pub unsafe extern "C" fn fftwf_plan_guru64_r2r(
rank: c_int,
dims: *const fftwf_iodim64,
howmany_rank: c_int,
howmany_dims: *const fftwf_iodim64,
in_: *mut f32,
out: *mut f32,
kind: *const fftwf_r2r_kind,
flags: c_uint,
) -> fftwf_plan