better global pitch effect

still work in progress

src/engine/platform/nes.cpp

@@ -121,7 +121,7 @@ void DivPlatformNES::tick() {
       if (i==3) { // noise
         chan[i].freq=noiseTable[chan[i].baseFreq];
       } else {
-        chan[i].freq=(chan[i].baseFreq*(ONE_SEMITONE-chan[i].pitch))/ONE_SEMITONE;
+        chan[i].freq=(chan[i].baseFreq*pow(2,(double)-chan[i].pitch/(12.0*128.0)));
         if (chan[i].freq>2047) chan[i].freq=2047;
       }
       if (chan[i].keyOn) {

src/engine/playback.cpp

@@ -522,10 +522,14 @@ void DivEngine::processRow(int i, bool afterDelay) {
         extValuePresent=true;
         break;
       case 0xef: // global pitch
-        globalPitch+=(signed char)(effectVal-0x80)*120;
+        for (int i=0; i<chans; i++) {
+          chan[i].pitch-=globalPitch;
+        }
+        globalPitch+=(signed char)(effectVal-0x80)*(120-globalPitch/28);
         printf("setting global pitch to %d\n",globalPitch);
         for (int i=0; i<chans; i++) {
           chan[i].pitch+=globalPitch;
+          dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(((chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
         }
         break;
     }

src/gui/gui.cpp

@@ -1985,7 +1985,6 @@ void FurnaceGUI::doUndo() {
         updateScroll(cursor.y);
         e->setOrder(us.order);
       }
-
       break;
   }