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/**
* @file op_list.h
* Kernel-style lists
*
* @remark Copyright 2002 OProfile authors
* @remark Read the file COPYING
*
* @author Linux kernel authors
*/

#ifndef OP_LIST_H
#define OP_LIST_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;
};

/**
* list_init - init a new entry
* @param ptr the list to init
*
* Init a list head to create an empty list from it
*/
static __inline__ void list_init(struct list_head * ptr)
{
ptr->next = ptr;
ptr->prev = ptr;
}

/*
* 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_entry,
struct list_head * prev,
struct list_head * next)
{
next->prev = new_entry;
new_entry->next = next;
new_entry->prev = prev;
prev->next = new_entry;
}

/**
* list_add - add a new entry
* @param new new entry to be added
* @param 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_entry, struct list_head * head)
{
__list_add(new_entry, head, head->next);
}

/**
* list_add_tail - add a new entry
* @param new new entry to be added
* @param 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_entry, struct list_head * head)
{
__list_add(new_entry, 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.
* @param 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);
}

/**
* list_del_init - deletes entry from list and reinitialize it.
* @param entry the element to delete from the list.
*/
static __inline__ void list_del_init(struct list_head * entry)
{
__list_del(entry->prev, entry->next);
list_init(entry);
}

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

/**
* list_splice - join two lists
* @param list the new list to add.
* @param head the place to add it in the first list.
*/
static __inline__ void list_splice(struct list_head * list, struct list_head * head)
{
struct list_head * first = list->next;

if (first != list) {
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_entry - get the struct for this entry
* @param ptr the &struct list_head pointer.
* @param type the type of the struct this is embedded in.
* @param member the name of the list_struct within the struct.
*/
#define list_entry(ptr, type, member) \
((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

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

/**
* list_for_each_safe - iterate over a list safe against removal of list entry
* @param pos the &struct list_head to use as a loop counter.
* @param n another &struct list_head to use as temporary storage
* @param 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)

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

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

#endif /* OP_LIST_H */
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