code: public void setRootDirEntryCount(int v) throws IllegalArgumentException {
          if (v < 0) throw new IllegalArgumentException();
          if (v == getRootDirEntryCount()) return;
          
          set16(ROOT_DIR_ENTRIES_OFFSET, v);
      }
docs: Sets the number of entries in the root directory
  
  @param v the new number of entries in the root directory
  @throws IllegalArgumentException for negative values