Function ftofix

* \fn fixed ftofix (double x) * \brief Converts a float point value to a fixed point value. * * This function converts the specified float point value \a x to * a fixed point value. * * \note The float point should be ranged from -32767.0 to 32767.0. * If it runs out of the range, this function sets \a errno to \a ERANGE. * * \sa fixtof */