玩转C链表

#ifndef __C_LIST_H
#define  __C_LIST_H

typedef unsigned  char  u8;
typedef unsigned  short  u16;
typedef unsigned  int  u32;
typedef unsigned  long  size_t;

#define  offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

/* *
* container_of - cast a member of a structure out to the containing structure
* @ptr: the pointer to the member.
* @type: the type of the container struct this is embedded in.
* @member: the name of the member within the struct.
*
*/
#define  container_of(ptr, type, member) (type *)((char *)ptr -offsetof(type,member))

/*
* These are non-NULL pointers that will result in page faults
* under normal circumstances, used to verify that nobody uses
* non-initialized list entries.
*/
#define  LIST_POISON1 ((void *) 0x00100100)
#define  LIST_POISON2 ((void *) 0x00200200)

struct  list_head {
struct  list_head  * next,  * prev;
};

/* *
* 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) \
container_of(ptr, type, member)


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

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

static  inline  void  INIT_LIST_HEAD( struct  list_head  * list)
{
list -> next  =  list;
list -> prev  =  list;
}

/* *
* 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)

/* *
* list_for_each_r - iterate over a list reversely
* @pos: the &struct list_head to use as a loop counter.
* @head: the head for your list.
*/
#define  list_for_each_r(pos, head) \
for  (pos  =  (head) -> prev; pos  !=  (head); pos  =  pos -> prev) 

/*
* 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
* @new: new entry to be added
* @head: list head to add it after
*
* 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
* @new: new entry to be added
* @head: list head to add it before
*
* 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.
* @entry: the element to delete from the 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);
entry -> next  =  LIST_POISON1;
entry -> prev  =  LIST_POISON2;
}


/* *
* list_empty - tests whether a list is empty
* @head: the list to test.
*/
static  inline  int  list_empty( const   struct  list_head  * head)
{
return  head -> next  ==  head;
}


static  inline  void  __list_splice( struct  list_head  * list,
struct  list_head  * head)
{
struct  list_head  * first  =  list -> next;
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_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)
{
if  ( ! list_empty(list))
__list_splice(list, head);
}


#endif   //  __C_LIST_H