Function esp_rom_cvt 

pub unsafe extern "C" fn esp_rom_cvt(
    val: c_ulonglong,
    radix: c_long,
    pad: c_int,
    digits: *const c_char,
    buf: *mut c_char,
) -> c_int

@brief Convert an unsigned integer value to a string representation in the specified radix.

This function converts the given unsigned integer value to a string representation in the specified radix. The resulting string is stored in the provided character buffer buf.

@param[in] val The unsigned integer value to be converted. @param[in] radix The base of the numeral system to be used for the conversion. It determines the number of unique digits in the numeral system (e.g., 2 for binary, 10 for decimal, 16 for hexadecimal). @param[in] pad The optional padding width (0 - unused) for the resulting string. It adds zero-padding. (val=123, pad=6 -> result=000123). @param[in] digits Pointer to a character array representing the digits of the numeral system. The array must contain characters in the order of increasing values, corresponding to the digits of the radix. For example, “0123456789ABCDEF” or hexadecimal. @param[out] buf Pointer to the character buffer where the resulting string will be stored. The buffer must have enough space to accommodate the entire converted string, including the null-terminator.

@return The length of the resulting string (excluding the null-terminator).

@note The buffer buf must have sufficient space to hold the entire converted string, including the null-terminator. The caller is responsible for ensuring the buffer’s size is large enough to prevent buffer overflow. @note The provided digits array must have enough elements to cover the entire radix used for conversion. Otherwise, undefined behavior may occur.