine/platform/ay.cpp

@@ -801,6 +801,11 @@ int DivPlatformAY8910::mapVelocity(int ch, float vel) {
   return round(15.0*pow(vel,0.33));
 }
 
+float DivPlatformAY8910::getGain(int ch, int vol) {
+  if (vol==0) return 0;
+  return 1.0/pow(10.0,(float)(15-vol)*2.0/20.0);
+}
+
 unsigned char* DivPlatformAY8910::getRegisterPool() {
   return regPool;
 }

src/engine/platform/ay.h

@@ -144,6 +144,7 @@ class DivPlatformAY8910: public DivDispatch {
     void* getChanState(int chan);
     DivDispatchOscBuffer* getOscBuffer(int chan);
     int mapVelocity(int ch, float vel);
+    float getGain(int ch, int vol);
     unsigned char* getRegisterPool();
     int getRegisterPoolSize();
     void setCore(unsigned char core);

src/engine/platform/ay8930.cpp

@@ -792,6 +792,11 @@ int DivPlatformAY8930::mapVelocity(int ch, float vel) {
   return round(31.0*pow(vel,0.22));
 }
 
+float DivPlatformAY8930::getGain(int ch, int vol) {
+  if (vol==0) return 0;
+  return 1.0/pow(10.0,(float)(31-vol)*1.5/20.0);
+}
+
 unsigned char* DivPlatformAY8930::getRegisterPool() {
   return regPool;
 }

src/engine/platform/ay8930.h

@@ -138,6 +138,7 @@ class DivPlatformAY8930: public DivDispatch {
     void* getChanState(int chan);
     DivDispatchOscBuffer* getOscBuffer(int chan);
     int mapVelocity(int ch, float vel);
+    float getGain(int ch, int vol);
     unsigned char* getRegisterPool();
     int getRegisterPoolSize();
     void reset();

src/engine/platform/fmshared_OPN.h

@@ -198,6 +198,19 @@ class DivPlatformOPN: public DivPlatformFMBase {
       if (ch>=psgChanOffs) return round(15.0*pow(vel,0.33));
       return DivPlatformFMBase::mapVelocity(ch,vel);
     }
+    virtual float getGain(int ch, int vol) {
+      if (vol==0) return 0;
+      if (ch==csmChan) return 1;
+      if (ch==adpcmBChanOffs) return (float)vol/255.0;
+      if (ch>=adpcmAChanOffs) {
+        return 1.0/pow(10.0,(float)(31-vol)*0.75/20.0);
+      }
+      if (ch>=psgChanOffs) {
+        return 1.0/pow(10.0,(float)(15-vol)*1.5/20.0);
+      }
+      return DivPlatformFMBase::getGain(ch,vol);
+    }
+
 };
 
 #endif

src/engine/platform/fmsharedbase.h

@@ -136,6 +136,11 @@ class DivPlatformFMBase: public DivDispatch {
       return CLAMP(round(128.0-(56.0-log2(vel*127.0)*8.0)),0,127);
     }
 
+    virtual float getGain(int ch, int vol) {
+      if (vol==0) return 0;
+      return 1.0/pow(10.0,(float)(127-vol)*0.75/20.0);
+    }
+
     bool getLegacyAlwaysSetVolume() {
       return true;
     }

src/engine/platform/opl.cpp

@@ -2140,6 +2140,11 @@ int DivPlatformOPL::mapVelocity(int ch, float vel) {
   return CLAMP(round(64.0-(56.0-log2(vel*127.0)*8.0)),0,63);
 }
 
+float DivPlatformOPL::getGain(int ch, int vol) {
+  if (vol==0) return 0;
+  return 1.0/pow(10.0,(float)(63-vol)*0.75/20.0);
+}
+
 unsigned char* DivPlatformOPL::getRegisterPool() {
   return regPool;
 }

src/engine/platform/opl.h

@@ -154,6 +154,7 @@ class DivPlatformOPL: public DivDispatch {
     DivChannelPair getPaired(int chan);
     DivDispatchOscBuffer* getOscBuffer(int chan);
     int mapVelocity(int ch, float vel);
+    float getGain(int ch, int vol);
     unsigned char* getRegisterPool();
     int getRegisterPoolSize();
     void reset();

src/engine/platform/opll.cpp

@@ -1026,6 +1026,11 @@ int DivPlatformOPLL::mapVelocity(int ch, float vel) {
   return CLAMP(round(16.0-(14.0-log2(vel*127.0)*2.0)),0,15);
 }
 
+float DivPlatformOPLL::getGain(int ch, int vol) {
+  if (vol==0) return 0;
+  return 1.0/pow(10.0,(float)(15-vol)*3.0/20.0);
+}
+
 unsigned char* DivPlatformOPLL::getRegisterPool() {
   return regPool;
 }

src/engine/platform/opll.h

@@ -99,6 +99,7 @@ class DivPlatformOPLL: public DivDispatch {
     DivMacroInt* getChanMacroInt(int ch);
     DivDispatchOscBuffer* getOscBuffer(int chan);
     int mapVelocity(int ch, float vel);
+    float getGain(int ch, int vol);
     unsigned char* getRegisterPool();
     int getRegisterPoolSize();
     void reset();

src/engine/platform/pce.cpp

@@ -575,6 +575,11 @@ int DivPlatformPCE::mapVelocity(int ch, float vel) {
   return round(31.0*pow(vel,0.22));
 }
 
+float DivPlatformPCE::getGain(int ch, int vol) {
+  if (vol==0) return 0;
+  return 1.0/pow(10.0,(float)(31-vol)*3.0/20.0);
+}
+
 unsigned char* DivPlatformPCE::getRegisterPool() {
   return regPool;
 }

src/engine/platform/pce.h

@@ -90,6 +90,7 @@ class DivPlatformPCE: public DivDispatch {
     DivSamplePos getSamplePos(int ch);
     DivDispatchOscBuffer* getOscBuffer(int chan);
     int mapVelocity(int ch, float vel);
+    float getGain(int ch, int vol);
     unsigned char* getRegisterPool();
     int getRegisterPoolSize();
     void reset();

src/engine/platform/sms.cpp

@@ -466,6 +466,11 @@ int DivPlatformSMS::mapVelocity(int ch, float vel) {
   return round(15.0*pow(vel,0.33));
 }
 
+float DivPlatformSMS::getGain(int ch, int vol) {
+  if (vol==0) return 0;
+  return 1.0/pow(10.0,(float)(15-vol)*2.0/20.0);
+}
+
 unsigned char* DivPlatformSMS::getRegisterPool() {
   return regPool;
 }

src/engine/platform/sms.h

@@ -80,6 +80,7 @@ class DivPlatformSMS: public DivDispatch {
     unsigned short getPan(int chan);
     DivDispatchOscBuffer* getOscBuffer(int chan);
     int mapVelocity(int ch, float vel);
+    float getGain(int ch, int vol);
     unsigned char* getRegisterPool();
     int getRegisterPoolSize();
     void reset();

src/gui/gui.cpp

@@ -4680,7 +4680,7 @@ bool FurnaceGUI::loop() {
                 if (maxVol<1 || p->data[cursor.y][3]>maxVol) {
                   info=fmt::sprintf(_("Set volume: %d (%.2X, INVALID!)"),p->data[cursor.y][3],p->data[cursor.y][3]);
                 } else {
-                  float realVol=e->mapVelocity(cursor.xCoarse,(float)p->data[cursor.y][3]/(float)maxVol);
+                  float realVol=e->getGain(cursor.xCoarse,p->data[cursor.y][3]);
                   info=fmt::sprintf(_("Set volume: %d (%.2X, %d%%)"),p->data[cursor.y][3],p->data[cursor.y][3],(int)(realVol*100.0f/(float)maxVol));
                 }
                 hasInfo=true;