Refactor and rewrite

src/multitasking/mod.rs

@@ -0,0 +1,20 @@
+use scheduler::Scheduler;
+
+pub mod thread;
+pub mod scheduler;
+pub mod context_switch;
+
+static SCHEDULER: spin::Mutex<Option<Scheduler>> = spin::Mutex::new(None);
+
+pub fn invoke_scheduler() {
+    let next = SCHEDULER
+        .try_lock()
+        .and_then(|mut scheduler| scheduler.as_mut().and_then(|s| s.schedule()));
+    if let Some((next_id, next_stack_pointer)) = next {
+        unsafe { context_switch::context_switch_to(next_id, next_stack_pointer) };
+    }
+}
+
+pub fn with_scheduler<F, T>(f: F) -> T where F: FnOnce(&mut Scheduler) -> T {
+    f(SCHEDULER.lock().get_or_insert_with(Scheduler::new))
+}