一个统一的链表结构

王朝other·作者佚名  2006-01-08
窄屏简体版  字體: |||超大  

这是在Linux下面最常用的一个统一的链表结构,Linux就是用这个结构将所有的Driver、Device什么的都分别串在一起。我觉得写得非常好,大家来看一看。

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#ifndef _LINUX_LIST_H

#define _LINUX_LIST_H

#ifdef __KERNEL__

struct list_head {

struct list_head *next, *prev;

};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name) struct list_head name = LIST_HEAD_INIT(name)

#define INIT_LIST_HEAD(ptr) do { (ptr)->next = (ptr); (ptr)->prev = (ptr); } while (0)

/*

* Insert a new entry between two known consecutive entries.

* This is only for internal list manipulation where we know the prev/next entries already!

*/

static __inline__ void __list_add(struct list_head * new, struct list_head * prev, struct list_head * next)

{

next->prev = new;

new->next = next;

new->prev = prev;

prev->next = new;

}

/*

* list_add - add a new entry

* Insert a new entry after the specified head.

* This is good for implementing stacks.

*/

static __inline__ void list_add(struct list_head *new, struct list_head *head)

{

__list_add(new, head, head->next);

}

/*

* list_add_tail - add a new entry

* Insert a new entry before the specified head.

* This is useful for implementing queues.

*/

static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)

{

__list_add(new, head->prev, head);

}

/*

* Delete a list entry by making the prev/next entries point to each other.

* This is only for internal list manipulation where we know the prev/next entries already!

*/

static __inline__ void __list_del(struct list_head * prev, struct list_head * next)

{

next->prev = prev;

prev->next = next;

}

/*

* list_del - deletes entry from list.

* Note: list_empty on entry does not return true after this, the entry is in an undefined state.

*/

static __inline__ void list_del(struct list_head *entry)

{

__list_del(entry->prev, entry->next);

}

/**

* list_del_init - deletes entry from list and reinitialize it.

*/

static __inline__ void list_del_init(struct list_head *entry)

{

__list_del(entry->prev, entry->next);

INIT_LIST_HEAD(entry);

}

/*

* list_empty - tests whether a list is empty

*/

static __inline__ int list_empty(struct list_head *head)

{

return head->next == head;

}

/**

* list_splice - join two lists

* @list: the new list to add.

* @head: the place to add it in the first list.

*/

static __inline__ void list_splice(struct list_head *list, struct list_head *head)

{

struct list_head *first = list->next;

if (first != list) {

struct list_head *last = list->prev;

struct list_head *at = head->next;

first->prev = head;

head->next = first;

last->next = at;

at->prev = last;

}

}

/**

* list_entry - get the struct for this entry

* @ptr: the &struct list_head pointer.

* @type: the type of the struct this is embedded in.

* @member: the name of the list_struct within the struct.

*/

#define list_entry(ptr, type, member) ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**

* list_for_each - iterate over a list

* @pos: the &struct list_head to use as a loop counter.

* @head: the head for your list.

*/

#define list_for_each(pos, head) for (pos = (head)->next; pos != (head); pos = pos->next)

#endif /* __KERNEL__ */

#endif

补充一下——给看不懂的同志。

它是个双向的循环链表,这个链表可以用到任何结构里,比如:

struct kk {

type1 data1;

type2 data2;

......

struct list_head list;

typen datan;

}

再有一个链表头:LIST_HEAD(kk_list)

然后调用链表函数的时候是这样的,比如要把一个新结点kk_node加到链表尾

list_add_tail ( &(kk_node.list), &kk_list );

只是把结点中的list成员加进去,要获得某个包含list_head节点的结构指针

struct kk *p = list_entry( p, kk, list );

当调用delete操作时,仅仅是把结点从链表中去掉,并不真正释放结点所占用的空间,因为这是个通用结构嘛,分配释放由用户自己管理。

 
 
 
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