macro_rules! read_ty { ($func_name:ident, $ty:ty, 1) => { ... }; ($func_name:ident, $ty:ty, 2) => { ... }; ($func_name:ident, $ty:ty, 4) => { ... }; ($func_name:ident, $ty:ty, 8) => { ... }; ($func_name:ident, $ty:ty, 16) => { ... }; }