split file ops code

CMakeLists.txt

@@ -267,6 +267,7 @@ src/engine/safeReader.cpp
 src/engine/safeWriter.cpp
 src/engine/dispatchContainer.cpp
 src/engine/engine.cpp
+src/engine/fileOps.cpp
 src/engine/instrument.cpp
 src/engine/macroInt.cpp
 src/engine/pattern.cpp

src/engine/engine.h

@@ -218,6 +218,8 @@ class DivEngine {
 
   private: int* jediTable;
 
+  DivSystem systemFromFile(unsigned char val);
+  unsigned char systemToFile(DivSystem val);
   int dispatchCmd(DivCommand c);
   void processRow(int i, bool afterDelay);
   void nextOrder();