Attribute Macro bitsize 

#[bitsize]

Defines the bitsize of a struct or an enum.

e.g. #[bitsize(4)] represents the item as a u4, which is UInt<u8, 4> underneath. The size of structs is currently limited to 128 bits. The size of enums is limited to 64 bits. Please open an issue if you have a usecase for bigger bitfields.

After the size, structs may take extra options:

• hide_value: place the generated struct in a private module so the raw value field cannot be read or written. To write the whole value, use From/TryFrom instead, which is more type-safe. Relative visibility (pub(super), pub(self), inherited) is shifted one super so it works like you wrote it.
• new = <vis>: visibility of new (private by default, like other Rust items). Examples: new = pub, new = pub(crate).

#[bitsize(8, hide_value, new = pub(crate))]
struct Register { ... }