Function alsa_sys::snd_ctl_convert_to_dB

pub unsafe extern "C" fn snd_ctl_convert_to_dB(
    ctl: *mut snd_ctl_t, 
    id: *const snd_ctl_elem_id_t, 
    volume: c_long, 
    db_gain: *mut c_long
) -> c_int