Macro tock_registers::register_fields

macro_rules! register_fields {
    (@root $(#[$attr_struct:meta])* $vis_struct:vis $name:ident $(<$life:lifetime>)? { $($input:tt)* } ) => { ... };
    (@munch
        (
            $(#[$attr_end:meta])*
            ($offset:expr => @END),
        )
        -> {$vis_struct:vis struct $(#[$attr_struct:meta])* $name:ident $(<$life:lifetime>)? $(
                $(#[$attr:meta])*
                ($vis:vis $id:ident: $ty:ty)
            )*}
    ) => { ... };
    (@munch
        (
            $(#[$attr:meta])*
            ($offset_start:expr => $vis:vis $field:ident: $ty:ty),
            $($after:tt)*
        )
        -> {$($output:tt)*}
    ) => { ... };
    (@munch
        (
            $(#[$attr:meta])*
            ($offset_start:expr => $padding:ident),
            $(#[$attr_next:meta])*
            ($offset_end:expr => $($next:tt)*),
            $($after:tt)*
        )
        -> {$($output:tt)*}
    ) => { ... };
}