Split TaskManager and Processor.

os/src/task/manager.rs

@@ -0,0 +1,34 @@
+use super::TaskControlBlock;
+use alloc::collections::VecDeque;
+use alloc::sync::Arc;
+use spin::Mutex;
+use lazy_static::*;
+
+pub struct TaskManager {
+    ready_queue: VecDeque<Arc<Mutex<TaskControlBlock>>>,
+}
+
+/// A simple FIFO scheduler.
+impl TaskManager {
+    pub fn new() -> Self {
+        Self { ready_queue: VecDeque::new(), }
+    }
+    pub fn add(&mut self, task: Arc<Mutex<TaskControlBlock>>) {
+        self.ready_queue.push_back(task);
+    }
+    pub fn fetch(&mut self) -> Option<Arc<Mutex<TaskControlBlock>>> {
+        self.ready_queue.pop_front()
+    }
+}
+
+lazy_static! {
+    pub static ref TASK_MANAGER: Mutex<TaskManager> = Mutex::new(TaskManager::new());
+}
+
+pub fn add_task(task: Arc<Mutex<TaskControlBlock>>) {
+    TASK_MANAGER.lock().add(task);
+}
+
+pub fn fetch_task() -> Option<Arc<Mutex<TaskControlBlock>>> {
+    TASK_MANAGER.lock().fetch()
+}