}
          // halfway between the representable values; do the half-whatever logic
          switch (mode) {
            case HALF_EVEN:
              // roundFloorAsDouble and roundCeilingAsDouble are neighbors, so precisely
              // one of them should have an even long representation
              return ((Double.doubleToRawLongBits(roundFloorAsDouble) & 1L) == 0)
                  ? roundFloorAsDouble