nucleo-f042k6 0.5.0

use core::{
    cell::RefCell,
    ops::{Deref, DerefMut},
};

use bare_metal::{CriticalSection, Mutex};

pub struct Shared<T> {
    inner: Mutex<RefCell<Option<T>>>,
}

impl <T> Shared<T> {
    /// Creates a new shared value
    #[cfg(feature = "const-fn")]
    pub const fn new() -> Self {
        Shared {
            inner: Mutex::new(RefCell::new(None)),
        }
    }

    /// Creates a new shared value
    #[cfg(not(feature = "const-fn"))]
    pub fn new() -> Self {
        Shared {
            inner: Mutex::new(RefCell::new(None)),
        }
    }

    pub fn load(&mut self, cs: &CriticalSection, value: T) -> Option<T> {
        self.inner.borrow(cs).replace(Some(value))
    }

    pub fn get<'a>(&'a self, cs: &'a CriticalSection) -> Option<core::cell::Ref<'a, T>> {
        match self.inner.borrow(cs).try_borrow().ok() {
            Some(inner) => match inner.deref() {
                Some(_) => Some(core::cell::Ref::map(inner, |v| v.as_ref().unwrap())),
                None => None,
            }
            None => None,
        }
    }

    pub fn get_mut<'a>(&'a self, cs: &'a CriticalSection) -> Option<core::cell::RefMut<'a, T>> {
        match self.inner.borrow(cs).try_borrow_mut().ok() {
            Some(mut inner) => match inner.deref_mut() {
                Some(_) => Some(core::cell::RefMut::map(inner, |v| v.as_mut().unwrap())),
                None => None,
            }
            None => None,
        }
    }
}