private long diode ( long offset , long length ) { int lb = ( int ) ( 64 - offset ) ; int rb = ( int ) ( 64 - ( offset + length ) ) ; return ( - 1L << lb ) ^ ( - 1L << rb ) ; }
a diode is a long value whose left and right margin are ZERO while middle bits are ONE in binary string layout . it looks like a diode in shape .