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|
/// Macro for sending a formatted string through an ITM channel
#[macro_export]
macro_rules! iprint {
($channel:expr, $s:expr) => {
$crate::itm::write_str($channel, $s);
};
($channel:expr, $($arg:tt)*) => {
$crate::itm::write_fmt($channel, format_args!($($arg)*));
};
}
/// Macro for sending a formatted string through an ITM channel, with a newline.
#[macro_export]
macro_rules! iprintln {
($channel:expr) => {
$crate::itm::write_str($channel, "\n");
};
($channel:expr, $fmt:expr) => {
$crate::itm::write_str($channel, concat!($fmt, "\n"));
};
($channel:expr, $fmt:expr, $($arg:tt)*) => {
$crate::itm::write_fmt($channel, format_args!(concat!($fmt, "\n"), $($arg)*));
};
}
/// Macro to create a mutable reference to a statically allocated value
///
/// This macro returns a value with type `Option<&'static mut $ty>`. `Some($expr)` will be returned
/// the first time the macro is executed; further calls will return `None`. To avoid `unwrap`ping a
/// `None` variant the caller must ensure that the macro is called from a function that's executed
/// at most once in the whole lifetime of the program.
///
/// # Notes
/// This macro is unsound on multi core systems.
///
/// For debuggability, you can set an explicit name for a singleton. This name only shows up the
/// the debugger and is not referencable from other code. See example below.
///
/// # Example
///
/// ``` no_run
/// use cortex_m::singleton;
///
/// fn main() {
/// // OK if `main` is executed only once
/// let x: &'static mut bool = singleton!(: bool = false).unwrap();
///
/// let y = alias();
/// // BAD this second call to `alias` will definitively `panic!`
/// let y_alias = alias();
/// }
///
/// fn alias() -> &'static mut bool {
/// singleton!(: bool = false).unwrap()
/// }
///
/// fn singleton_with_name() {
/// // A name only for debugging purposes
/// singleton!(FOO_BUFFER: [u8; 1024] = [0u8; 1024]);
/// }
/// ```
#[macro_export]
macro_rules! singleton {
($name:ident: $ty:ty = $expr:expr) => {
$crate::interrupt::free(|_| {
// this is a tuple of a MaybeUninit and a bool because using an Option here is
// problematic: Due to niche-optimization, an Option could end up producing a non-zero
// initializer value which would move the entire static from `.bss` into `.data`...
static mut $name: (::core::mem::MaybeUninit<$ty>, bool) =
(::core::mem::MaybeUninit::uninit(), false);
#[allow(unsafe_code)]
let used = unsafe { $name.1 };
if used {
None
} else {
let expr = $expr;
#[allow(unsafe_code)]
unsafe {
$name.1 = true;
$name.0 = ::core::mem::MaybeUninit::new(expr);
Some(&mut *$name.0.as_mut_ptr())
}
}
})
};
(: $ty:ty = $expr:expr) => {
$crate::singleton!(VAR: $ty = $expr)
};
}
/// ``` compile_fail
/// use cortex_m::singleton;
///
/// fn foo() {
/// // check that the call to `uninitialized` requires unsafe
/// singleton!(: u8 = std::mem::uninitialized());
/// }
/// ```
#[allow(dead_code)]
const CFAIL: () = ();
/// ```
/// #![deny(unsafe_code)]
/// use cortex_m::singleton;
///
/// fn foo() {
/// // check that calls to `singleton!` don't trip the `unsafe_code` lint
/// singleton!(: u8 = 0);
/// }
/// ```
#[allow(dead_code)]
const CPASS: () = ();
|
