prepare for better ins del safety

src/engine/dispatch.h

@@ -196,6 +196,11 @@ class DivDispatch {
      */
     void setSkipRegisterWrites(bool value);
 
+    /**
+     * notify deletion of an instrument.
+     */
+    virtual void notifyInsDeletion(void* ins);
+
     /**
      * force-retrigger instruments.
      */

src/engine/engine.cpp

@@ -2706,6 +2706,9 @@ int DivEngine::addInstrument(int refChan) {
 void DivEngine::delInstrument(int index) {
   isBusy.lock();
   if (index>=0 && index<(int)song.ins.size()) {
+    for (int i=0; i<song.systemLen; i++) {
+      disCont[i].dispatch->notifyInsDeletion(song.ins[index]);
+    }
     delete song.ins[index];
     song.ins.erase(song.ins.begin()+index);
     song.insLen=song.ins.size();

src/engine/platform/abstract.cpp

@@ -46,6 +46,10 @@ void DivDispatch::setSkipRegisterWrites(bool value) {
   skipRegisterWrites=value;
 }
 
+void DivDispatch::notifyInsDeletion(void* ins) {
+
+}
+
 void DivDispatch::forceIns() {
   
 }