int logFloor = x.bitLength() - 1;
    switch (mode) {
      case UNNECESSARY:
        checkRoundingUnnecessary(isPowerOfTwo(x)); // fall through
      case DOWN:
      case FLOOR:
        return logFloor;

      case UP:
      case CEILING:
        return isPowerOfTwo(x) ? logFloor : logFloor + 1;

      case HALF_DOWN:
      case HALF_UP:
      case HALF_EVEN: