1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43

// Licensed under the Apache License, Version 2.0 or the MIT License.
// SPDX-License-Identifier: Apache-2.0 OR MIT
// Copyright Tock Contributors 2022.

//! Helper macros.

/// Create an object with the given capability.
///
/// ```ignore
/// use kernel::capabilities::ProcessManagementCapability;
/// use kernel;
///
/// let process_mgmt_cap = create_capability!(ProcessManagementCapability);
/// ```
///
/// This helper macro cannot be called from `#![forbid(unsafe_code)]` crates,
/// and is used by trusted code to generate a capability that it can either use
/// or pass to another module.
#[macro_export]
macro_rules! create_capability {
    ($T:ty $(,)?) => {{
        struct Cap;
        #[allow(unsafe_code)]
        unsafe impl $T for Cap {}
        Cap
    }};
}

/// Count the number of passed expressions.
/// Useful for constructing variable sized arrays in other macros.
/// Taken from the Little Book of Rust Macros
///
/// ```ignore
/// use kernel:count_expressions;
///
/// let count: usize = count_expressions!(1+2, 3+4);
/// ```
#[macro_export]
macro_rules! count_expressions {
    () => (0usize);
    ($head:expr $(,)?) => (1usize);
    ($head:expr, $($tail:expr),* $(,)?) => (1usize + count_expressions!($($tail),*));
}