Macro on_disk_struct_helper 

macro_rules! on_disk_struct_helper {
    (@check_layout no_gaps, $field_offset:literal, $actual_offset:expr) => { ... };
    (@check_layout allow_gaps, $field_offset:literal, $actual_offset:expr) => { ... };
    (@load NE, $type:ty, $slice:expr) => { ... };
    (@load LE, $type:ty, $slice:expr) => { ... };
    (@load BE, $type:ty, $slice:expr) => { ... };
    (@store NE, $value:expr, $slice:expr) => { ... };
    (@store LE, $value:expr, $slice:expr) => { ... };
    (@store BE, $value:expr, $slice:expr) => { ... };
}

Helper macro for on_disk_struct.

Various functionalities, selected by the first parameter.