Macro io_project 

macro_rules! io_project {
    ($io:expr, try: $ioloc:expr) => { ... };
    ($io:expr, build: $ioloc:expr) => { ... };
    ($io:expr, $($proj:tt)*) => { ... };
}

Project an I/O type to a subview of it.

The syntax is of form io_project!(io, proj) where io is an expression to a type that implements Io and proj is a projection specification.

io_project! can also project to a subview of registers defined with register! macro. Register projection has syntax io_project!(io, try: REGISTER) for fallible projection and io_project!(io, build: REGISTER) for infallible projection.

Examples

use kernel::io::{
    io_project,
    register,
    Mmio,
};
#[repr(C)]
struct MyStruct { field: u32, }

register! {
    base: MyStruct;
    FIELD(u32) @ 0 {
        31:0 val;
    }
}

// let mmio: Mmio<[MyStruct]>;
let field: Mmio<'_, u32> = io_project!(mmio, [try: 1].field);
let whole: Mmio<'_, MyStruct> = io_project!(mmio, [try: 2]);
let nested: Mmio<'_, u32> = io_project!(whole, .field);
let reg: Mmio<'_, FIELD> = io_project!(whole, build: FIELD);