public static void writeMarkBit(VM_Address ref, int value)
public static void writeMarkBit(VM_Address ref, VM_Word value)
  public static void writeMarkBit(VM_Address ref, int value)    throws VM_PragmaUninterruptible, VM_PragmaInline {    int oldValue = VM_Interface.readAvailableBitsWord(ref);    int newValue = (oldValue & ~MARK_BIT_MASK) | value;    VM_Interface.writeAvailableBitsWord(ref,newValue);  }