Function phydat_to_json

pub unsafe extern "C" fn phydat_to_json(
    data: *const phydat_t,
    dim: size_t,
    buf: *mut c_char,
) -> size_t

@brief Convert the given phydat_t structure into a JSON string

The output string written to @p buf will be \0 terminated. You must make sure, that the given @p buf is large enough to hold the resulting string. You can call the function with @p buf := NULL to simply calculate the size of the JSON string without writing anything.

The formatted JSON string will have the following format:

// case (dim == 1):
{
  "d": 21.45,
  "u": "°C"
}

// case (dim > 1), dim := 3 in this case:
{
  "d": [1.02, 0.23, -0.81],
  "u": "g"
}

The data will be encoded as fixed point number based on the given scale factor.

For encoding the unit, this function uses the extended phydat_unit_write() function to also print units for non-SI types, e.g. it will produce ..."u":"date"} for @ref UNIT_DATE or ..."u":"none"} for @ref UNIT_NONE.

@param[in] data data to encode @param[in] dim dimensions used in @p data, MUST be > 0 and <= PHYDAT_DIM @param[out] buf target buffer for the JSON string, or NULL

@pre @p dim > 0 @pre @p dim <= PHYDAT_DIM

@return number of bytes (potentially) written to @p buf, including \0 terminator