1.内核头文件
#ifndef __DLIST_H
#define __DLIST_H
/* This file is from Linux Kernel (include/linux/list.h)
* and modified by simply removing hardware prefetching of list items.
* Here by copyright, credits attributed to wherever they belong.
* Kulesh Shanmugasundaram (kulesh [squiggly] isis.poly.edu)
*/
/*
* Simple doubly linked list implementation.
*
* Some of the internal functions (“__xxx”) are useful when
* manipulating whole lists rather than single entries, as
* sometimes we already know the next/prev entries and we can
* generate better code by using them directly rather than
* using the generic single-entry routines.
*/
/**
* 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 offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - 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;
};
#define LIST_HEAD_INIT(name) { &(name), &(name) }
//定义一个节点，并将两个指针域自己指向自己
#define LIST_HEAD(name) \
struct list_head name = LIST_HEAD_INIT(name)
//将传入的ptr指向的节点的两个指针域自己指向自己
#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!
*/
//将节点new插入到节点prev和next之间
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.
*/
//将new节点插入到一个链表头结点head的后边（头插入）
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.
*/
//将new节点插入到一个链表头结点head的前边（尾插入）
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!
*/
//删除节点prev和next之间的节点
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.
*/
//删除节点entry，并将entry的两个指针域设为NULL;
static inline void list_del(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
entry->next = (void *) 0;
entry->prev = (void *) 0;
}
/**
* list_del_init – deletes entry from list and reinitialize it.
* @entry: the element to delete from the list.
*/
//删除节点entry，并将entry的两个指针域自己指向自己;
static inline void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
INIT_LIST_HEAD(entry);
}
/**
* list_move – delete from one list and add as another’s head
* @list: the entry to move
* @head: the head that will precede our entry
*/
//删除list节点，并将list节点插入到head头结点的后边
static inline void list_move(struct list_head *list,
struct list_head *head)
{
__list_del(list->prev, list->next);
list_add(list, head);
}
/**
* list_move_tail – delete from one list and add as another’s tail
* @list: the entry to move
* @head: the head that will follow our entry
*/
//删除list节点，并将list节点插入到head头结点的前边
static inline void list_move_tail(struct list_head *list,
struct list_head *head)
{
__list_del(list->prev, list->next);
list_add_tail(list, head);
}
/**
* list_empty – tests whether a list is empty
* @head: the list to test.
*/
//判断内核链表是否为空
static inline int list_empty(struct list_head *head)
{
return head->next == head;
}
//将头结点为list和头结点为head的两个链表进行合并，舍弃list头节点
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);
}
/**
* list_splice_init – join two lists and reinitialise the emptied list.
* @list: the new list to add.
* @head: the place to add it in the first list.
*
* The list at @list is reinitialised
*/
//将头结点为list和头结点为head的两个链表进行合并，舍弃list头节点
//并将list头结点的指针域自己指向自己
static inline void list_splice_init(struct list_head *list,
struct list_head *head)
{
if (!list_empty(list)) {
__list_splice(list, head);
INIT_LIST_HEAD(list);
}
}
/**
* 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.
*/
//ptr:指向小结构体的指针
//type:大结构体的类型
//member:小结构体的变量成员
/*
struct test{
int data;
struct list_head member;
}typedef type struct test;
*/
//通过小结构体来获得大结构体的数据
//小结构体的实际地址 - 小结构体相对于大结构体的偏移量
//宏的返回值：大结构体的实际地址。
#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.
*/
//对小结构体的遍历，从前向后
//pos是指向小结构体的遍历指针，head为小结构体头结点
#define list_for_each(pos, head) \
for (pos = (head)->next; pos != (head); \
pos = pos->next)
/**
* list_for_each_prev - iterate over a list backwards
* @pos: the &struct list_head to use as a loop counter.
* @head: the head for your list.
*/
//对小结构体的遍历，从后向前
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev; pos != (head); \
pos = pos->prev)
/**
* list_for_each_safe - iterate over a list safe against removal of list entry
* @pos: the &struct list_head to use as a loop counter.
* @n: another &struct list_head to use as temporary storage
* @head: the head for your list.
*/
//对小结构体的遍历,当遍历当前节点时，记住下一个节点，防止断链。
#define list_for_each_safe(pos, n, head) \
for (pos = (head)->next, n = pos->next; pos != (head); \
pos = n, n = pos->next)
/**
* list_for_each_entry - iterate over list of given type
* @pos: the type * to use as a loop counter.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*/
//通过小结构体来实现对大结构体的遍历
//pos：大结构体的指针
//head:小结构体头结点
//member:小结构体的变量
#define list_for_each_entry(pos, head, member) \
for (pos = list_entry((head)->next, typeof(*pos), member); \
&pos->member != (head); \
pos = list_entry(pos->member.next, typeof(*pos), member))
/**
* list_for_each_entry_safe – iterate over list of given type safe against removal of list entry
* @pos: the type * to use as a loop counter.
* @n: another type * to use as temporary storage
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*/
//通过小结构体来实现对大结构体的遍历，当遍历当前节点时，记住下一个节点，防止断链。
#define list_for_each_entry_safe(pos, n, head, member) \
for (pos = list_entry((head)->next, typeof(*pos), member), \
n = list_entry(pos->member.next, typeof(*pos), member); \
&pos->member != (head); \
pos = n, n = list_entry(n->member.next, typeof(*n), member))
#endif
2.演示Demo
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "dlist.h"
typedef struct node{
int data;
struct list_head member;
}linknode,*plink;
int main()
{
plink p;
int a;
struct list_head *tmp;
plink pos;
//1.初始化
LIST_HEAD(head);
scanf("%d",&a);
while(a != -1){
//2.分配空间
p = (plink)malloc(sizeof(linknode));
if(NULL == p){
printf("malloc error\n");
exit(1);
}
p->data = a;
//3.头插入
list_add_tail(&p->member,&head);
scanf("%d",&a);
}
//4.遍历
#if 0
list_for_each(tmp,&head){
pos = list_entry(tmp,struct node,member);
printf("%d\t",pos->data);
}
printf("\n");
#else
list_for_each_entry(pos, &head, member){
printf("%d\t", pos->data);
}
printf("\n");
#endif
return 0;
}