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-rw-r--r--examples/lockopt.rs67
1 files changed, 67 insertions, 0 deletions
diff --git a/examples/lockopt.rs b/examples/lockopt.rs
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+//! examples/optlock.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use panic_semihosting as _;
+use rtfm::Exclusive;
+
+#[rtfm::app(device = lm3s6965)]
+const APP: () = {
+ struct Resources {
+ #[init(0)]
+ shared: u32,
+ }
+
+ #[init]
+ fn init(_: init::Context) {
+ rtfm::pend(Interrupt::GPIOA);
+ }
+
+ // when omitted priority is assumed to be `1`
+ #[task(binds = GPIOA, resources = [shared])]
+ fn gpioa(mut c: gpioa::Context) {
+ // the lower priority task requires a critical section to access the data
+ c.resources.shared.lock(|shared| {
+ // data can only be modified within this critical section (closure)
+ *shared += 1;
+
+ // GPIOB will *not* run right now due to the critical section
+ rtfm::pend(Interrupt::GPIOB);
+
+ // hprintln!("B - shared = {}", *shared).unwrap();
+
+ // GPIOC does not contend for `shared` so it's allowed to run now
+ rtfm::pend(Interrupt::GPIOC);
+ });
+
+ // critical section is over: GPIOB can now start
+
+ debug::exit(debug::EXIT_SUCCESS);
+ }
+
+ #[task(binds = GPIOB, priority = 2, resources = [shared])]
+ fn gpiob(mut c: gpiob::Context) {
+ // higher priority task, with critical section
+ c.resources.shared.lock(|shared| {
+ *shared += 1;
+ });
+ }
+
+ #[task(binds = GPIOC, priority = 3, resources = [shared])]
+ fn gpioc(c: gpioc::Context) {
+ // highest priority task with critical section
+ // we wrap resource.shared into an Exclusive
+ let mut exclusive = Exclusive(c.resources.shared);
+ // we can access through both lock ...
+ exclusive.lock(|shared| {
+ *shared += 1;
+ });
+ // and deref, i.e., non-orthogonal design
+ *exclusive += 1;
+ }
+};