linux 用户态下使用list.h文件中的操作

linux 内核中的库文件里面对双链表的操作的算法都是很经典的
这几天专门阅读了里面的代码。为了加深对代码的理解程度，所以打算在用户态下
对里面的内容进行一些实现
因为我只是初步的测试一下里面的一些操作，所以我创建了一个list.h文件，在里面放入部分的的代码
我的list.h文件的代码如下所示：

/*
 * 下面这些代码都是从文件中复制过来的，
 * 只是复制了一些我下面用到的
 *
 */

#define LIST_POISON1 ((void *) 0x00100100)
#define LIST_POISON2 ((void *) 0x00200200)


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


#define list_entry(ptr, type, member) \
    ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
#define list_for_each_safe(pos, n, head) \
    for (pos = (head)->next, n = pos->next; pos != (head); \
        pos = n, n = pos->next)


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


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;
 }


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


void list_add_tail(struct list_head *new, struct list_head *head)
{
    __list_add(new, head->prev, head);
}

void __list_del(struct list_head * prev,struct list_head * next)
{
    next->prev=prev;
    prev->next=next;
}
void list_del(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
    entry->next = LIST_POISON1;
    entry->prev = LIST_POISON2;
}

下面的test_list.c代码是测试使用list.h中的一些操作

/*
 * description: This program is test how to use
 * the list.h
 *
 * author:chenshuanglin
 * Date:2013/9/17
 */

#include <stdio.h>
#include <stdlib.h>
#include "list.h"
#define N 10 //链表节点数

typedef struct numlist{
    int num; //数据
    struct list_head list; //指向双链表前后结点的指针
}NumNode;

/*
 * author:chenshuanglin
 * description:This function is create a doubleList
 *
 */
void createList(NumNode * head)
{
    int i;
    NumNode * newNode; //每次申请链表结点时所使用的指针
    printf("Please input 10 number: ");
    for(i = 0 ; i < N ; i++)
    {
        newNode = (NumNode *)malloc(sizeof(NumNode));
        scanf("%d",&newNode->num);
        list_add_tail(&newNode->list,&head->list); //调用list.h中的添加节点的函数list_add_tail
    }
}

/*
 * author:chenshuanglin
 * description: Print this doubleList
 */
void printDoubleList(NumNode *head)
{
    int    i=1;
    struct list_head * pos;
    NumNode * num;
    list_for_each(pos,&head->list) //调用list.h中的list_for_each函数进行遍历
    {
        num = list_entry(pos,NumNode,list); //调用list_entry函数得到相对应的节点
        printf("Node %d's data: %d\n", i , num->num);
        i++;
    }
}

/*
 * author:chenshuanglin
 * description: delete number we want
 *
 */
void deleteNum(NumNode * head,int number)
{
    struct list_head *pos,*n;
    NumNode *p;
    int i=1;
    int judge = 0;
    list_for_each_safe(pos,n,&head->list)
    {
        p = list_entry(pos,NumNode,list);
        if(p->num == number)
        {
            judge = 1 ;
            list_del(pos);
            free(p);
            printf("this node %d has removed from the doublelist...\n",i);
        }
        i++;
    }
    if(judge == 0 )
    {
        printf("NO FOUND!\n");
    }

}
/*
 * test Main()
 */
int main(void)
{
    NumNode head;
    int number;
    INIT_LIST_HEAD(&head.list);
    createList(&head);
    printDoubleList(&head);
    printf("Please input the number you want to delete: ");
    scanf("%d",&number);
    deleteNum(&head,number);
    printDoubleList(&head);
    return 1;
}

这个小例子可以方便大家学习list.h中的内容