remove claim, add Priority.as_ceiling

build.rs

@@ -56,6 +56,7 @@ fn main() {
 
     // Priorities
     for i in 1..(1 << bits) + 1 {
+        let c = Ident::new(format!("C{}", i));
         let p = Ident::new(format!("P{}", i));
         let u = Ident::new(format!("U{}", i));
 
@@ -64,6 +65,15 @@ fn main() {
                 /// Priority
                 pub type #p = P<::typenum::#u>;
 
+                impl #p {
+                    /// Turns this priority into a ceiling
+                    pub fn as_ceiling(&self) -> &#c {
+                        unsafe {
+                            ::core::mem::transmute(self)
+                        }
+                    }
+                }
+
                 unsafe impl Priority for #p {}
 
                 unsafe impl Level for ::typenum::#u {

src/lib.rs

@@ -18,7 +18,7 @@ use cortex_m::interrupt::Nr;
 #[cfg(not(thumbv6m))]
 use cortex_m::register::{basepri, basepri_max};
 use static_ref::Ref;
-use typenum::{Cmp, Equal, Unsigned};
+use typenum::{Cmp, Unsigned};
 #[cfg(not(thumbv6m))]
 use typenum::{Greater, Less};
 
@@ -74,19 +74,6 @@ impl<T, CEILING> Resource<T, C<CEILING>> {
         unsafe { Ref::new(&*self.data.get()) }
     }
 
-    /// Claims the resource at the task with highest priority
-    ///
-    /// This operation is zero cost and doesn't impose any additional blocking
-    pub fn claim<'task, PRIORITY>(
-        &'static self,
-        _priority: &'task P<PRIORITY>,
-    ) -> Ref<'task, T>
-    where
-        CEILING: Cmp<PRIORITY, Output = Equal>,
-    {
-        unsafe { Ref::new(&*self.data.get()) }
-    }
-
     /// Locks the resource for the duration of the critical section `f`
     ///
     /// For the duration of the critical section, tasks whose priority level is
@@ -161,17 +148,6 @@ impl<Periph, CEILING> Peripheral<Periph, C<CEILING>> {
         unsafe { Ref::new(&*self.peripheral.get()) }
     }
 
-    /// See [Resource.claim](./struct.Resource.html#method.claim)
-    pub fn claim<'task, PRIORITY>(
-        &'static self,
-        _priority: &'task P<PRIORITY>,
-    ) -> Ref<'task, Periph>
-    where
-        CEILING: Cmp<PRIORITY, Output = Equal>,
-    {
-        unsafe { Ref::new(&*self.peripheral.get()) }
-    }
-
     /// See [Resource.lock](./struct.Resource.html#method.lock)
     #[cfg(not(thumbv6m))]
     pub fn lock<R, PRIORITY, F>(&'static self, _priority: &P<PRIORITY>, f: F) -> R

tests/cfail/lock.rs

@@ -11,13 +11,13 @@ fn j1(prio: P3) {
 }
 
 // DON'T lock a resource with ceiling equal to the task priority.
-// Instead use `claim`
+// Instead use `borrow`
 fn j2(prio: P2) {
     R1.lock(&prio, |_, _| {});
     //~^ error
 
     // OK
-    let r1 = R1.claim(&prio);
+    let r1 = R1.borrow(&prio, prio.as_ceiling());
 }
 
 // You CAN lock a resource with ceiling C from a task with priority P if C > P
@@ -37,5 +37,5 @@ fn j4(prio: P1) {
 // Only tasks with priority P16 can claim a resource with ceiling C16
 fn j5(prio: P16) {
     // OK
-    let r2 = R2.claim(&prio);
+    let r2 = R2.borrow(&prio, prio.as_ceiling());
 }