# 编程实例
#### 实例描述
本实例介绍基本的任务操作方法，包含2个不同优先级任务的创建、任务延时、任务锁与解锁调度、挂起和恢复等操作，阐述任务优先级调度的机制以及各接口的应用。
#### 编程示例
前提条件：在menuconfig菜单中完成任务模块的配置。
```
UINT32 g_taskHiId;
UINT32 g_taskLoId;
#define TSK_PRIOR_HI 4
#define TSK_PRIOR_LO 5
UINT32 Example_TaskHi(VOID)
{
    UINT32 ret;
    printf("Enter TaskHi Handler.\r\n");
    /* 延时2个Tick，延时后该任务会挂起，执行剩余任务中最高优先级的任务(g_taskLoId任务) */
    ret = LOS_TaskDelay(2);
    if (ret != LOS_OK) {
        printf("Delay Task Failed.\r\n");
        return LOS_NOK;
    }
    /* 2个Tick时间到了后，该任务恢复，继续执行 */
    printf("TaskHi LOS_TaskDelay Done.\r\n");
    /* 挂起自身任务 */
    ret = LOS_TaskSuspend(g_taskHiId);
    if (ret != LOS_OK) {
        printf("Suspend TaskHi Failed.\r\n");
        return LOS_NOK;
    }
    printf("TaskHi LOS_TaskResume Success.\r\n");
    return ret;
}
/* 低优先级任务入口函数 */
UINT32 Example_TaskLo(VOID)
{
    UINT32 ret;
    printf("Enter TaskLo Handler.\r\n");
    /* 延时2个Tick，延时后该任务会挂起，执行剩余任务中最高优先级的任务(背景任务) */
    ret = LOS_TaskDelay(2);
    if (ret != LOS_OK) {
        printf("Delay TaskLo Failed.\r\n");
        return LOS_NOK;
    }
    printf("TaskHi LOS_TaskSuspend Success.\r\n");
    /* 恢复被挂起的任务g_taskHiId */
    ret = LOS_TaskResume(g_taskHiId);
    if (ret != LOS_OK) {
        printf("Resume TaskHi Failed.\r\n");
        return LOS_NOK;
    }
    printf("TaskHi LOS_TaskDelete Success.\r\n");
    return ret;
}
/* 任务测试入口函数，创建两个不同优先级的任务 */
UINT32 Example_TskCaseEntry(VOID)
{
    UINT32 ret;
    TSK_INIT_PARAM_S initParam;
    /* 锁任务调度，防止新创建的任务比本任务高而发生调度 */
    LOS_TaskLock();
    printf("LOS_TaskLock() Success!\r\n");
    initParam.pfnTaskEntry = (TSK_ENTRY_FUNC)Example_TaskHi;
    initParam.usTaskPrio = TSK_PRIOR_HI;
    initParam.pcName = "TaskHi";
    initParam.uwStackSize = LOSCFG_TASK_MIN_STACK_SIZE;
    initParam.uwResved   = LOS_TASK_STATUS_DETACHED;
    /* 创建高优先级任务，由于锁任务调度，任务创建成功后不会马上执行 */
    ret = LOS_TaskCreate(&g_taskHiId, &initParam);
    if (ret != LOS_OK) {
        LOS_TaskUnlock();
        printf("Example_TaskHi create Failed!\r\n");
        return LOS_NOK;
    }
    printf("Example_TaskHi create Success!\r\n");
    initParam.pfnTaskEntry = (TSK_ENTRY_FUNC)Example_TaskLo;
    initParam.usTaskPrio = TSK_PRIOR_LO;
    initParam.pcName = "TaskLo";
    initParam.uwStackSize = LOSCFG_TASK_MIN_STACK_SIZE;
    initParam.uwResved   = LOS_TASK_STATUS_DETACHED;
    /* 创建低优先级任务，由于锁任务调度，任务创建成功后不会马上执行 */
    ret = LOS_TaskCreate(&g_taskLoId, &initParam);
    if (ret != LOS_OK) {
        LOS_TaskUnlock();
        printf("Example_TaskLo create Failed!\r\n");
        return LOS_NOK;
    }
    printf("Example_TaskLo create Success!\r\n");
    /* 解锁任务调度，此时会发生任务调度，执行就绪队列中最高优先级任务 */
    LOS_TaskUnlock();
    return LOS_OK;
}
```
#### 结果验证
编译运行得到的结果为：
```
LOS_TaskLock() Success!
Example_TaskHi create Success!
Example_TaskLo create Success!
Enter TaskHi Handler.
Enter TaskLo Handler.
TaskHi LOS_TaskDelay Done.
TaskHi LOS_TaskSuspend Success.
TaskHi LOS_TaskResume Success.
TaskHi LOS_TaskDelete Success.
```
#### 完整实例代码
[sample_task.c](https://support.huaweicloud.com/kernelmanual-LiteOS/resource/sample_task.c)