Function esp_idf_bindgen::rtc_clk_cal_ratio

pub unsafe extern "C" fn rtc_clk_cal_ratio(
    cal_clk: rtc_cal_sel_t, 
    slow_clk_cycles: u32
) -> u32

@brief Measure ratio between XTAL frequency and RTC slow clock frequency @param cal_clk slow clock to be measured @param slow_clk_cycles number of slow clock cycles to average @return average ratio between XTAL frequency and slow clock frequency, Q13.19 fixed point format, or 0 if calibration has timed out.