util/lists.h

   1 /* $Id: lists.h,v 1.41 2004/07/14 00:24:24 jonas Exp $ */
   2
   3 #ifndef EL__UTIL_LISTS_H
   4 #define EL__UTIL_LISTS_H
   5
   6 /*
   7  * 'Hoo now!' replied Treebeard. 'Hoo! Now that would be telling! Not so hasty.
   8  * And *I* am doing the asking. You are in *my* country. What are *you*,
   9  * I wonder? I cannot place you. You do not seem to come in the old lists that
  10  * I learned when I was young. But that was a long, long time ago, and they may
  11  * have made new lists. Let me see! Let me see! How did it go?
  12  */
  13
  14 #include <stddef.h>
  15
  16 #include <libhed/types.h>
  17
  18 /* Fix namespace clash with system headers (like FreeBSD's, all hail BSD!). */
  19 #undef LIST_HEAD
  20 #undef list_head
  21 #define list_head hed_list_head
  22
  23 /*
  24  * Simple doubly linked list implementation.
  25  *
  26  * Some of the internal functions ("__xxx") are useful when
  27  * manipulating whole lists rather than single entries, as
  28  * sometimes we already know the next/prev entries and we can
  29  * generate better code by using them directly rather than
  30  * using the generic single-entry routines.
  31  */
  32
  33 #define LIST_HEAD_INIT(name) { &(name), &(name) }
  34
  35 #define LIST_HEAD(name) \
  36         struct list_head name = LIST_HEAD_INIT(name)
  37
  38 static inline void INIT_LIST_HEAD(struct list_head *list)
  39 {
  40         list->next = list;
  41         list->prev = list;
  42 }
  43
  44 /*
  45  * Insert a new entry between two known consecutive entries.
  46  *
  47  * This is only for internal list manipulation where we know
  48  * the prev/next entries already!
  49  */
  50 static inline void __list_add(struct list_head *new,
  51                               struct list_head *prev,
  52                               struct list_head *next)
  53 {
  54         next->prev = new;
  55         new->next = next;
  56         new->prev = prev;
  57         prev->next = new;
  58 }
  59
  60 /**
  61  * list_add - add a new entry
  62  * @new: new entry to be added
  63  * @head: list head to add it after
  64  *
  65  * Insert a new entry after the specified head.
  66  * This is good for implementing stacks.
  67  */
  68 static inline void list_add(struct list_head *new, struct list_head *head)
  69 {
  70         __list_add(new, head, head->next);
  71 }
  72
  73 /**
  74  * list_add_tail - add a new entry
  75  * @new: new entry to be added
  76  * @head: list head to add it before
  77  *
  78  * Insert a new entry before the specified head.
  79  * This is useful for implementing queues.
  80  */
  81 static inline void list_add_tail(struct list_head *new, struct list_head *head)
  82 {
  83         __list_add(new, head->prev, head);
  84 }
  85
  86
  87 /*
  88  * Delete a list entry by making the prev/next entries
  89  * point to each other.
  90  *
  91  * This is only for internal list manipulation where we know
  92  * the prev/next entries already!
  93  */
  94 static inline void __list_del(struct list_head * prev, struct list_head * next)
  95 {
  96         next->prev = prev;
  97         prev->next = next;
  98 }
  99
 100 /**
 101  * list_del - deletes entry from list.
 102  * @entry: the element to delete from the list.
 103  * Note: list_empty on entry does not return true after this, the entry is
 104  * in an undefined state.
 105  */
 106 static inline void list_del(struct list_head *entry)
 107 {
 108         __list_del(entry->prev, entry->next);
 109 #ifndef NDEBUG
 110         entry->next = entry->prev = NULL;
 111 #endif
 112 }
 113
 114 /**
 115  * list_del_init - deletes entry from list and reinitialize it.
 116  * @entry: the element to delete from the list.
 117  */
 118 static inline void list_del_init(struct list_head *entry)
 119 {
 120         __list_del(entry->prev, entry->next);
 121         INIT_LIST_HEAD(entry);
 122 }
 123
 124 /**
 125  * list_move - delete from one list and add as another's head
 126  * @list: the entry to move
 127  * @head: the head that will precede our entry
 128  */
 129 static inline void list_move(struct list_head *list, struct list_head *head)
 130 {
 131         __list_del(list->prev, list->next);
 132         list_add(list, head);
 133 }
 134
 135 /**
 136  * list_move_tail - delete from one list and add as another's tail
 137  * @list: the entry to move
 138  * @head: the head that will follow our entry
 139  */
 140 static inline void list_move_tail(struct list_head *list,
 141                                   struct list_head *head)
 142 {
 143         __list_del(list->prev, list->next);
 144         list_add_tail(list, head);
 145 }
 146
 147 /**
 148  * list_is_last - tests whether @list is the last entry in list @head
 149  * @list: the entry to test
 150  * @head: the head of the list
 151  */
 152 static inline int list_is_last(const struct list_head *list,
 153                                 const struct list_head *head)
 154 {
 155         return list->next == head;
 156 }
 157
 158 /**
 159  * list_empty - tests whether a list is empty
 160  * @head: the list to test.
 161  */
 162 static inline int list_empty(const struct list_head *head)
 163 {
 164         return head->next == head;
 165 }
 166
 167 static inline void __list_splice(const struct list_head *list,
 168                                  struct list_head *head)
 169 {
 170         struct list_head *first = list->next;
 171         struct list_head *last = list->prev;
 172         struct list_head *at = head->next;
 173
 174         first->prev = head;
 175         head->next = first;
 176
 177         last->next = at;
 178         at->prev = last;
 179 }
 180
 181 /**
 182  * list_splice - join two lists
 183  * @list: the new list to add.
 184  * @head: the place to add it in the first list.
 185  */
 186 static inline void list_splice(const struct list_head *list,
 187                                 struct list_head *head)
 188 {
 189         if (!list_empty(list))
 190                 __list_splice(list, head);
 191 }
 192
 193 /**
 194  * list_entry - get the struct for this entry
 195  * @ptr:        the &struct list_head pointer.
 196  * @type:       the type of the struct this is embedded in.
 197  * @member:     the name of the struct list_head within the struct.
 198  */
 199 #define list_entry(ptr, type, member) ({                        \
 200         const struct list_head *__mptr = (ptr); \
 201         (type *)( (char *)__mptr - offsetof(type,member) );})
 202
 203 /**
 204  * list_for_each        -       iterate over a list
 205  * @pos:        the &struct list_head to use as a loop cursor.
 206  * @head:       the head for your list.
 207  */
 208 #define list_for_each(pos, head) \
 209         for (pos = (head)->next; pos != (head); pos = pos->next)
 210
 211 /**
 212  * list_for_each_prev   -       iterate over a list backwards
 213  * @pos:        the &struct list_head to use as a loop cursor.
 214  * @head:       the head for your list.
 215  */
 216 #define list_for_each_prev(pos, head) \
 217         for (pos = (head)->prev; pos != (head); pos = pos->prev)
 218
 219 /**
 220  * list_for_each_safe - iterate over a list safe against removal of list entry
 221  * @pos:        the &struct list_head to use as a loop cursor.
 222  * @n:          another &struct list_head to use as temporary storage
 223  * @head:       the head for your list.
 224  */
 225 #define list_for_each_safe(pos, n, head) \
 226         for (pos = (head)->next, n = pos->next; pos != (head); \
 227                 pos = n, n = pos->next)
 228
 229 /**
 230  * list_for_each_entry  -       iterate over list of given type
 231  * @pos:        the type * to use as a loop cursor.
 232  * @head:       the head for your list.
 233  * @member:     the name of the list_struct within the struct.
 234  */
 235 #define list_for_each_entry(pos, head, member)                          \
 236         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 237              &pos->member != (head);                                    \
 238              pos = list_entry(pos->member.next, typeof(*pos), member))
 239
 240 /**
 241  * list_for_each_entry_reverse - iterate backwards over list of given type.
 242  * @pos:        the type * to use as a loop cursor.
 243  * @head:       the head for your list.
 244  * @member:     the name of the list_struct within the struct.
 245  */
 246 #define list_for_each_entry_reverse(pos, head, member)                  \
 247         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
 248              &pos->member != (head);                                    \
 249              pos = list_entry(pos->member.prev, typeof(*pos), member))
 250
 251 /**
 252  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 253  * @pos:        the type * to use as a loop cursor.
 254  * @n:          another type * to use as temporary storage
 255  * @head:       the head for your list.
 256  * @member:     the name of the list_struct within the struct.
 257  */
 258 #define list_for_each_entry_safe(pos, n, head, member)                  \
 259         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 260                 n = list_entry(pos->member.next, typeof(*pos), member); \
 261              &pos->member != (head);                                    \
 262              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 263
 264 /**
 265  * list_for_each_entry_safe_reverse
 266  * @pos:        the type * to use as a loop cursor.
 267  * @n:          another type * to use as temporary storage
 268  * @head:       the head for your list.
 269  * @member:     the name of the list_struct within the struct.
 270  *
 271  * Iterate backwards over list of given type, safe against removal
 272  * of list entry.
 273  */
 274 #define list_for_each_entry_safe_reverse(pos, n, head, member)          \
 275         for (pos = list_entry((head)->prev, typeof(*pos), member),      \
 276                 n = list_entry(pos->member.prev, typeof(*pos), member); \
 277              &pos->member != (head);                                    \
 278              pos = n, n = list_entry(n->member.prev, typeof(*n), member))
 279
 280
 281 #endif /* EL__UTIL_LISTS_H */