/* * Copyright © 2010 Intel Corporation * Copyright © 2010 Francisco Jerez <currojerez@riseup.net> * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. * */ #ifndef _LIST_H_ #define _LIST_H_ /** * @file Classic doubly-link circular list implementation. * * Example: * We need to keep a list of struct foo in the parent struct bar, i.e. what * we want is something like this. * * struct bar { * ... * struct foo *foos; -----> struct foo {}, struct foo {}, struct foo{} * ... * } * * We need one list head in bar and a list element in all foos (both are of * data type 'struct list'). * * struct bar { * ... * struct list foos; * ... * } * * struct foo { * ... * struct list entry; * ... * } * * Now we initialize the list head: * * struct bar bar; * ... * list_init(&bar.foos); * * Then we create the first element and add it to this list: * * struct foo *foo = malloc(...); * .... * list_add(&foo->entry, &bar.foos); * * Repeat the above for each element you want to add to the list. Deleting * works with the element itself. * list_del(&foo->entry); * free(foo); * * Note: calling list_del(&bar.foos) will set bar.foos to an empty * list again. * * Looping through the list requires a 'struct foo' as iterator and the * name of the field the subnodes use. * * struct foo *iterator; * list_for_each_entry(iterator, &bar.foos, entry) { * if (iterator->something == ...) * ... * } * * Note: You must not call list_del() on the iterator if you continue the * loop. You need to run the safe for-each loop instead: * * struct foo *iterator, *next; * list_for_each_entry_safe(iterator, next, &bar.foos, entry) { * if (...) * list_del(&iterator->entry); * } * */ /** * The linkage struct for list nodes. This struct must be part of your * to-be-linked struct. * * Example: * struct foo { * int a; * void *b; * struct list *mylist; * } * * Position and name of the struct list field is irrelevant. * There are no requirements that elements of a list are of the same type. * There are no requirements for a list head, any struct list can be a list * head. */ struct list { struct list *next, *prev; }; /** * Initialize the list as an empty list. * * Example: * list_init(&foo->mylist); * * @param The list to initialized. */ static void list_init(struct list *list) { list->next = list->prev = list; } static inline void __list_add(struct list *entry, struct list *prev, struct list *next) { next->prev = entry; entry->next = next; entry->prev = prev; prev->next = entry; } /** * Insert a new element after the given list head. * The list changes from: * head → some element → ... * to * head → new element → older element → ... * * Example: * struct foo *newfoo = malloc(...); * list_add(&newfoo->mylist, &foo->mylist); * * @param entry The new element to prepend to the list. * @param head The existing list. */ static inline void list_add(struct list *entry, struct list *head) { __list_add(entry, head, head->next); } static inline void __list_del(struct list *prev, struct list *next) { next->prev = prev; prev->next = next; } /** * Remove the element from the list it is in. Using this function will reset * the pointers to/from this element so it is removed from the list. It does * NOT free the element itself or manipulate it otherwise. * * Using list_del on a pure list head (like in the example at the top of * this file) will NOT remove the first element from * the list but rather reset the list as empty list. * * Example: * list_del(&newfoo->mylist); * * @param entry The element to remove. */ static inline void list_del(struct list *entry) { __list_del(entry->prev, entry->next); list_init(entry); } /** * Check if the list is empty. * * Example: * list_is_empty(&foo->mylist); * * @return True if the list contains one or more elements or False otherwise. */ static inline Bool list_is_empty(struct list *head) { return head->next == head; } /** * Returns a pointer to the container of this list element. * * Example: * struct foo* f; * f = container_of(&foo->mylist, struct foo, mylist); * assert(f == foo); * * @param ptr Pointer to the struct list. * @param type Data type of the list element. * @param member Member name of the struct list field in the list element. * @return A pointer to the data struct containing the list head. */ #ifndef container_of #define container_of(ptr, type, member) \ (type *)((char *)(ptr) - (char *) &((type *)0)->member) #endif /** * Alias of container_of */ #define list_entry(ptr, type, member) \ container_of(ptr, type, member) /** * Retrieve the first list entry for the given list pointer. * * Example: * struct foo *first; * first = list_first_entry(&foo->mylist, struct foo, mylist); * * @param ptr The list head * @param type Data type of the list element to retrieve * @param member Member name of the struct list field in the list element. * @return A pointer to the first list element. */ #define list_first_entry(ptr, type, member) \ list_entry((ptr)->next, type, member) #define __container_of(ptr, sample, member) \ (void *)((char *)(ptr) \ - ((char *)&(sample)->member - (char *)(sample))) /** * Loop through the list given by head and set pos to struct in the list. * * Example: * struct foo *iterator; * list_for_each_entry(iterator, &foo->mylist, mylist) { * [modify iterator] * } * * This macro is not safe for node deletion. Use list_for_each_entry_safe * instead. * * @param pos Iterator variable of the type of the list elements. * @param head List head * @param member Member name of the struct list in the list elements. * */ #define list_for_each_entry(pos, head, member) \ for (pos = __container_of((head)->next, pos, member); \ &pos->member != (head); \ pos = __container_of(pos->member.next, pos, member)) /** * Loop through the list, keeping a backup pointer to the element. This * macro allows for the deletion of a list element while looping through the * list. * * See list_for_each_entry for more details. */ #define list_for_each_entry_safe(pos, tmp, head, member) \ for (pos = __container_of((head)->next, pos, member), \ tmp = __container_of(pos->member.next, pos, member); \ &pos->member != (head); \ pos = tmp, tmp = __container_of(pos->member.next, tmp, member)) #endif