View source for Listx.h commentato + esempio su container of

==Intro==
Siccome mi e` stato chiesto, per chiunque ne avesse bisogno, qui c'e` il file listx.h con i commenti presi dal file originale list.h, ho aggiunto in piu un esempio su come usare la macro container_of
<source lang="C">
* subset of the Linux Kernel source file: "include/linux/list.h"
CPLv2 */
#ifndef _LISTX_H
#define _LISTX_H

typedef unsigned int    size_t;

/**
* example:
*
* struct container
* {
* 	int some_data;
* 	struct list_head list;
* };
*
* *list_ptr is a pointer to the list member
*
* struct container *container_ptr;
* container_ptr = container_of(list_ptr, struct container, list);
*/
#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)

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!
 */
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);
}
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;
}
static inline struct list_head *list_next(const struct list_head *current)
{
	if (list_empty(current))
		return NULL;
	else
		return current->next;
}
static inline struct list_head *list_prev(const struct list_head *current)
{
	if (list_empty(current))
		return NULL;
	else
		return current->prev;
}
/**
 * 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_prev	-	iterate over a list backwards
 * @pos:	the &struct list_head to use as a loop counter.
 * @head:	the head for your list.
 */
#define list_for_each_prev(pos, head) \
	for (pos = (head)->prev; pos != (head); pos = pos->prev)
/**
 * 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.
 */
#define list_for_each_entry(pos, head, member)                          \
	for (pos = container_of((head)->next, typeof(*pos), member);      \
	&pos->member != (head);        \
	pos = container_of(pos->member.next, typeof(*pos), member))

#define list_for_each_entry_reverse(pos, head, member)                  \
	for (pos = container_of((head)->prev, typeof(*pos), member);      \
	&pos->member != (head);        \
	pos = container_of(pos->member.prev, typeof(*pos), member))

#endif
</source>
[[User:Eddy|Eddy]] ([[User talk:Eddy|talk]]) 12.20 FRI, 30 Gen 2014 (CET)