Macro tock_registers::test_fields

source ·

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

Expand description

Statically validate the size and offsets of the fields defined within the register struct through the register_structs!() macro.

This macro expands to an expression which contains static assertions about various parameters of the individual fields in the register struct definition. It will test for:

Proper start offset of padding fields. It will fail in cases such as

# #[macro_use]
# extern crate tock_registers;
# use tock_registers::register_structs;
# use tock_registers::registers::ReadWrite;
register_structs! {
    UartRegisters {
        (0x04 => _reserved),
        (0x08 => foo: ReadWrite<u32>),
        (0x0C => @END),
    }
}
# // This is required for rustdoc to not place this code snipped into an
# // fn main() {...} function.
# fn main() { }

In this example, the start offset of _reserved should have been 0x00 instead of 0x04.

Correct start offset and end offset (start offset of next field) in actual fields. It will fail in cases such as

# #[macro_use]
# extern crate tock_registers;
# use tock_registers::register_structs;
# use tock_registers::registers::ReadWrite;
register_structs! {
    UartRegisters {
        (0x00 => foo: ReadWrite<u32>),
        (0x05 => bar: ReadWrite<u32>),
        (0x08 => @END),
    }
}
# // This is required for rustdoc to not place this code snipped into an
# // fn main() {...} function.
# fn main() { }

In this example, the start offset of bar and thus the end offset of foo should have been 0x04 instead of 0x05.

Invalid alignment of fields.

That the end marker matches the actual generated struct size. This will fail in cases such as

# #[macro_use]
# extern crate tock_registers;
# use tock_registers::register_structs;
# use tock_registers::registers::ReadWrite;
register_structs! {
    UartRegisters {
        (0x00 => foo: ReadWrite<u32>),
        (0x04 => bar: ReadWrite<u32>),
        (0x10 => @END),
    }
}
# // This is required for rustdoc to not place this code snipped into an
# // fn main() {...} function.
# fn main() { }