Support for 10 level deep SD folder hierarchy

Marlin/cardreader.cpp

    saving = false;
    logging = false;
    autostart_atmillis=0;
+   workDirDepth = 0;
+   memset(workDirParents, 0, sizeof(workDirParents));
 
    autostart_stilltocheck=true; //the sd start is delayed, because otherwise the serial cannot answer fast enought to make contact with the hostsoftware.
    lastnr=0;
   }
   else
   {
-    workDirParentParent=workDirParent;
-    workDirParent=*parent;
-    
+    if (workDirDepth < MAX_DIR_DEPTH) {
+      for (int d = ++workDirDepth; d--;)
+        workDirParents[d+1] = workDirParents[d];
+      workDirParents[0]=*parent;
+    }
     workDir=newfile;
   }
 }
 
 void CardReader::updir()
 {
-  if(!workDir.isRoot())
+  if(workDirDepth > 0)
   {
-    workDir=workDirParent;
-    workDirParent=workDirParentParent;
+    --workDirDepth;
+    workDir = workDirParents[0];
+    int d;
+    for (int d = 0; d < workDirDepth; d++)
+      workDirParents[d] = workDirParents[d+1];
   }
 }
 

Marlin/cardreader.h

 
 #ifdef SDSUPPORT
 
+#define MAX_DIR_DEPTH 10
+
 #include "SdFile.h"
 enum LsAction {LS_SerialPrint,LS_Count,LS_GetFilename};
 class CardReader
   bool filenameIsDir;
   int lastnr; //last number of the autostart;
 private:
-  SdFile root,*curDir,workDir,workDirParent,workDirParentParent;
+  SdFile root,*curDir,workDir,workDirParents[MAX_DIR_DEPTH];
+  uint16_t workDirDepth;
   Sd2Card card;
   SdVolume volume;
   SdFile file;