int oldValue = VM_Interface.readAvailableBitsWord(VM_Magic.objectAsAddress(ref)); int newValue = (oldValue & ~GC_BITS_MASK) | Plan.getInitialHeaderValue(size);
VM_Word oldValue = VM_Interface.readAvailableBitsWord(VM_Magic.objectAsAddress(ref)); VM_Word newValue = oldValue.and(GC_BITS_MASK.not()).or(Plan.getInitialHeaderValue(size));
  public static void initializeLOSHeader(VM_Address ref, Object[] tib, int size,                                         boolean isScalar)    throws VM_PragmaUninterruptible, VM_PragmaInline {    int oldValue = VM_Interface.readAvailableBitsWord(VM_Magic.objectAsAddress(ref));    int newValue = (oldValue & ~GC_BITS_MASK) | Plan.getInitialHeaderValue(size);    VM_Interface.writeAvailableBitsWord(VM_Magic.objectAsAddress(ref), newValue);  }