fix crash when changing chip

it was somehow possible to exceed the channel limit...

src/engine/engine.cpp

@@ -1003,7 +1003,16 @@ void DivEngine::delUnusedSamples() {
   BUSY_END;
 }
 
-void DivEngine::changeSystem(int index, DivSystem which, bool preserveOrder) {
+bool DivEngine::changeSystem(int index, DivSystem which, bool preserveOrder) {
+  if (index<0 || index>=song.systemLen) {
+    lastError="invalid index";
+    return false;
+  }
+  if (chans-getChannelCount(song.system[index])+getChannelCount(which)>DIV_MAX_CHANS) {
+    lastError=fmt::sprintf("max number of total channels is %d",DIV_MAX_CHANS);
+    return false;
+  }
+
   int chanCount=chans;
   quitDispatch();
   BUSY_BEGIN;
@@ -1045,6 +1054,8 @@ void DivEngine::changeSystem(int index, DivSystem which, bool preserveOrder) {
   renderSamples();
   reset();
   BUSY_END;
+
+  return true;
 }
 
 bool DivEngine::addSystem(DivSystem which) {
@@ -1097,6 +1108,65 @@ bool DivEngine::addSystem(DivSystem which) {
   return true;
 }
 
+bool DivEngine::duplicateSystem(int index, bool pat, bool end) {
+  if (index<0 || index>=song.systemLen) {
+    lastError="invalid index";
+    return false;
+  }
+  if (song.systemLen>DIV_MAX_CHIPS) {
+    lastError=fmt::sprintf("max number of systems is %d",DIV_MAX_CHIPS);
+    return false;
+  }
+  if (chans+getChannelCount(song.system[index])>DIV_MAX_CHANS) {
+    lastError=fmt::sprintf("max number of total channels is %d",DIV_MAX_CHANS);
+    return false;
+  }
+  quitDispatch();
+  BUSY_BEGIN;
+  saveLock.lock();
+  song.system[song.systemLen]=song.system[index];
+  song.systemVol[song.systemLen]=song.systemVol[index];
+  song.systemPan[song.systemLen]=song.systemPan[index];
+  song.systemPanFR[song.systemLen]=song.systemPanFR[index];
+  song.systemFlags[song.systemLen++]=song.systemFlags[index];
+  recalcChans();
+  saveLock.unlock();
+  BUSY_END;
+  initDispatch();
+  BUSY_BEGIN;
+  saveLock.lock();
+  if (song.patchbayAuto) {
+    autoPatchbay();
+  } else {
+    int i=song.systemLen-1;
+    if (disCont[i].dispatch!=NULL) {
+      unsigned int outs=disCont[i].dispatch->getOutputCount();
+      if (outs>16) outs=16;
+      if (outs<2) {
+        song.patchbay.reserve(DIV_MAX_OUTPUTS);
+        for (unsigned int j=0; j<DIV_MAX_OUTPUTS; j++) {
+          song.patchbay.push_back((i<<20)|j);
+        }
+      } else {
+        if (outs>0) song.patchbay.reserve(outs);
+        for (unsigned int j=0; j<outs; j++) {
+          song.patchbay.push_back((i<<20)|(j<<16)|j);
+        }
+      }
+    }
+  }
+
+  // duplicate patterns
+  if (pat) {
+    
+  }
+  saveLock.unlock();
+  renderSamples();
+  reset();
+  BUSY_END;
+  return true;
+}
+
 // TODO: maybe issue with subsongs?
 bool DivEngine::removeSystem(int index, bool preserveOrder) {
   if (song.systemLen<=1) {

src/engine/engine.h

@@ -1155,11 +1155,14 @@ class DivEngine {
     void delUnusedSamples();
 
     // change system
-    void changeSystem(int index, DivSystem which, bool preserveOrder=true);
+    bool changeSystem(int index, DivSystem which, bool preserveOrder=true);
 
     // add system
     bool addSystem(DivSystem which);
 
+    // duplicate system
+    bool duplicateSystem(int index, bool pat=true, bool end=false);
+
     // remove system
     bool removeSystem(int index, bool preserveOrder=true);
 

src/gui/gui.cpp

@@ -4284,12 +4284,15 @@ bool FurnaceGUI::loop() {
               if (ImGui::BeginMenu(fmt::sprintf("%d. %s##_SYSC%d",i+1,getSystemName(e->song.system[i]),i).c_str())) {
                 DivSystem picked=systemPicker();
                 if (picked!=DIV_SYSTEM_NULL) {
-                  e->changeSystem(i,picked,preserveChanPos);
-                  MARK_MODIFIED;
-                  if (e->song.autoSystem) {
-                    autoDetectSystem();
+                  if (e->changeSystem(i,picked,preserveChanPos)) {
+                    MARK_MODIFIED;
+                    if (e->song.autoSystem) {
+                      autoDetectSystem();
+                    }
+                    updateWindowTitle();
+                  } else {
+                    showError("cannot change chip! ("+e->getLastError()+")");
                   }
-                  updateWindowTitle();
                   ImGui::CloseCurrentPopup();
                 }
                 ImGui::EndMenu();

src/gui/sysManager.cpp

@@ -83,16 +83,27 @@ void FurnaceGUI::drawSysManager() {
           ImGui::TreePop();
         }
         ImGui::TableNextColumn();
+        if (ImGui::Button("Clone##SysDup")) {
+          if (!e->duplicateSystem(i)) {
+            showError("cannot clone chip! ("+e->getLastError()+")");
+          } else {
+            MARK_MODIFIED;
+          }
+        }
+        ImGui::SameLine();
         ImGui::Button("Change##SysChange");
         if (ImGui::BeginPopupContextItem("SysPickerC",ImGuiPopupFlags_MouseButtonLeft)) {
           DivSystem picked=systemPicker();
           if (picked!=DIV_SYSTEM_NULL) {
-            e->changeSystem(i,picked,preserveChanPos);
-            MARK_MODIFIED;
-            if (e->song.autoSystem) {
-              autoDetectSystem();
+            if (e->changeSystem(i,picked,preserveChanPos)) {
+              MARK_MODIFIED;
+              if (e->song.autoSystem) {
+                autoDetectSystem();
+              }
+              updateWindowTitle();
+            } else {
+              showError("cannot change chip! ("+e->getLastError()+")");
             }
-            updateWindowTitle();
             ImGui::CloseCurrentPopup();
           }
           ImGui::EndPopup();