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https://github.com/rtic-rs/rtic.git
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using bool
This commit is contained in:
pln
parent
a568afaf27
commit
8e0569c396
1 changed files with 308 additions and 30 deletions
338
src/lib.rs
338
src/lib.rs
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@ -59,36 +59,6 @@ impl<T, C> Resource<T, C> {
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}
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}
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#[derive(Copy, Clone)]
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enum State {
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Free,
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// Locked,
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LockedMut,
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}
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/// A resource
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pub struct Res<T, CEILING> {
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_ceiling: PhantomData<CEILING>,
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_state: Cell<State>,
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//_state: State,
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data: UnsafeCell<T>,
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}
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impl<T, C> Res<T, C> {
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/// Creates a new resource with ceiling `C`
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pub const fn new(data: T) -> Self
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where
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C: Ceiling,
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{
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Res {
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_ceiling: PhantomData,
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_state: Cell::new(State::Free),
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// _state: State::Free,
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data: UnsafeCell::new(data),
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}
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}
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}
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impl<T, CEILING> Resource<T, C<CEILING>> {
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/// Borrows the resource for the duration of another resource's critical
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/// section
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@ -221,6 +191,313 @@ where
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{
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}
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// re-implementation of the original claim API
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/// A resource
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pub struct Res<T, CEILING> {
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_ceiling: PhantomData<CEILING>,
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_state: Cell<bool>,
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data: UnsafeCell<T>,
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}
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impl<T, C> Res<T, C> {
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/// Creates a new resource with ceiling `C`
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pub const fn new(data: T) -> Self
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where
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C: Ceiling,
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{
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Res {
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_ceiling: PhantomData,
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_state: Cell::new(true),
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// _state: State::Free,
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data: UnsafeCell::new(data),
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}
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}
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}
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impl<T, CEILING> Res<T, C<CEILING>> {
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/// Locks the resource for the duration of the critical section `f`
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///
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/// For the duration of the critical section, tasks whose priority level is
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/// smaller than or equal to the resource `CEILING` will be prevented from
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/// preempting the current task.
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///
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/// claim takes three args of type R, PRIOTASK, CURRCEIL, F
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/// R is the Resource to lock (self)
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/// PRIOTASK is the priority of the task (context) calling claim
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/// CURRCEIL is the current system ceiling
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///
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/// F is the type of the closure, hande &T and &C
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/// &T is a read only reference to the data
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/// &C is the new system ceiling
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///
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/// Usage example: a task at prio P1, claiming R1 and R2.
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/// fn j(_task: Exti0, p: P1) {
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/// R1.claim_mut(
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/// &p, &p.as_ceiling(), |a, c| {
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/// R2.claim_mut(
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/// &p, &c, |b, _| {
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/// b.y = a[0]; // b is mutable
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/// a[1] = b.y; // a is mutable
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/// }
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/// );
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/// a[2] = 0; // a is mutable
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/// }
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/// );
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/// }
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/// The implementation satisfies the following
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/// 1. Race free access to the resources under the Stack Resource Policy (SRP)
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/// System ceiling SC, is implemented by the NVIC as MAX(TASKPRI, BASEPRPI)
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/// Hence in case TASKPRI = SC, the BASEPRI register does not need to be updated
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/// as checked by c2 > c1 (this an optimization)
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///
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/// 2. Static (compile time verification) that SC >= TASKPRI
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/// This is achieved by the type bound CEILING: GreaterThanOrEqual<TASKPRI>
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/// This gives ensurence that no task access a resoure with lower ceiling value than the task
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/// and hence satisfies the soundness rule of SRP
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///
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/// 3. The system ceileng for the closure CS = MAX(CURRCEIL, R)
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/// This is achieved by &C<<CEILING as Max<CURRCEIL>>::Output>
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/// where Max operates on R and CEILING
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///
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/// 4. Rust aliasing rules are ensured as run-time check raises a panic if resourse state is locked
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/// This resembles the RefCell implementation, but the implementation is more strict as multiple
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/// readers are disallowed. Essentially this forbids re-locking
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///
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/// Usage example failing: a task at prio P1, claiming R1 and R1.
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/// fn j(_task: Exti0, p: P1) {
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/// R1.claim_mut(
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/// &p, &p.as_ceiling(), |a1, c| {
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/// R1.claim_mut( <-- at this point a panic will occur
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/// &p, &c, |a2, _| {
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/// }
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/// );
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/// a1[2] = 0; // a is mutable
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/// }
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/// );
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/// }
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///
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/// 5. The ceiling of the closure cannot be leaked
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///
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/// fn jres_opt_leak(_task: Exti0, p: P1) {
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/// R1.claim_mut(
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/// &p, &p.as_ceiling(), |a, c| {
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/// let leak_c = R2.claim_mut(&p, &c, |b, c| c); <-- trying to leak c as a return value
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///
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/// R5.claim_mut(&p, leak_c, |b, c| {}); <-- trying to use a leaked system ceilng
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///
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/// a[2] = 0;
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/// }
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/// );
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/// }
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///
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/// The compiler will reject leakage due to the lifetime, (c in a closure is a &C, so it cannot be returned)
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/// A leakage would indeed be fatal as claim would hand out an unprotected R
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#[cfg(not(thumbv6m))]
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pub fn claim_mut<R, TASKPRI, CURRCEIL, F>(
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&'static self,
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_prio: &P<TASKPRI>,
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_curr_ceil: &C<CURRCEIL>,
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f: F,
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) -> R
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where
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F: FnOnce(&mut T, &C<<CEILING as Max<CURRCEIL>>::Output>) -> R,
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TASKPRI: Unsigned,
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CURRCEIL: Unsigned,
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CEILING: GreaterThanOrEqual<TASKPRI> + Max<CURRCEIL> + Level + Unsigned,
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{
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if self._state.get() {
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unsafe {
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let curr_ceil = <CURRCEIL>::to_u8();
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let new_ceil = <CEILING>::to_u8();
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if new_ceil > curr_ceil {
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let old_basepri = basepri::read();
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basepri_max::write(<CEILING>::hw());
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barrier!();
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self._state.set(false);
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barrier!();
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let ret =
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f(&mut *self.data.get(), &C { _marker: PhantomData });
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barrier!();
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self._state.set(true);
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barrier!();
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basepri::write(old_basepri);
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ret
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} else {
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self._state.set(false);
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barrier!();
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let ret =
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f(&mut *self.data.get(), &C { _marker: PhantomData });
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barrier!();
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self._state.set(true);
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ret
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}
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}
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} else {
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panic!("Resource already locked)")
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}
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}
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/// Read only claim, see claim_mut above
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#[cfg(not(thumbv6m))]
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pub fn claim<R, TASKPRI, CURRCEIL, F>(
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&'static self,
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_prio: &P<TASKPRI>,
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_curr_ceil: &C<CURRCEIL>,
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f: F,
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) -> R
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where
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F: FnOnce(&T, &C<<CEILING as Max<CURRCEIL>>::Output>) -> R,
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TASKPRI: Unsigned,
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CURRCEIL: Unsigned,
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CEILING: GreaterThanOrEqual<TASKPRI> + Max<CURRCEIL> + Level + Unsigned,
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{
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if self._state.get() {
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unsafe {
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let curr_ceil = <CURRCEIL>::to_u8();
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let new_ceil = <CEILING>::to_u8();
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if new_ceil > curr_ceil {
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let old_basepri = basepri::read();
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basepri_max::write(<CEILING>::hw());
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barrier!();
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self._state.set(false);
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barrier!();
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let ret = f(&*self.data.get(), &C { _marker: PhantomData });
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barrier!();
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self._state.set(true);
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barrier!();
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basepri::write(old_basepri);
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ret
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} else {
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self._state.set(false);
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barrier!();
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let ret = f(&*self.data.get(), &C { _marker: PhantomData });
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barrier!();
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self._state.set(true);
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ret
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}
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}
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} else {
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panic!("Resource already locked)")
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}
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}
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/// Unsafe version of claim_mut
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#[cfg(not(thumbv6m))]
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pub unsafe fn claim_mut_unsafe<R, TASKPRI, CURRCEIL, F>(
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&'static self,
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_prio: &P<TASKPRI>,
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_curr_ceil: &C<CURRCEIL>,
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f: F,
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) -> R
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where
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F: FnOnce(&mut T, &C<<CEILING as Max<CURRCEIL>>::Output>) -> R,
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TASKPRI: Unsigned,
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CURRCEIL: Unsigned,
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CEILING: GreaterThanOrEqual<TASKPRI> + Max<CURRCEIL> + Level + Unsigned,
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{
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let curr_ceil = <CURRCEIL>::to_u8();
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let new_ceil = <CEILING>::to_u8();
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if new_ceil > curr_ceil {
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let old_basepri = basepri::read();
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basepri_max::write(<CEILING>::hw());
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barrier!();
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let ret = f(&mut *self.data.get(), &C { _marker: PhantomData });
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barrier!();
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basepri::write(old_basepri);
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ret
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} else {
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let ret = f(&mut *self.data.get(), &C { _marker: PhantomData });
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ret
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}
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}
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// / Locks the resource for the duration of the critical section `f`
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// /
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// / For the duration of the critical section, tasks whose priority level is
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// / smaller than or equal to the resource `CEILING` will be prevented from
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// / preempting the current task.
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// /
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// / Within this critical section, resources with ceiling equal to or smaller
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// / than `CEILING` can be borrowed at zero cost. See
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// / [Resource.borrow](struct.Resource.html#method.borrow).
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// #[cfg(not(thumbv6m))]
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// pub fn claim_mut<R, PRIOTASK, CURRCEIL, F>(
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// &'static self,
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// _prio: &P<PRIOTASK>,
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// _curr_ceil: &C<CURRCEIL>,
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// f: F,
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// ) -> R
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// where
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// F: FnOnce(&mut T, &C<<CEILING as Max<CURRCEIL>>::Output>) -> R,
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// PRIOTASK: Unsigned,
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// CURRCEIL: Unsigned,
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// CEILING: GreaterThanOrEqual<PRIOTASK> + Max<CURRCEIL> + Level + Unsigned,
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// {
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// unsafe {
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// match self._state.get() {
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// State::Free => {
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// let c1 = <CURRCEIL>::to_u8();
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// let c2 = <CEILING>::to_u8();
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// if c2 > c1 {
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// let old_basepri = basepri::read();
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// basepri_max::write(<CEILING>::hw());
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// barrier!();
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// self._state.set(State::LockedMut);
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// barrier!();
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//
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// let ret = f(
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// &mut *self.data.get(),
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// &C { _marker: PhantomData },
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// );
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//
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// barrier!();
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// self._state.set(State::Free);
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// barrier!();
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// basepri::write(old_basepri);
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// ret
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// } else {
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// self._state.set(State::LockedMut);
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// barrier!();
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//
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// let ret = f(
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// &mut *self.data.get(),
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// &C { _marker: PhantomData },
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// );
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//
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// barrier!();
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// self._state.set(State::Free);
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// ret
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//
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// }
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// }
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// _ => panic!("Resource already locked)"),
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// }
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// }
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// }
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}
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unsafe impl<T, C> Sync for Res<T, C>
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where
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C: Ceiling,
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{
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}
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/*
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// re-implementation of the original claim API
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impl<T, CEILING> Res<T, C<CEILING>> {
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/// Locks the resource for the duration of the critical section `f`
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@ -357,6 +634,7 @@ where
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{
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}
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*/
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/// A hardware peripheral as a resource
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pub struct Peripheral<P, CEILING>
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where
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