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/// An abstraction over a mutex lock.
///
/// Any type that can implement this trait can be used as a mutex for sharing a bus.
///
/// If the `std` feature is enabled, [`BusMutex`] is implemented for [`std::sync::Mutex`].
/// If the `cortexm` feature is enabled, [`BusMutex`] is implemented for [`cortex_m::interrupt::Mutex`].
///
/// If there is no feature available for your Mutex type, you have to write one yourself. It should
/// look something like this (for [`cortex_m`] as an example):
/// ```
/// # extern crate shared_bus;
/// extern crate cortex_m;
///
/// // You need a newtype because you can't implement foreign traits on
/// // foreign types.
/// struct MyMutex<T>(cortex_m::interrupt::Mutex<T>);
///
/// impl<T> shared_bus::BusMutex<T> for MyMutex<T> {
/// fn create(v: T) -> MyMutex<T> {
/// MyMutex(cortex_m::interrupt::Mutex::new(v))
/// }
///
/// fn lock<R, F: FnOnce(&T) -> R>(&self, f: F) -> R {
/// cortex_m::interrupt::free(|cs| {
/// let v = self.0.borrow(cs);
/// f(v)
/// })
/// }
/// }
///
/// type MyBusManager<L, P> = shared_bus::BusManager<MyMutex<L>, P>;
/// ```
pub trait BusMutex<T> {
/// Create a new instance of this mutex type containing the value `v`.
fn create(v: T) -> Self;
/// Lock the mutex for the duration of the closure `f`.
fn lock<R, F: FnOnce(&T) -> R>(&self, f: F) -> R;
}
#[cfg(feature = "std")]
impl<T> BusMutex<T> for ::std::sync::Mutex<T> {
fn create(v: T) -> Self {
::std::sync::Mutex::new(v)
}
fn lock<R, F: FnOnce(&T) -> R>(&self, f: F) -> R {
let v = self.lock().unwrap();
f(&v)
}
}
#[cfg(feature = "cortexm")]
impl<T> BusMutex<T> for ::cortex_m::interrupt::Mutex<T> {
fn create(v: T) -> ::cortex_m::interrupt::Mutex<T> {
::cortex_m::interrupt::Mutex::new(v)
}
fn lock<R, F: FnOnce(&T) -> R>(&self, f: F) -> R {
::cortex_m::interrupt::free(|cs| {
let v = self.borrow(cs);
f(v)
})
}
}