rt-thread採用內核對象管理系統來訪問和管理所有內核對象.首先來看看rt-thread的內核對象是如何定義的:
1 數據結構
1.1 對象控制塊
在include/rtdef.h頭文件中可以找到內核對象有結構定義:
/**
* Base structure of Kernel object
*/
struct rt_object
{
char name[RT_NAME_MAX];//名稱
rt_uint8_t type;//內核對象類型
rt_uint8_t flag;//內核對象標誌
#ifdef RT_USING_MODULE
void *module_id;//模塊ID
#endif
rt_list_t list;//內核對象鏈表節點
};
typedef struct rt_object *rt_object_t;
這裏需要注意地是,上述內核對象控制塊包含了一rt_list_t類型的成員list,這個是一鏈表節點,便於將此內核對象加入到一鏈表中,其結構如下定義:
struct rt_list_node
{
struct rt_list_node *next; //指向下一節點
struct rt_list_node *prev; //指向前一節點
};
typedef struct rt_list_node rt_list_t;
另內核對象類型取值有如下類型:
/**
* The object type can be one of the follows with specific
* macros enabled:
* - Thread
* - Semaphore
* - Mutex
* - Event
* - MailBox
* - MessageQueue
* - MemHeap
* - MemPool
* - Device
* - Timer
* - Module
* - Unknown
* - Static
*/
enum rt_object_class_type
{
RT_Object_Class_Thread = 0, //線程
#ifdef RT_USING_SEMAPHORE
RT_Object_Class_Semaphore, //信號量
#endif
#ifdef RT_USING_MUTEX
RT_Object_Class_Mutex, //互斥鎖
#endif
#ifdef RT_USING_EVENT
RT_Object_Class_Event, //事件
#endif
#ifdef RT_USING_MAILBOX
RT_Object_Class_MailBox, //郵箱
#endif
#ifdef RT_USING_MESSAGEQUEUE
RT_Object_Class_MessageQueue, //消息隊列
#endif
#ifdef RT_USING_MEMHEAP
RT_Object_Class_MemHeap, //內存堆
#endif
#ifdef RT_USING_MEMPOOL
RT_Object_Class_MemPool, //內存池
#endif
#ifdef RT_USING_DEVICE
RT_Object_Class_Device, //設備驅動
#endif
RT_Object_Class_Timer, //時鐘
#ifdef RT_USING_MODULE
RT_Object_Class_Module, //模塊
#endif
RT_Object_Class_Unknown, //未知內核對象類型
RT_Object_Class_Static = 0x80 //rt-thread以此位標誌是否爲系統內核對象
};
需要注意的是,rt-thread將內核對象的type的最高位若爲1,則表示此內核對象爲系統內核對象,否則非系統內核對象.
1.2 內核對象容器
RTT使用內核對象容器來管理同一類型的內核對象,並將其放入同一鏈表中,便於訪問.內核對象信息的結構如下定義:
/**
* The information of the kernel object
*/
struct rt_object_information
{
enum rt_object_class_type type; //內核對象類型
rt_list_t object_list; //內核對象鏈表
rt_size_t object_size; //內核對象所佔的大小
};
1.3 內核對象管理系統
RTT中,每一類型的內核對象都會有一內核對象容器來包容,這個類型的內核對象容器實際上是用一鏈表(見1.2節所示的內核對象容器結構定義),這個鏈表將所有相同類型的內核對象鏈接起來.由於每一類型都對應着有一個這樣的內核對象容器來管理,那麼所有內核對象容器整體就叫做內核對象管理系統.
如下圖示：
RTT中,內核對象管理系統是用一個rt_object_information數組來實現的,如下:
#define _OBJ_CONTAINER_LIST_INIT(c)\//內核對象容器的鏈表初始化,這裏用一個宏來定義,鏈表的前一節點和後一節點在初始化時都指向本身所在地址
{&(rt_object_container[c].object_list), &(rt_object_container[c].object_list)}
//內核對象管理系統,這裏用rt_object_information數組來實現
struct rt_object_information rt_object_container[RT_Object_Class_Unknown] =
{
/* initialize object container - thread */)},//線程對象信息
{RT_Object_Class_Thread, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Thread), sizeof(struct rt_thread#ifdef RT_USING_SEMAPHORE
/* initialize object container - semaphore *///信號量對象信息
{RT_Object_Class_Semaphore, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Semaphore), sizeof(struct rt_semaphore)},
#endif
#ifdef RT_USING_MUTEX
/* initialize object container - mutex *///互斥鎖對象信息
{RT_Object_Class_Mutex, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Mutex), sizeof(struct rt_mutex)},
#endif
#ifdef RT_USING_EVENT
/* initialize object container - event *///事件對象信息
{RT_Object_Class_Event, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Event), sizeof(struct rt_event)},
#endif
#ifdef RT_USING_MAILBOX
/* initialize object container - mailbox *///郵箱對象信息
{RT_Object_Class_MailBox, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MailBox), sizeof(struct rt_mailbox)},
#endif
#ifdef RT_USING_MESSAGEQUEUE
/* initialize object container - message queue *///消息隊列對象信息
{RT_Object_Class_MessageQueue, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MessageQueue), sizeof(struct rt_messagequeue)},
#endif
#ifdef RT_USING_MEMHEAP
/* initialize object container - memory heap *///內存堆對象信息
{RT_Object_Class_MemHeap, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MemHeap), sizeof(struct rt_memheap)},
#endif
#ifdef RT_USING_MEMPOOL
/* initialize object container - memory pool *///內存池對象信息
{RT_Object_Class_MemPool, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_MemPool), sizeof(struct rt_mempool)},
#endif
#ifdef RT_USING_DEVICE
/* initialize object container - device *///設備驅動對象信息
{RT_Object_Class_Device, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Device), sizeof(struct rt_device)},
#endif
/* initialize object container - timer *///時鐘對象信息
{RT_Object_Class_Timer, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Timer), sizeof(struct rt_timer)},
#ifdef RT_USING_MODULE
/* initialize object container - module *///模塊對象信息
{RT_Object_Class_Module, _OBJ_CONTAINER_LIST_INIT(RT_Object_Class_Module), sizeof(struct rt_module)},
#endif
};
2 內核對象接口
2.1 內核對象初始化
RTT提供靜態和動態兩種初始化接口,如下:
靜態初始化是將一個已經存在的且佔有內存空間的對象初始化,它的接口如下:
/**
* This function will initialize an object and add it to object system
* management.
*
* @param object the specified object to be initialized.
* @param type the object type.
* @param name the object name. In system, the object's name must be unique.
*/
void rt_object_init(struct rt_object *object,//指向已存在的對象指針
enum rt_object_class_type type, //對象的類型
const char *name) //對象的名字字符串
{
register rt_base_t temp;
struct rt_object_information *information; //對象容器
#ifdef RT_USING_MODULE //如果使用了模塊,那麼對象容器指向本線程所包含的對象窗口,否則指向全局對象管理系統中對應的容器
/* get module object information */
information = (rt_module_self() != RT_NULL) ?
&rt_module_self()->module_object[type] : &rt_object_container[type];
#else
/* get object information */
information = &rt_object_container[type];
#endif
/* initialize object's parameters */
/* set object type to static */
object->type = type | RT_Object_Class_Static;//設置系統對象標誌
/* copy name */
rt_strncpy(object->name, name, RT_NAME_MAX);//給名字賦值
RT_OBJECT_HOOK_CALL(rt_object_attach_hook, (object));//使用鉤子函數
/* lock interrupt */
temp = rt_hw_interrupt_disable();//關中斷
/* insert object into information object list */
rt_list_insert_after(&(information->object_list), &(object->list));//將初始化的內核對象加入到對應容器中
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//開中斷
}
動態初始化是指對象原本並不存在,在不內存中,需要動態爲其分配內存,其接口如下:
/**
* This function will allocate an object from object system
*
* @param type the type of object
* @param name the object name. In system, the object's name must be unique.
*
* @return object
*/
rt_object_t rt_object_allocate(enum rt_object_class_type type, const char *name)//動態初始化接口只需要傳入名字和類型
{
struct rt_object *object;
register rt_base_t temp;
struct rt_object_information *information;//對象容器
RT_DEBUG_NOT_IN_INTERRUPT;
#ifdef RT_USING_MODULE//同上面那個接口一樣,獲取對象容器
/*
* get module object information,
* module object should be managed by kernel object container
*/
information = (rt_module_self() != RT_NULL && (type != RT_Object_Class_Module)) ?
&rt_module_self()->module_object[type] : &rt_object_container[type];
#else
/* get object information */
information = &rt_object_container[type];
#endif
object = (struct rt_object *)rt_malloc(information->object_size);//爲對象動態分配內存空間
if (object == RT_NULL)
{
/* no memory can be allocated */
return RT_NULL;
}
/* initialize object's parameters */
/* set object type */
object->type = type;//設置類型
/* set object flag */
object->flag = 0;//設置標誌爲0
#ifdef RT_USING_MODULE
if (rt_module_self() != RT_NULL)
{
object->flag |= RT_OBJECT_FLAG_MODULE;//如果使用了模塊功能,則將flag標誌設置爲模塊標誌
}
object->module_id = (void *)rt_module_self();//設置模塊ID
#endif
/* copy name */
rt_strncpy(object->name, name, RT_NAME_MAX);//給名稱賦值
RT_OBJECT_HOOK_CALL(rt_object_attach_hook, (object));//使用鉤子函數
/* lock interrupt */
temp = rt_hw_interrupt_disable();//關中斷
/* insert object into information object list */
rt_list_insert_after(&(information->object_list), &(object->list));//將此對象加入對應容器
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//關中斷
/* return object */
return object;
}
2.2 脫離或刪除對象
如果對象是靜態初始化的,那麼對應的是脫離,如果是動態初始化的,則是刪除.
脫離接口如下:
/**
* This function will detach a static object from object system,
* and the memory of static object is not freed.
*
* @param object the specified object to be detached.
*/
void rt_object_detach(rt_object_t object)
{
register rt_base_t temp;
/* object check */
RT_ASSERT(object != RT_NULL);
RT_OBJECT_HOOK_CALL(rt_object_detach_hook, (object));//使用鉤子函數
/* lock interrupt */
temp = rt_hw_interrupt_disable();//關中斷
/* remove from old list */
rt_list_remove(&(object->list));//從窗口中移除
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//開中斷
}
刪除接口如下:
/**
* This function will delete an object and release object memory.
*
* @param object the specified object to be deleted.
*/
void rt_object_delete(rt_object_t object)
{
register rt_base_t temp;
/* object check */
RT_ASSERT(object != RT_NULL);
RT_ASSERT(!(object->type & RT_Object_Class_Static));//刪除的對象必須是非系統對象
RT_OBJECT_HOOK_CALL(rt_object_detach_hook, (object));//使用鉤子函數
/* lock interrupt */
temp = rt_hw_interrupt_disable();//關中斷
/* remove from old list */
rt_list_remove(&(object->list));//從對應的容器中移除
/* unlock interrupt */
rt_hw_interrupt_enable(temp);//開中斷
#if defined(RT_USING_MODULE) && defined(RT_USING_SLAB)//如果使用了模塊功能且採用的是SLAB動態內存管理模式
if (object->flag & RT_OBJECT_FLAG_MODULE)
rt_module_free((rt_module_t)object->module_id, object);//釋放模塊ID所佔空間
else
#endif
/* free the memory of object */
rt_free(object);//釋放內核對象所佔空間
}
其中rt_list_remove會自動找到對象的前一節點和後一節點,然後刪除本身節點.
2.3 判斷是否爲系統內核對象
/**
* This function will judge the object is system object or not.
* Normally, the system object is a static object and the type
* of object set to RT_Object_Class_Static.
*
* @param object the specified object to be judged.
*
* @return RT_TRUE if a system object, RT_FALSE for others.
*/
rt_bool_t rt_object_is_systemobject(rt_object_t object)
{
/* object check */
RT_ASSERT(object != RT_NULL);
if (object->type & RT_Object_Class_Static)//RTT是通過內核對象的type的最高位是否爲1來判斷此對象是否爲系統內核對象的
return RT_TRUE;
return RT_FALSE;
}
2.4 查找內核對象
/**
* This function will find specified name object from object
* container.
*
* @param name the specified name of object.
* @param type the type of object
*
* @return the found object or RT_NULL if there is no this object
* in object container.
*
* @note this function shall not be invoked in interrupt status.
*/
rt_object_t rt_object_find(const char *name, rt_uint8_t type)
{
struct rt_object *object;
struct rt_list_node *node;
struct rt_object_information *information;
extern volatile rt_uint8_t rt_interrupt_nest;
/* parameter check *///輸入系統檢查
if ((name == RT_NULL) || (type > RT_Object_Class_Unknown))
return RT_NULL;
/* which is invoke in interrupt status */
if (rt_interrupt_nest != 0)//確保當前沒有中斷嵌套
RT_ASSERT(0);
/* enter critical */
rt_enter_critical();//進入臨界區
/* try to find object */
information = &rt_object_container[type];//獲取對應的對象容器
for (node = information->object_list.next;//開始通過名字來掃描內核對象
node != &(information->object_list);
node = node->next)
{
object = rt_list_entry(node, struct rt_object, list);//獲取內核對象
if (rt_strncmp(object->name, name, RT_NAME_MAX) == 0)//判斷名字是否相符
{
/* leave critical */
rt_exit_critical();//退出臨界區
return object;
}
}
/* leave critical */
rt_exit_critical();//退出臨界區
return RT_NULL;
}
3 內核對象系統初始化
/**
* @ingroup SystemInit
*
* This function will initialize system object management.
*
* @deprecated since 0.3.0, this function does not need to be invoked
* in the system initialization.
*/
void rt_system_object_init(void)
{
}
從源代碼可以看出,自從0.3.0以後,RTT就已經沒有必須再使用此接口來對內核對象初始化了,因此,此函數是空的,但在系統初始化時還會保留調用些函數.
至此,RTT的內核對象系統源碼分析已完!
————————————————
版權聲明：本文爲CSDN博主「flydream0」的原創文章，遵循 CC 4.0 BY-SA 版權協議，轉載請附上原文出處鏈接及本聲明。
原文鏈接：https://blog.csdn.net/flydream0/article/details/8568463