Function alsa_sys::snd_ctl_convert_from_dB

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