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  1. /*
  2.  * Copyright (c) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup libc
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #ifndef LIBC_LIST_H_
  36. #define LIBC_LIST_H_
  37.  
  38. #include <unistd.h>
  39.  
  40. /** Doubly linked list head and link type. */
  41. typedef struct link {
  42.     struct link *prev;  /**< Pointer to the previous item in the list. */
  43.     struct link *next;  /**< Pointer to the next item in the list. */
  44. } link_t;
  45.  
  46. /** Declare and initialize statically allocated list.
  47.  *
  48.  * @param name Name of the new statically allocated list.
  49.  */
  50. #define LIST_INITIALIZE(name)  link_t name = { \
  51.     .prev = &name, \
  52.     .next = &name \
  53. }
  54.  
  55. /** Initialize doubly-linked circular list link
  56.  *
  57.  * Initialize doubly-linked list link.
  58.  *
  59.  * @param link Pointer to link_t structure to be initialized.
  60.  */
  61. static inline void link_initialize(link_t *link)
  62. {
  63.     link->prev = NULL;
  64.     link->next = NULL;
  65. }
  66.  
  67. /** Initialize doubly-linked circular list
  68.  *
  69.  * Initialize doubly-linked circular list.
  70.  *
  71.  * @param head Pointer to link_t structure representing head of the list.
  72.  */
  73. static inline void list_initialize(link_t *head)
  74. {
  75.     head->prev = head;
  76.     head->next = head;
  77. }
  78.  
  79. /** Add item to the beginning of doubly-linked circular list
  80.  *
  81.  * Add item to the beginning of doubly-linked circular list.
  82.  *
  83.  * @param link Pointer to link_t structure to be added.
  84.  * @param head Pointer to link_t structure representing head of the list.
  85.  */
  86. static inline void list_prepend(link_t *link, link_t *head)
  87. {
  88.     link->next = head->next;
  89.     link->prev = head;
  90.     head->next->prev = link;
  91.     head->next = link;
  92. }
  93.  
  94. /** Add item to the end of doubly-linked circular list
  95.  *
  96.  * Add item to the end of doubly-linked circular list.
  97.  *
  98.  * @param link Pointer to link_t structure to be added.
  99.  * @param head Pointer to link_t structure representing head of the list.
  100.  */
  101. static inline void list_append(link_t *link, link_t *head)
  102. {
  103.     link->prev = head->prev;
  104.     link->next = head;
  105.     head->prev->next = link;
  106.     head->prev = link;
  107. }
  108.  
  109. /** Insert item before another item in doubly-linked circular list. */
  110. static inline void list_insert_before(link_t *l, link_t *r)
  111. {
  112.     list_append(l, r);
  113. }
  114.  
  115. /** Insert item after another item in doubly-linked circular list. */
  116. static inline void list_insert_after(link_t *r, link_t *l)
  117. {
  118.     list_prepend(l, r);
  119. }
  120.  
  121. /** Remove item from doubly-linked circular list
  122.  *
  123.  * Remove item from doubly-linked circular list.
  124.  *
  125.  * @param link Pointer to link_t structure to be removed from the list it is contained in.
  126.  */
  127. static inline void list_remove(link_t *link)
  128. {
  129.     link->next->prev = link->prev;
  130.     link->prev->next = link->next;
  131.     link_initialize(link);
  132. }
  133.  
  134. /** Query emptiness of doubly-linked circular list
  135.  *
  136.  * Query emptiness of doubly-linked circular list.
  137.  *
  138.  * @param head Pointer to link_t structure representing head of the list.
  139.  */
  140. static inline int list_empty(link_t *head)
  141. {
  142.     return ((head->next == head) ? 1 : 0);
  143. }
  144.  
  145.  
  146. /** Split or concatenate headless doubly-linked circular list
  147.  *
  148.  * Split or concatenate headless doubly-linked circular list.
  149.  *
  150.  * Note that the algorithm works both directions:
  151.  * concatenates splitted lists and splits concatenated lists.
  152.  *
  153.  * @param part1 Pointer to link_t structure leading the first (half of the headless) list.
  154.  * @param part2 Pointer to link_t structure leading the second (half of the headless) list.
  155.  */
  156. static inline void headless_list_split_or_concat(link_t *part1, link_t *part2)
  157. {
  158.     part1->prev->next = part2;
  159.     part2->prev->next = part1;
  160.    
  161.     link_t *hlp = part1->prev;
  162.    
  163.     part1->prev = part2->prev;
  164.     part2->prev = hlp;
  165. }
  166.  
  167.  
  168. /** Split headless doubly-linked circular list
  169.  *
  170.  * Split headless doubly-linked circular list.
  171.  *
  172.  * @param part1 Pointer to link_t structure leading the first half of the headless list.
  173.  * @param part2 Pointer to link_t structure leading the second half of the headless list.
  174.  */
  175. static inline void headless_list_split(link_t *part1, link_t *part2)
  176. {
  177.     headless_list_split_or_concat(part1, part2);
  178. }
  179.  
  180. /** Concatenate two headless doubly-linked circular lists
  181.  *
  182.  * Concatenate two headless doubly-linked circular lists.
  183.  *
  184.  * @param part1 Pointer to link_t structure leading the first headless list.
  185.  * @param part2 Pointer to link_t structure leading the second headless list.
  186.  */
  187. static inline void headless_list_concat(link_t *part1, link_t *part2)
  188. {
  189.     headless_list_split_or_concat(part1, part2);
  190. }
  191.  
  192. #define list_get_instance(link, type, member)  ((type *) (((void *)(link)) - ((void *) &(((type *) NULL)->member))))
  193.  
  194. extern int list_member(const link_t *link, const link_t *head);
  195. extern void list_concat(link_t *head1, link_t *head2);
  196. extern unsigned int list_count(const link_t *link);
  197.  
  198. #endif
  199.  
  200. /** @}
  201.  */
  202.