Linux散列表(二)——宏

我就是我 2022-09-18 15:43 112阅读 0赞

散列表宏承接了双向链表宏的风范，好使好用！务必区分“结点”和“元素”！双链表宏博文中已经提及，这里不赘述！

### 1、获取元素(结构体)基址 ###

#define hlist_entry(ptr, type, member) container_of(ptr,type,member)

#define hlist_entry_safe(ptr, type, member) \
    	({ typeof(ptr) ____ptr = (ptr); \
    	   ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
    	})

第一个不带安全机制，第二个带安全机制，即ptr为NULL时，返回NULL，否则，返回基址！原理 [点击这里查看container\_of  
][container_of]

### 2、操作散列表结点 ###

#### 2.1、遍历散列表结点 ####

#define hlist_for_each(pos, head) \
    	for (pos = (head)->first; pos ; pos = pos->next)

#### 2.2、删除散列表结点 ####

#define hlist_for_each_safe(pos, n, head) \
    	for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
    	     pos = n)

### 3、操作散列表元素 ###

#### 3.1、从head的first开始遍历 ####

/**
     * hlist_for_each_entry	- iterate over list of given type
     * @pos:	the type * to use as a loop cursor.
     * @head:	the head for your list.
     * @member:	the name of the hlist_node within the struct.
     */
    #define hlist_for_each_entry(pos, head, member)				\
    	for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
    	     pos;							\
    	     pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))

#### 3.2、从pos的next开始遍历 ####

/**
     * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
     * @pos:	the type * to use as a loop cursor.
     * @member:	the name of the hlist_node within the struct.
     */
    #define hlist_for_each_entry_continue(pos, member)			\
    	for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
    	     pos;							\
    	     pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))

#### 3.3、从pos开始遍历 ####

/**
     * hlist_for_each_entry_from - iterate over a hlist continuing from current point
     * @pos:	the type * to use as a loop cursor.
     * @member:	the name of the hlist_node within the struct.
     */
    #define hlist_for_each_entry_from(pos, member)				\
    	for (; pos;							\
    	     pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))

#### 3.4、从head的first开始删除 ####

/**
     * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
     * @pos:	the type * to use as a loop cursor.
     * @n:		another &struct hlist_node to use as temporary storage
     * @head:	the head for your list.
     * @member:	the name of the hlist_node within the struct.
     */
    #define hlist_for_each_entry_safe(pos, n, head, member) 		\
    	for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
    	     pos && ({ n = pos->member.next; 1; });			\
    	     pos = hlist_entry_safe(n, typeof(*pos), member))

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[container_of]: http://blog.csdn.net/cwcmcw/article/details/17020139