设定任务优先级（2）

16_day/bootpack.c

@@ -51,6 +51,7 @@ void HariMain(void)
 	shtctl = shtctl_init(memman, binfo->vram, binfo->scrnx, binfo->scrny);
 	task_a = task_init(memman);
 	fifo.task = task_a;
+	task_run(task_a, 1, 0);
 
 	/* sht_back */
 	sht_back  = sheet_alloc(shtctl);
@@ -75,7 +76,7 @@ void HariMain(void)
 		task_b[i]->tss.fs = 1 * 8;
 		task_b[i]->tss.gs = 1 * 8;
 		*((int *) (task_b[i]->tss.esp + 4)) = (int) sht_win_b[i];
-		task_run(task_b[i]);
+		task_run(task_b[i], 2, i + 1);
 	}
 
 	/* sht_win */

16_day/bootpack.h

@@ -188,6 +188,8 @@ void inthandler20(int *esp);
 /* mtask.c */
 #define MAX_TASKS 1000	/*最大任务数量*/
 #define TASK_GDT0 3			/*定义从GDT的几号开始分配给TSS */
+#define MAX_TASKS_LV    100
+#define MAX_TASKLEVELS  10
 struct TSS32 {
 	int backlink, esp0, ss0, esp1, ss1, esp2, ss2, cr3;
 	int eip, eflags, eax, ecx, edx, ebx, esp, ebp, esi, edi;
@@ -196,17 +198,23 @@ struct TSS32 {
 };
 struct TASK {
 	int sel, flags;		/* sel用来存放GDT的编号*/
+	int level, priority; /* 优先级 */
 	struct TSS32 tss;
 };
+struct TASKLEVEL {
+	int running; /*正在运行的任务数量*/
+	int now; /*这个变量用来记录当前正在运行的是哪个任务*/
+	struct TASK *tasks[MAX_TASKS_LV];
+};
 struct TASKCTL {
-	int running;		/*正在运行的任务数量*/
-	int now;				/*这个变量用来记录当前正在运行的是哪个任务*/
-	struct TASK *tasks[MAX_TASKS];
+	int now_lv; /*现在活动中的LEVEL */
+	char lv_change; /*在下次任务切换时是否需要改变LEVEL */
+	struct TASKLEVEL level[MAX_TASKLEVELS];
 	struct TASK tasks0[MAX_TASKS];
 };
 extern struct TIMER *task_timer;
 struct TASK *task_init(struct MEMMAN *memman);
 struct TASK *task_alloc(void);
-void task_run(struct TASK *task);
+void task_run(struct TASK *task, int level, int priority);
 void task_switch(void);
 void task_sleep(struct TASK *task);

16_day/fifo.c

@@ -18,7 +18,7 @@ void fifo32_init(struct FIFO32 *fifo, int size, int *buf, struct TASK *task)
 }
 
 int fifo32_put(struct FIFO32 *fifo, int data)
-/*给FIFO发送数据并储存在FIFO中*/
+/*向FIFO写入数据并累积起来*/
 {
 	if (fifo->free == 0) {
 		/*没有空余空间，溢出*/
@@ -33,7 +33,7 @@ int fifo32_put(struct FIFO32 *fifo, int data)
 	fifo->free--;
 	if (fifo->task != 0) {
 		if (fifo->task->flags != 2) { /*如果任务处于休眠状态*/
-			task_run(fifo->task); /*将任务唤醒*/
+			task_run(fifo->task, -1, 0); /*将任务唤醒*/
 		}
 	}
 	return 0;

16_day/mtask.c

@@ -5,6 +5,65 @@
 struct TASKCTL *taskctl;
 struct TIMER *task_timer;
 
+struct TASK *task_now(void)
+{
+	struct TASKLEVEL *tl = &taskctl->level[taskctl->now_lv];
+	return tl->tasks[tl->now];
+}
+
+void task_add(struct TASK *task)
+{
+	struct TASKLEVEL *tl = &taskctl->level[task->level];
+	tl->tasks[tl->running] = task;
+	tl->running++;
+	task->flags = 2; /*活动中*/
+	return;
+}
+
+void task_remove(struct TASK *task)
+{
+	int i;
+	struct TASKLEVEL *tl = &taskctl->level[task->level];
+
+	/*寻找task所在的位置*/
+	for (i = 0; i < tl->running; i++) {
+		if (tl->tasks[i] == task) {
+			/*在这里 */
+			break;
+		}
+	}
+
+	tl->running--;
+	if (i < tl->now) {
+		tl->now--; /*需要移动成员，要相应地处理 */
+	}
+	if (tl->now >= tl->running) {
+		/*如果now的值出现异常，则进行修正*/
+		tl->now = 0;
+	}
+	task->flags = 1; /* 休眠中 */
+
+	/* 移动 */
+	for (; i < tl->running; i++) {
+		tl->tasks[i] = tl->tasks[i + 1];
+	}
+	return;
+}
+
+void task_switchsub(void)
+{
+	int i;
+	/*寻找最上层的LEVEL */
+	for (i = 0; i < MAX_TASKLEVELS; i++) {
+		if (taskctl->level[i].running > 0) {
+			break; /*找到了*/
+		}
+	}
+	taskctl->now_lv = i;
+	taskctl->lv_change = 0;
+	return;
+}
+
 struct TASK *task_init(struct MEMMAN *memman)
 {
 	int i;
@@ -17,15 +76,19 @@ struct TASK *task_init(struct MEMMAN *memman)
 		taskctl->tasks0[i].sel = (TASK_GDT0 + i) * 8;
 		set_segmdesc(gdt + TASK_GDT0 + i, 103, (int) &taskctl->tasks0[i].tss, AR_TSS32);
 	}
-
+	for (i = 0; i < MAX_TASKLEVELS; i++) {
+		taskctl->level[i].running = 0;
+		taskctl->level[i].now = 0;
+	}
 	task = task_alloc();
 	task->flags = 2; /*活动中标志*/
-	taskctl->running = 1;
-	taskctl->now = 0;
-	taskctl->tasks[0] = task;
+	task->priority = 2; /* 0.02秒*/
+	task->level = 0; /*最高LEVEL */
+	task_add(task);
+	task_switchsub(); /* LEVEL 设置*/
 	load_tr(task->sel);
 	task_timer = timer_alloc();
-	timer_settime(task_timer, 2);
+	timer_settime(task_timer, task->priority);
 	return task;
 }
 
@@ -57,58 +120,59 @@ struct TASK *task_alloc(void)
 	return 0; /*全部正在使用*/
 }
 
-void task_run(struct TASK *task)
+void task_run(struct TASK *task, int level, int priority)
 {
-	task->flags = 2; /*活动中标志*/
-	taskctl->tasks[taskctl->running] = task;
-	taskctl->running++;
+	if (level < 0) {
+		level = task->level; /*不改变LEVEL */
+	}
+	if (priority > 0) {
+		task->priority = priority;
+	}
+	if (task->flags == 2 && task->level != level) { 
+		/*改变活动中的LEVEL */
+		task_remove(task); /*这里执行之后flag的值会变为1，于是下面的if语句块也会被执行*/
+	}
+	if (task->flags != 2) {
+		/*从休眠状态唤醒的情形*/
+		task->level = level;
+		task_add(task);
+	}
+	taskctl->lv_change = 1; /*下次任务切换时检查LEVEL */
 	return;
 }
 
 void task_switch(void)
 {
-	timer_settime(task_timer, 2);
-	if (taskctl->running >= 2) {
-		taskctl->now++;
-		if (taskctl->now == taskctl->running) {
-			taskctl->now = 0;
-		}
-		farjmp(0, taskctl->tasks[taskctl->now]->sel);
+	struct TASKLEVEL *tl = &taskctl->level[taskctl->now_lv];
+	struct TASK *new_task, *now_task = tl->tasks[tl->now];
+	tl->now++;
+	if (tl->now == tl->running) {
+		tl->now = 0;
+	}
+	if (taskctl->lv_change != 0) {
+		task_switchsub();
+		tl = &taskctl->level[taskctl->now_lv];
+	}
+	new_task = tl->tasks[tl->now];
+	timer_settime(task_timer, new_task->priority);
+	if (new_task != now_task) {
+		farjmp(0, new_task->sel);
 	}
 	return;
 }
 
 void task_sleep(struct TASK *task)
 {
-	int i;
-	char ts = 0;
-	if (task->flags == 2) { /*如果指定任务处于唤醒状态*/
-		if (task == taskctl->tasks[taskctl->now]) {
-			ts = 1; /*让自己休眠的话，稍后需要进行任务切换*/
-		}
-		/*寻找task所在的位置*/
-		for (i = 0; i < taskctl->running; i++) {
-			if (taskctl->tasks[i] == task) {
-				/*在这里*/
-				break;
-			}
-		}
-		taskctl->running--;
-		if (i < taskctl->now) {
-			taskctl->now--; /*需要移动成员，要相应地处理*/
-		}
-		/*移动成员*/
-		for (; i < taskctl->running; i++) {
-			taskctl->tasks[i] = taskctl->tasks[i + 1];
-		}
-		task->flags = 1; /*不工作的状态*/
-		if (ts != 0) {
-			/*任务切换*/
-			if (taskctl->now >= taskctl->running) {
-				/*如果now的值出现异常，则进行修正*/
-				taskctl->now = 0;
-			}
-			farjmp(0, taskctl->tasks[taskctl->now]->sel);
+	struct TASK *now_task;
+	if (task->flags == 2) {
+		/*如果处于活动状态*/
+		now_task = task_now();
+		task_remove(task); /*执行此语句的话flags将变为1 */
+		if (task == now_task) {
+			/*如果是让自己休眠，则需要进行任务切换*/
+			task_switchsub();
+			now_task = task_now(); /*在设定后获取当前任务的值*/
+			farjmp(0, now_task->sel);
 		}
 	}
 	return;