lish.h定义双向循环链表的的相关操作。具体的源码分析网上有很多,而且你自己通过阅读注释也可以看懂每个函数的具体功能。接下来就是list.h文件的运用:
由于list.h属于内核模块中的库文件(usr\src\linux-headers-version\include\linux\
而默认加载的是usr\include\下的库文件,不包含list.h
因此需要自己写一个库文件其中包含list.h中的函数
mylist.h
#ifndef _LINUX_LIST_H #define _LINUX_LIST_H #include <linux/stddef.h> /* * 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. */ 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) static inline void INIT_LIST_HEAD(struct list_head *list) { list->next = list; list->prev = list; } /* * Insert a new entry between two known consecutive entries. * * This is only for internal list manipulation where we know * the prev/next entries already! */ #ifndef CONFIG_DEBUG_LIST 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; } #else extern void __list_add(struct list_head *new, struct list_head *prev, struct list_head *next); #endif /** * 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. */ #ifndef CONFIG_DEBUG_LIST static inline void list_del(struct list_head *entry) { __list_del(entry->prev, entry->next); INIT_LIST_HEAD(entry); } #else extern void list_del(struct list_head *entry); #endif /** * list_replace - replace old entry by new one * @old : the element to be replaced * @new : the new element to insert * * If @old was empty, it will be overwritten. */ static inline void list_replace(struct list_head *old, struct list_head *new) { new->next = old->next; new->next->prev = new; new->prev = old->prev; new->prev->next = new; } static inline void list_replace_init(struct list_head *old, struct list_head *new) { list_replace(old, new); INIT_LIST_HEAD(old); } /** * list_del_init - deletes entry from list and reinitialize it. * @entry: the element to delete from the list. */ 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 */ 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 */ 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_is_last - tests whether @list is the last entry in list @head * @list: the entry to test * @head: the head of the list */ static inline int list_is_last(const struct list_head *list, const struct list_head *head) { return list->next == head; } /** * 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; } /** * list_empty_careful - tests whether a list is empty and not being modified * @head: the list to test * * Description: * tests whether a list is empty _and_ checks that no other CPU might be * in the process of modifying either member (next or prev) * * NOTE: using list_empty_careful() without synchronization * can only be safe if the only activity that can happen * to the list entry is list_del_init(). Eg. it cannot be used * if another CPU could re-list_add() it. */ static inline int list_empty_careful(const struct list_head *head) { struct list_head *next = head->next; return (next == head) && (next == head->prev); } /** * list_is_singular - tests whether a list has just one entry. * @head: the list to test. */ static inline int list_is_singular(const struct list_head *head) { return !list_empty(head) && (head->next == head->prev); } static inline void __list_cut_position(struct list_head *list, struct list_head *head, struct list_head *entry) { struct list_head *new_first = entry->next; list->next = head->next; list->next->prev = list; list->prev = entry; entry->next = list; head->next = new_first; new_first->prev = head; } /** * list_cut_position - cut a list into two * @list: a new list to add all removed entries * @head: a list with entries * @entry: an entry within head, could be the head itself * and if so we won't cut the list * * This helper moves the initial part of @head, up to and * including @entry, from @head to @list. You should * pass on @entry an element you know is on @head. @list * should be an empty list or a list you do not care about * losing its data. * */ static inline void list_cut_position(struct list_head *list, struct list_head *head, struct list_head *entry) { if (list_empty(head)) return; if (list_is_singular(head) && (head->next != entry && head != entry)) return; if (entry == head) INIT_LIST_HEAD(list); else __list_cut_position(list, head, entry); } static inline void __list_splice(const struct list_head *list, struct list_head *prev, struct list_head *next) { struct list_head *first = list->next; struct list_head *last = list->prev; first->prev = prev; prev->next = first; last->next = next; next->prev = last; } /** * list_splice - join two lists, this is designed for stacks * @list: the new list to add. * @head: the place to add it in the first list. */ static inline void list_splice(const struct list_head *list, struct list_head *head) { if (!list_empty(list)) __list_splice(list, head, head->next); } /** * list_splice_tail - join two lists, each list being a queue * @list: the new list to add. * @head: the place to add it in the first list. */ static inline void list_splice_tail(struct list_head *list, struct list_head *head) { if (!list_empty(list)) __list_splice(list, head->prev, 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 */ static inline void list_splice_init(struct list_head *list, struct list_head *head) { if (!list_empty(list)) { __list_splice(list, head, head->next); INIT_LIST_HEAD(list); } } /** * list_splice_tail_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. * * Each of the lists is a queue. * The list at @list is reinitialised */ static inline void list_splice_tail_init(struct list_head *list, struct list_head *head) { if (!list_empty(list)) { __list_splice(list, head->prev, 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. */ #define list_entry(ptr, type, member) \ container_of(ptr, type, member) #define container_of(ptr,type,member) ({ \ const typeof( ((type *)0)->member ) *__mptr = (ptr) ; \ (type *)( (char *) __mptr - offsetof(type,member) ) ;}) #define offsetof(type,member) \ ((size_t) &((type *)0)->member) /** * list_first_entry - get the first element from a list * @ptr: the list head to take the element from. * @type: the type of the struct this is embedded in. * @member: the name of the list_struct within the struct. * * Note, that list is expected to be not empty. */ #define list_first_entry(ptr, type, member) \ list_entry((ptr)->next, type, member) /** * list_for_each - iterate over a list * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. */ /** * __list_for_each - iterate over a list * @pos: the &struct list_head to use as a loop cursor. * @head: the head for your list. * * This variant differs from list_for_each() in that it's the * simplest possible list iteration code, no prefetching is done. * Use this for code that knows the list to be very short (empty * or 1 entry) most of the time. */ #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 cursor. * @head: the head for your list. */ /** * list_for_each_safe - iterate over a list safe against removal of list entry * @pos: the &struct list_head to use as a loop cursor. * @n: another &struct list_head to use as temporary storage * @head: the head for your list. */ #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_prev_safe - iterate over a list backwards safe against removal of list entry * @pos: the &struct list_head to use as a loop cursor. * @n: another &struct list_head to use as temporary storage * @head: the head for your list. */ /** * list_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 list_struct within the struct. */ /** * list_for_each_entry_reverse - iterate backwards 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 list_struct within the struct. */ /** * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() * @pos: the type * to use as a start point * @head: the head of the list * @member: the name of the list_struct within the struct. * * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). */ #define list_prepare_entry(pos, head, member) \ ((pos) ? : list_entry(head, typeof(*pos), member)) /** * list_for_each_entry_continue - continue iteration 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 list_struct within the struct. * * Continue to iterate over list of given type, continuing after * the current position. */ /** * list_for_each_entry_continue_reverse - iterate backwards from the given point * @pos: the type * to use as a loop cursor. * @head: the head for your list. * @member: the name of the list_struct within the struct. * * Start to iterate over list of given type backwards, continuing after * the current position. */ /** * 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 cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_struct within the struct. */ #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)) /** * list_for_each_entry_safe_continue * @pos: the type * to use as a loop cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_struct within the struct. * * Iterate over list of given type, continuing after current point, * safe against removal of list entry. */ #define list_for_each_entry_safe_continue(pos, n, head, member) \ for (pos = list_entry(pos->member.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)) /** * list_for_each_entry_safe_from * @pos: the type * to use as a loop cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_struct within the struct. * * Iterate over list of given type from current point, safe against * removal of list entry. */ #define list_for_each_entry_safe_from(pos, n, head, member) \ for (n = list_entry(pos->member.next, typeof(*pos), member); \ &pos->member != (head); \ pos = n, n = list_entry(n->member.next, typeof(*n), member)) /** * list_for_each_entry_safe_reverse * @pos: the type * to use as a loop cursor. * @n: another type * to use as temporary storage * @head: the head for your list. * @member: the name of the list_struct within the struct. * * Iterate backwards over list of given type, safe against removal * of list entry. */ #define list_for_each_entry_safe_reverse(pos, n, head, member) \ for (pos = list_entry((head)->prev, typeof(*pos), member), \ n = list_entry(pos->member.prev, typeof(*pos), member); \ &pos->member != (head); \ pos = n, n = list_entry(n->member.prev, typeof(*n), member)) /* * Double linked lists with a single pointer list head. * Mostly useful for hash tables where the two pointer list head is * too wasteful. * You lose the ability to access the tail in O(1). */ #endif
list.c
#include <stdio.h> #include <stdlib.h> #include "mylist.h" struct Data { char data; struct list_head list; }; typedef struct Data mydata; void decimal_to_binary(); void binary_to_decimal(); void free_memory(struct list_head *pos,struct list_head *p,struct Data mylist,struct Data *tmp); int main(int argc ,char *argv[]) { int select = 0; printf("**************************************************************\n"); printf("** 1.Decimal to binary **\n"); printf("** 2.Binary to decimal **\n"); printf("** 0.Exit **\n"); printf("**************************************************************\n"); printf("Please select which you want to convert:"); scanf("%d",&select); getchar(); switch (select){ case 0:printf("Welcome to use next time!\n");break; case 1:decimal_to_binary(); break ; case 2:binary_to_decimal(); break; default:printf("Your select is not right!"); break; } return 0; } /*********************************************************************** *Function name:dec_to_binary *Function Description: The function is used to covert a number from * decimal to binary *Parameter:@num ,the decimal which will be coverted *Result:Display the num 's binary result ***********************************************************************/ void decimal_to_binary() { long number,temp; mydata mylist,*tmp; struct list_head *pos,*p; INIT_LIST_HEAD(&mylist.list); printf("please input a number you want to convert:"); scanf("%ld",&number); printf("Decemal number %ld's binary is:",number); if (number == 0) { printf("%ld",number); printf("\n"); return; } while (number != 0) { tmp = (mydata *)malloc(sizeof(mydata)); temp = number % 2; tmp -> data = temp; list_add(&(tmp->list),&(mylist.list)); number = number / 2; } __list_for_each(pos,&mylist.list) { tmp = list_entry(pos,struct Data,list); printf("%ld",(long)tmp->data); } printf("\n"); list_for_each_safe(pos,p,&mylist.list){ tmp = list_entry(pos,struct Data,list); list_del(pos); free(tmp); } if (list_empty(&mylist.list)){ printf("The list now is empty!\n"); } } /*********************************************************************** *Function name:dec_to_binary *Function Description: The function is used to covert a number from * binary to decimal *Parameter:void *Result:Display the num 's decimal result ***********************************************************************/ void binary_to_decimal() { mydata mylist,*tmp; struct list_head *pos,*p; char ch = '0'; long dec = 1; long dec_number = 0; INIT_LIST_HEAD(&mylist.list); printf("Please input the binary number you want to convert:"); ch = getchar(); while ((ch == '0')||(ch == '1')){ tmp = (struct Data *)malloc(sizeof(struct Data)); tmp -> data = ch; list_add(&(tmp->list),&(mylist.list)); ch = getchar(); } __list_for_each(pos,&mylist.list){ tmp = list_entry(pos,struct Data,list); dec_number += (int)(tmp ->data - '0') * dec; dec *= 2; } printf("\n"); printf("Decimal number is %ld\n",dec_number); list_for_each_safe(pos,p,&mylist.list){ tmp = list_entry(pos,struct Data,list); list_del(pos); free(tmp); } if (list_empty(&mylist.list)){ printf("The list now is empty!\n"); } }
listTest.c
#include<stdio.h> #include<stdlib.h> #include"mylist.h" #include<string.h> struct userinfo{ char username[20]; char password[20]; struct list_head list; }; typedef struct userinfo UserStruct; int main(int argc,char *argv[]){ char username[20],password[20]; char flag[2]="#"; UserStruct userlist,*user,*temp,*replacetest,*templist; struct list_head *pos,*p; //初始化双向循环链表 INIT_LIST_HEAD(&(userlist.list)); INIT_LIST_HEAD(&(templist->list)); printf("please input your username and password:\n"); scanf("%s",username); scanf("%s",password); getchar(); //循环添加元素 while(strcmp(username,flag) && strcmp(password,flag)){ user=(struct userinfo*)malloc(sizeof(struct userinfo)); strcpy(user->username,username); strcpy(user->password,password); list_add_tail(&(user->list),&(userlist.list)); printf("please input your username and password:\n"); scanf("%s",username); scanf("%s",password); getchar(); } //利用一个新的节点替换第一个节点 replacetest=(struct userinfo*)malloc(sizeof(struct userinfo)); strcpy(replacetest->username,"username"); strcpy(replacetest->password,"password"); list_replace_init(userlist.list.next,&(replacetest->list)); //将一个节点移动到双向循环链表末尾 list_move_tail(userlist.list.next,&(userlist.list)); //将一个节点移动到双向循环链表头 list_move_tail(userlist.list.prev,&(userlist.list)); if(list_is_last(&(replacetest->list),&(userlist.list))){ printf("该节点是双向循环链表的最后一个节点\n"); } if(!list_is_singular(&(userlist.list))){ printf("该双向循环链表有多个节点\n"); } //遍历双向循环链表 printf("遍历双向循环链表\n"); __list_for_each(pos,&(userlist.list)){ temp=list_entry(pos,struct userinfo,list); printf("用户名:%s 密码:%s\n",temp->username,temp->password); } /* //双向循环链表的切割 list_cut_position(&(templist->list),&(userlist.list),userlist.list.next); //遍历切割的双向循环链表 printf("遍历切割的双向循环链表\n"); __list_for_each(pos,&(templist->list)){ temp=list_entry(pos,struct userinfo,list); printf("用户名:%s 密码:%s\n",temp->username,temp->password); } //合并链表 __list_splice(&(templist->list),userlist.list.next,userlist.list.next->next); list_splice_init(&(templist->list),&(userlist.list)); //遍历合并后双向循环链表 printf("遍历合并后双向循环链表\n"); __list_for_each(pos,&(userlist.list)){ temp=list_entry(pos,struct userinfo,list); printf("用户名:%s 密码:%s\n",temp->username,temp->password); } */ //释放内存资源 list_for_each_safe(pos,p,&(userlist.list)){ temp=list_entry(pos,struct userinfo,list); list_del(pos); free(temp); } if(list_empty(&(userlist.list))){ printf("双向循环链表为空\n"); } return 0; }