Function gfrr_c 

pub unsafe extern "C" fn gfrr_c(
    target: *mut u8,
    abcorr: *mut u8,
    obsrvr: *mut u8,
    relate: *mut u8,
    refval: f64,
    adjust: f64,
    step: f64,
    nintvls: i32,
    cnfine: *mut _SpiceCell,
    result: *mut _SpiceCell,
)