feat: update for ex_9_1

code/exercises/ex_9_1/os.h

@@ -55,8 +55,9 @@ struct context {
 	reg_t t6;
 };
 
-extern int  task_create(void (*task)(void));
+extern int  task_create(void (*task)(void* param), void *param, uint8_t priority);
 extern void task_delay(volatile int count);
 extern void task_yield();
+extern void task_exit();
 
 #endif /* __OS_H__ */

code/exercises/ex_9_1/sched.c

@@ -11,12 +11,22 @@ extern void switch_to(struct context *next);
  */
 uint8_t __attribute__((aligned(16))) task_stack[MAX_TASKS][STACK_SIZE];
 struct context ctx_tasks[MAX_TASKS];
+uint8_t task_priorities[MAX_TASKS];
+
+#define TASK_EMPTY 0
+#define TASK_READY 1
+#define TASK_RUNNING 2
+#define TASK_BLOCKED 3
+#define TASK_EXITED 4
+
+uint8_t task_status[MAX_TASKS];
+
+#define task_schedulable(task_id) (task_status[task_id] == TASK_READY || task_status[task_id] == TASK_RUNNING)
 
 /*
  * _top is used to mark the max available position of ctx_tasks
  * _current is used to point to the context of current task
  */
-static int _top = 0;
 static int _current = -1;
 
 static void w_mscratch(reg_t x)
@@ -27,20 +37,53 @@ static void w_mscratch(reg_t x)
 void sched_init()
 {
 	w_mscratch(0);
+	for (int i = 0; i < MAX_TASKS; i++) {
+		task_status[i] = TASK_EMPTY;
+		task_priorities[i] = 0xff;
+	}
 }
 
 /*
  * implment a simple cycle FIFO schedular
  */
 void schedule()
 {
-	if (_top <= 0) {
-		panic("Num of task should be greater than zero!");
+	// 先扫描获取最高优先级
+	int priority = 0xff;
+	for (int i = 0; i < MAX_TASKS; i++) {
+		if (task_schedulable(i) && task_priorities[i] < priority) {
+			priority = task_priorities[i];
+		}
+	}
+	// printf("priority: %d\n", priority);
+	// 扫描获取最高优先级的任务id，可能有多个，round-robin
+	int next_task_id = -1;
+	for (int i = 0; i < MAX_TASKS; i++) {
+		if (task_schedulable(i) && task_priorities[i] == priority) {
+			if (i > _current) {
+				next_task_id = i;
+				break;
+			}
+		}
+	}
+	if (next_task_id == -1) {
+		for (int i = 0; i < MAX_TASKS; i++) {
+			if (task_schedulable(i) && task_priorities[i] == priority) {
+				next_task_id = i;
+				break;
+			}
+		}
+	}
+	if (next_task_id == -1) {
+		panic("no task to run!\n");
 		return;
 	}
-
-	_current = (_current + 1) % _top;
+	if (next_task_id == _current) {
+		return;
+	}
+	_current = next_task_id;
 	struct context *next = &(ctx_tasks[_current]);
+	task_status[_current] = TASK_RUNNING;
 	switch_to(next);
 }
 
@@ -52,25 +95,46 @@ void schedule()
  * 	0: success
  * 	-1: if error occured
  */
-int task_create(void (*start_routin)(void))
+int task_create(void (*start_routin)(void* param), void* param, uint8_t priority)
 {
-	if (_top < MAX_TASKS) {
-		ctx_tasks[_top].sp = (reg_t) &task_stack[_top][STACK_SIZE];
-		ctx_tasks[_top].ra = (reg_t) start_routin;
-		_top++;
+	int task_id = -1;
+	for (int i = 0; i < MAX_TASKS; i++) {
+		if (task_status[i] == TASK_EMPTY || task_status[i] == TASK_EXITED) {
+			task_id = i;
+			break;
+		}
+	}
+	if (task_id != -1) {
+		ctx_tasks[task_id].sp = (reg_t) &task_stack[task_id][STACK_SIZE];
+		if (param != NULL) {
+			ctx_tasks[task_id].a0 = (reg_t) param;
+		}
+		ctx_tasks[task_id].ra = (reg_t) start_routin;
+		task_priorities[task_id] = priority;
+		task_status[task_id] = TASK_READY;
 		return 0;
 	} else {
 		return -1;
 	}
 }
 
+/*
+ * DESCRIPTION
+ * 	task_exit()  causes the currently executing task to exit.
+ */
+void task_exit(void) {
+	task_status[_current] = TASK_EXITED;
+	schedule();
+}
+
 /*
  * DESCRIPTION
  * 	task_yield()  causes the calling task to relinquish the CPU and a new 
  * 	task gets to run.
  */
 void task_yield()
 {
+	task_status[_current] = TASK_READY;
 	schedule();
 }
 

code/exercises/ex_9_1/user.c

@@ -2,7 +2,7 @@
 
 #define DELAY 1000
 
-void user_task0(void)
+void user_task0(void* param)
 {
 	uart_puts("Task 0: Created!\n");
 	while (1) {
@@ -12,7 +12,7 @@ void user_task0(void)
 	}
 }
 
-void user_task1(void)
+void user_task1(void* param)
 {
 	uart_puts("Task 1: Created!\n");
 	while (1) {
@@ -22,10 +22,33 @@ void user_task1(void)
 	}
 }
 
+void user_task(void* param) {
+	int task_id = (int)param;
+	printf("Task %d: Created!\n", task_id);
+	int iter_cnt = task_id;
+	while (1) {
+		printf("Task %d: Running...\n", task_id);
+		task_delay(DELAY);
+		task_yield();
+		if (iter_cnt-- == 0) {
+			break;
+		}
+	}
+	printf("Task %d: Finished!\n", task_id);
+	task_exit();
+}
+
 /* NOTICE: DON'T LOOP INFINITELY IN main() */
 void os_main(void)
 {
-	task_create(user_task0);
-	task_create(user_task1);
+	// task_create(user_task0, NULL, 255);
+	task_create(user_task1, NULL, 255);
+	task_create(user_task, (void *)3, 0);
+	task_create(user_task, (void *)4, 0);
+	task_create(user_task, (void *)5, 0);
+	task_create(user_task, (void *)6, 1);
+	task_create(user_task, (void *)7, 2);
+	task_create(user_task, (void *)8, 3);
+	task_create(user_task, (void *)9, 4);
+	task_create(user_task, (void *)10, 5);
 }
-