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double_linked_list.h
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double_linked_list.h
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/**
* A linux kernel like implementation of double linked list.
*/
#ifndef _DOUBLE_LINKED_LIST_H_
#define _DOUBLE_LINKED_LIST_H_
struct list_head {
struct list_head * next;
struct list_head * prev;
};
/**
* Following two macros are for initializing an empty list.
*/
#define LIST_HEAD_INIT(name) { &(name), &(name) }
#define LIST_HEAD(name) \
struct list_head name = LIST_HEAD(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 for internal use only as we know consecutive list entries
* and where we want to insert the newNode between prevNode and
* nextNode in list
*/
static inline void __list_add( struct list_head *newNode,
struct list_head *prevNode,
struct list_head *nextNode)
{
prevNode->next = newNode;
newNode->prev = prevNode;
newNode->next = nextNode;
nextNode->prev = newNode;
}
/**
* list_add - Add a new entry
* @param newNode [new entry to be added in list]
* @param head [list head to add it after]
* @return [none]
* Insert a new entry after specified head
* This is good for implementation of a stack
*/
static inline void list_add( struct list_head * newNode,
struct list_head * head)
{
__list_add( newNode, head, head->next );
}
/**
* list_add_tail [Add a new entry to the tail]
* @param newNode [new entry to be added]
* @param head [list add to add it before]
*
* Insert a new entry before specified head
* This is good for implementation of queue.
*/
static inline void list_add_tail( struct list_head * newNode,
struct list_head * head)
{
__list_add( newNode, head->prev, head );
}
/**
* Delete an entry between prevNode and nextNode by making prevNode/nextNode
* pointing to each other
* This is only used for internal list manipulation when we
* know prevNode/nextNode entries already
*/
static inline void __list_del( struct list_head * prevNode,
struct list_head * nextNode)
{
prevNode->next = nextNode;
nextNode->prev = prevNode;
}
/**
* Deletes an entry from the list
* @param entry [Entry to be deleted]
*/
static inline void list_del( struct list_head * entry )
{
__list_del(entry->prev, entry->next);
entry->prev = nullptr;
entry->next = nullptr;
}
static inline void __list_del_entry( struct list_head * entry) {
__list_del( entry->prev, entry->next );
}
/**
* Replace @oldNode with @newNode in the list
* @param oldNode [Node to be replaced]
* @param newNode [This node replaces the oldNode]
*/
static inline void list_replace( struct list_head * oldNode,
struct list_head * newNode)
{
newNode->next = oldNode->next;
newNode->prev = oldNode->prev;
oldNode->prev->next = newNode;
oldNode->next->prev = newNode;
}
static inline void list_replace_init( struct list_head * oldList,
struct list_head * newList)
{
list_replace( oldList, newList );
INIT_LIST_HEAD( oldList );
}
/**
* Deletes the entry from the list and reinitialize it
* @param entry [node to be deleted and reinitialized]
*/
static inline void list_del_init( struct list_head * entry )
{
__list_del( entry->prev, entry->next );
INIT_LIST_HEAD( entry );
}
/**
* list_move - deletes from one list and adds as another's head
* @param list [the entry to move]
* @param head [the head that will precede our entry]
*/
static inline void list_move( struct list_head * list,
struct list_head * head)
{
__list_del_entry( list );
list_add( list, head );
}
/**
* list_move_tail- deletes from one list and adds as another's tail
* @param list [the entry to move]
* @param head [the head that will follow our entry]
*/
static inline void list_move_tail( struct list_head * list,
struct list_head * head)
{
__list_del_entry( list );
list_add_tail( list, head );
}
/**
* list_is_last - Determines if @entry node is the last in the list
* @param entry [Node to be checked if it is last]
* @param head [the head of the list]
* @return [ true if entry is last false otherwise]
*/
static inline bool list_is_last( const struct list_head * entry,
const struct list_head * head )
{
return ( entry->next == head );
}
/**
* list_is_empty - Verifies if the list is empty
* @param head [the list to be tested`
* @return - returns true if list is empty, otherwise false
*/
static inline bool list_is_empty( const struct list_head * head )
{
return ( head->next == head );
}
/**
* list_is_empty_careful - tests whether list is empty and not being modified i.e.
* checks that no other cpu is in process of modifying next or prev
* @param head [the list to be tested]
* @return [returns true if list is empty and not being modified]
*/
static inline bool list_is_empty_careful( const struct list_head * head)
{
struct list_head * nextNode = head->next;
return ( nextNode == head ) && ( nextNode == head->prev );
}
/**
* list_rotate_left - Rotate the list to left (1,2,3,4)-->(2,3,4,1)
* @param head head of the list
*/
static inline void list_rotate_left( struct list_head * head )
{
struct list_head * first;
if ( !list_is_empty(head) ) {
first = head->next;
list_move_tail( first, head );
}
}
/**
* [list_is_singular - check if list contain just one entry
* @param head [head of the list]
* @return [return true if list has just one entry false otherwise]
*/
static inline bool list_is_singular( const struct list_head * head)
{
return (!list_is_empty(head) && ( head->next == head->prev ));
}
/**
* Internal function to join two list at position between prev and next
* @param list [new list]
* @param prev [new list to be added after this]
* @param next [new list to be added before this]
*/
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
* @param list [The new list to be added]
* @param head [The entry where you want to add the new list in current list]
*/
static inline void list_splice( const struct list_head * list,
struct list_head * head )
{
if( !list_is_empty(list) ) {
__list_splice(list, head, head->next);
}
}
/**
* list_splice_init : join two lists and reinitialise the emptied list.
* @param list [The new list to be adeed]
* @param head [The entry where you want to add the new list in current list]
*/
static inline void list_splice_init( struct list_head * list,
struct list_head * head)
{
if( !list_is_empty(list) ) {
__list_splice(list, head, head->next);
INIT_LIST_HEAD(list);
}
}
/**
* list_entry - get the struct for this entry
* @param ptr [the &struct list_head pointer]
* @param ptrtype [the pointer to the type of struct this was embedded in]
* @param member [the name of the list_struct within the struct.]
*/
#define list_entry(ptr, ptrtype, member) \
(reinterpret_cast<ptrtype>( (char *)(ptr) - (char *)(&(reinterpret_cast<ptrtype>(1)->member)) + 1))
/**
* [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_prev] -- Iterate over a list in reverse
* @param pos [the &struct list_head to use as a loop counter.]
* @param 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_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.
*/
#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 a list of given type
* @param pos [The pointer to use as loop counter]
* @param head [The head of your list]
* @param member [the name of the list_struct within the struct.]
*/
#define list_for_each_entry(pos, head, member) \
for (pos = list_entry((head)->next, decltype(pos), member); \
&pos->member != (head); \
pos = list_entry(pos->member.next, decltype(pos), member))
/**
* Move a node to the front
*/
static inline void list_mtf(struct list_head *entry, struct list_head *head) {
if (entry->prev == head) return;
__list_del(entry->prev, entry->next);
__list_add(entry, head, head->next);
}
/**
* Move a node ahead one position
*/
static inline void list_mao(struct list_head *entry, struct list_head * head) {
// if the entry in the 1st position
if (entry->prev == head) return;
struct list_head * prev = entry->prev;
__list_del(entry->prev, entry->next);
__list_add(entry, prev->prev, prev);
}
#endif