目录
前言
- 20201009
- LiteOS 2018
- 需要会通用链表
链接
- LiteOS源码链接
- 常见问题
- 华为开发者社区
- 华为LiteOS官方教程
- 我的源码
- 包含 裸机源码
- LiteOS 工程模板
- 其它关于 LiteOS 的 demo 及 note
参考
- 上面链接
笔录草稿
部分源码分析
源码分析
LOS_TaskCreate函数
- 需要一个 任务初始化参数结构体
TSK_INIT_PARAM_S和 一个任务句柄。 - TSK_INIT_PARAM_S 源码
/**
* @ingroup los_task
* Define the structure of the parameters used for task creation.
*
* Information of specified parameters passed in during task creation.
*/
typedef struct tagTskInitParam
{
TSK_ENTRY_FUNC pfnTaskEntry; /**< Task entrance function */
UINT16 usTaskPrio; /**< Task priority */
UINT32 uwArg; /**< Task parameters */
UINT32 uwStackSize; /**< Task stack size */
CHAR *pcName; /**< Task name */
UINT32 uwResved; /**< Reserved */
} TSK_INIT_PARAM_S;
- LOS_TaskCreate 函数源码
- 内含解读
/*****************************************************************************
Function : LOS_TaskCreate
Description : Create a task
Input : pstInitParam --- Task init parameters
Output : puwTaskID --- Save task ID
Return : LOS_OK on success or error code on failure
*****************************************************************************/
LITE_OS_SEC_TEXT_INIT UINT32 LOS_TaskCreate(UINT32 *puwTaskID, TSK_INIT_PARAM_S *pstInitParam)
{
UINT32 uwRet = LOS_OK;
UINTPTR uvIntSave;
LOS_TASK_CB *pstTaskCB; // 定义一个任务控制块
uwRet = LOS_TaskCreateOnly(puwTaskID, pstInitParam); // 以挂起的方式创建一个新的任务（即是阻塞态）
if (LOS_OK != uwRet)
{
return uwRet;
}
pstTaskCB = OS_TCB_FROM_TID(*puwTaskID); // 通过任务 ID 获取 TCB 句柄
uvIntSave = LOS_IntLock(); // 锁任务
pstTaskCB->usTaskStatus &= (~OS_TASK_STATUS_SUSPEND);
pstTaskCB->usTaskStatus |= OS_TASK_STATUS_READY; // 解除阻塞-->进入就绪
#if (LOSCFG_BASE_CORE_CPUP == YES) // CPU 利用率模块代码段
g_pstCpup[pstTaskCB->uwTaskID].uwID = pstTaskCB->uwTaskID;
g_pstCpup[pstTaskCB->uwTaskID].usStatus = pstTaskCB->usTaskStatus;
#endif
osPriqueueEnqueue(&pstTaskCB->stPendList, pstTaskCB->usPriority); // 将该任务插入 优先级队列 ，即是 就绪列表
g_stLosTask.pstNewTask = LOS_DL_LIST_ENTRY(osPriqueueTop(), LOS_TASK_CB, stPendList); /*lint !e413*/ /* 找出已经创建的任务中最高优先级、最先插入的 TCB */
/* 以下只是判断是否需要调度而已 */
/* 如果系统开启了调度，且，锁任务关闭，则，进入二次判断 */
if ((g_bTaskScheduled) && (g_usLosTaskLock == 0))
{
/* 如果最高优先级、最先插入的任务不在运行态，则进行调度 */
if (g_stLosTask.pstRunTask != g_stLosTask.pstNewTask)
{
if (LOS_CHECK_SCHEDULE)
{
(VOID)LOS_IntRestore(uvIntSave);
osSchedule();
return LOS_OK;
}
}
}
/* 解锁任务调度 */
(VOID)LOS_IntRestore(uvIntSave);
return LOS_OK;
}
LOS_TaskCreateOnly函数
- g_stTskRecyleList
- 任务可回收链表
- g_stLosFreeTask
- 任务可用链表
/*****************************************************************************
Function : LOS_TaskCreateOnly
Description : Create a task and suspend
Input : pstInitParam --- Task init parameters
Output : puwTaskID --- Save task ID
Return : LOS_OK on success or error code on failure
*****************************************************************************/
LITE_OS_SEC_TEXT_INIT UINT32 LOS_TaskCreateOnly(UINT32 *puwTaskID, TSK_INIT_PARAM_S *pstInitParam)
{
UINT32 uwTaskID = 0;
UINTPTR uvIntSave;
VOID *pTopStack;
VOID *pStackPtr;
LOS_TASK_CB *pstTaskCB;
UINT32 uwErrRet = OS_ERROR;
/* 元素合法检查 [start][A] */
if (NULL == puwTaskID)
{
return LOS_ERRNO_TSK_ID_INVALID;
}
if (NULL == pstInitParam)
{
return LOS_ERRNO_TSK_PTR_NULL;
}
if (NULL == pstInitParam->pcName)
{
return LOS_ERRNO_TSK_NAME_EMPTY;
}
if (NULL == pstInitParam->pfnTaskEntry)
{
return LOS_ERRNO_TSK_ENTRY_NULL;
}
if ((pstInitParam->usTaskPrio) > OS_TASK_PRIORITY_LOWEST)
{
return LOS_ERRNO_TSK_PRIOR_ERROR;
}
if (((pstInitParam->usTaskPrio) == OS_TASK_PRIORITY_LOWEST)
&& (pstInitParam->pfnTaskEntry != OS_IDLE_TASK_ENTRY))
{
return LOS_ERRNO_TSK_PRIOR_ERROR;
}
if (pstInitParam->uwStackSize > OS_SYS_MEM_SIZE)
{
return LOS_ERRNO_TSK_STKSZ_TOO_LARGE;
}
if (0 == pstInitParam->uwStackSize)
{
pstInitParam->uwStackSize = LOSCFG_BASE_CORE_TSK_DEFAULT_STACK_SIZE;
}
pstInitParam->uwStackSize = ALIGN(pstInitParam->uwStackSize , 8);
if (pstInitParam->uwStackSize < LOSCFG_BASE_CORE_TSK_MIN_STACK_SIZE)
{
return LOS_ERRNO_TSK_STKSZ_TOO_SMALL;
}
/* 元素合法检查 [end][A] */
uvIntSave = LOS_IntLock(); // 锁任务
/* 处理任务可回收链表，释放出可用任务空间 */
while (!LOS_ListEmpty(&g_stTskRecyleList))
{
pstTaskCB = OS_TCB_FROM_PENDLIST(LOS_DL_LIST_FIRST(&g_stTskRecyleList)); /*lint !e413*/ /* 获取任务 可回收链表 中的 第一个 TCB。 *后面有源码分析* */
LOS_ListDelete(LOS_DL_LIST_FIRST(&g_stTskRecyleList)); // 从该链表中删除该节点
LOS_ListAdd(&g_stLosFreeTask, &pstTaskCB->stPendList); // 把该任块放到 可用链表 中
(VOID)LOS_MemFree(m_aucSysMem0, (VOID *)pstTaskCB->uwTopOfStack); // 释放该任务申请的任务栈空间
pstTaskCB->uwTopOfStack = (UINT32)NULL;// 初始化该任务块栈顶指针
}
/* 判断是否还有可用任务块使用，若没有，则，退出 */
if (LOS_ListEmpty(&g_stLosFreeTask))
{
uwErrRet = LOS_ERRNO_TSK_TCB_UNAVAILABLE;
OS_GOTO_ERREND();
}
pstTaskCB = OS_TCB_FROM_PENDLIST(LOS_DL_LIST_FIRST(&g_stLosFreeTask)); /*lint !e413*/ /* 获取 可用链表 中第一个节点对应的 TCB。*后面有源码分析* */
LOS_ListDelete(LOS_DL_LIST_FIRST(&g_stLosFreeTask)); // 上面获取后，便从 可用链表 中删除该节点。
(VOID)LOS_IntRestore(uvIntSave); // 解锁任务
uwTaskID = pstTaskCB->uwTaskID; // 获取 ID
pTopStack = (VOID *)LOS_MemAllocAlign(m_aucSysMem0, pstInitParam->uwStackSize, 8); // 申请动态内存，8 字节对齐
if (NULL == pTopStack) // 申请失败
{
uvIntSave = LOS_IntLock();
LOS_ListAdd(&g_stLosFreeTask, &pstTaskCB->stPendList);
uwErrRet = LOS_ERRNO_TSK_NO_MEMORY;
OS_GOTO_ERREND();
}
/* 申请成功 */
/* 初始化 TCB */
pStackPtr = osTskStackInit(uwTaskID, pstInitParam->uwStackSize, pTopStack);
pstTaskCB->pStackPointer = pStackPtr;
pstTaskCB->uwArg = pstInitParam->uwArg;
pstTaskCB->uwTopOfStack = (UINT32)pTopStack;
pstTaskCB->uwStackSize = pstInitParam->uwStackSize;
pstTaskCB->pTaskSem = NULL;
pstTaskCB->pTaskMux = NULL;
pstTaskCB->usTaskStatus = OS_TASK_STATUS_SUSPEND;
pstTaskCB->usPriority = pstInitParam->usTaskPrio;
pstTaskCB->pfnTaskEntry = pstInitParam->pfnTaskEntry;
pstTaskCB->uwEvent.uwEventID = 0xFFFFFFFF;
pstTaskCB->uwEventMask = 0;
pstTaskCB->pcTaskName = pstInitParam->pcName;
pstTaskCB->puwMsg = NULL;
*puwTaskID = uwTaskID; /* 更新 ID，返回给上层 */
return LOS_OK; /* 创建成功 */
LOS_ERREND:
(VOID)LOS_IntRestore(uvIntSave);
return uwErrRet;
}
宏 OS_TCB_FROM_PENDLIST 和 宏 LOS_DL_LIST_FIRST
- OS_TCB_FROM_PENDLIST
- 获取 链接因子 ptr 中所在的任务控制块的首地址
- 意思就是：获取某条 stPendList 链表 中 ptr 节点的 TCB句柄
/**
* @ingroup los_task
* @brief Obtain the pointer to a task control block.
* @par Description:
* This API is used to obtain the pointer to a task control block using a corresponding parameter.
* @param ptr [IN] Parameter used for obtaining the task control block.
* @retval Pointer to the task control block.
*/
#define OS_TCB_FROM_PENDLIST(ptr) LOS_DL_LIST_ENTRY(ptr, LOS_TASK_CB, stPendList)
- LOS_DL_LIST_ENTRY
- 通用链表的算法
- 获取链接因子 item 所在的数据块的首地址
/**
*@ingroup los_list
*@brief Obtain the pointer to a structure that contains a doubly linked list.
*@par Description:
*This API is used to obtain the pointer to a structure that contains a doubly linked list.
*@param item [IN] Current node's pointer to the next node.
*@param type [IN] Structure name.
*@param member [IN] Member name of the doubly linked list in the structure.
*@retval Pointer to the structure that contains the doubly linked list.
*/
#define LOS_DL_LIST_ENTRY(item, type, member) \
((type *)((char *)item - LOS_OFF_SET_OF(type, member))) \
- LOS_OFF_SET_OF
- 通用链表的算法
- 算出 结构体首地址 到 成员 之间的便宜。
/**
*@ingroup los_list
*@brief Obtain the pointer to a doubly linked list in a structure.
*@par Description:
*This API is used to obtain the pointer to a doubly linked list in a structure.
*@param type [IN] Structure name.
*@param member [IN] Member name of the doubly linked list in the structure.
*@retval Pointer to the doubly linked list in the structure.
*/
#define LOS_OFF_SET_OF(type, member) ((long)&((type *)0)->member) /*lint -e(413) */
任务控制块 LOS_TASK_CB
/**
* @ingroup los_task
* Define the task control block structure.
*/
typedef struct tagTaskCB
{
VOID *pStackPointer; /**< Task stack pointer */
UINT16 usTaskStatus;
UINT16 usPriority;
UINT32 uwStackSize; /**< Task stack size */
UINT32 uwTopOfStack; /**< Task stack top */
UINT32 uwTaskID; /**< Task ID */
TSK_ENTRY_FUNC pfnTaskEntry; /**< Task entrance function */
VOID *pTaskSem; /**< Task-held semaphore */
VOID *pTaskMux; /**< Task-held mutex */
UINT32 uwArg; /**< Parameter */
CHAR *pcTaskName; /**< Task name */
LOS_DL_LIST stPendList;
LOS_DL_LIST stTimerList;
UINT32 uwIdxRollNum;
EVENT_CB_S uwEvent;
UINT32 uwEventMask; /**< Event mask */
UINT32 uwEventMode; /**< Event mode */
VOID *puwMsg; /**< Memory allocated to queues */
} LOS_TASK_CB;