1 /** @file
2 Linked List Library Functions.
3
4 Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
5 This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php.
9
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13 **/
14
15 #include "BaseLibInternals.h"
16
17 /**
18 Worker function that locates the Node in the List.
19
20 By searching the List, finds the location of the Node in List. At the same time,
21 verifies the validity of this list.
22
23 If List is NULL, then ASSERT().
24 If List->ForwardLink is NULL, then ASSERT().
25 If List->backLink is NULL, then ASSERT().
26 If Node is NULL, then ASSERT().
27 If PcdVerifyNodeInList is TRUE and DoMembershipCheck is TRUE and Node
28 is in not a member of List, then return FALSE
29 If PcdMaximumLinkedListLength is not zero, and List contains more than
30 PcdMaximumLinkedListLength nodes, then ASSERT().
31
32 @param List A pointer to a node in a linked list.
33 @param Node A pointer to a node in a linked list.
34 @param VerifyNodeInList TRUE if a check should be made to see if Node is a
35 member of List. FALSE if no membership test should
36 be performed.
37
38 @retval TRUE if PcdVerifyNodeInList is FALSE
39 @retval TRUE if DoMembershipCheck is FALSE
40 @retval TRUE if PcdVerifyNodeInList is TRUE and DoMembershipCheck is TRUE
41 and Node is a member of List.
42 @retval FALSE if PcdVerifyNodeInList is TRUE and DoMembershipCheck is TRUE
43 and Node is in not a member of List.
44
45 **/
46 BOOLEAN
47 EFIAPI
InternalBaseLibIsNodeInList(IN CONST LIST_ENTRY * List,IN CONST LIST_ENTRY * Node,IN BOOLEAN VerifyNodeInList)48 InternalBaseLibIsNodeInList (
49 IN CONST LIST_ENTRY *List,
50 IN CONST LIST_ENTRY *Node,
51 IN BOOLEAN VerifyNodeInList
52 )
53 {
54 UINTN Count;
55 CONST LIST_ENTRY *Ptr;
56
57 //
58 // Test the validity of List and Node
59 //
60 ASSERT (List != NULL);
61 ASSERT (List->ForwardLink != NULL);
62 ASSERT (List->BackLink != NULL);
63 ASSERT (Node != NULL);
64
65 Count = 0;
66 Ptr = List;
67
68 if (FeaturePcdGet (PcdVerifyNodeInList) && VerifyNodeInList) {
69 //
70 // Check to see if Node is a member of List.
71 // Exit early if the number of nodes in List >= PcdMaximumLinkedListLength
72 //
73 do {
74 Ptr = Ptr->ForwardLink;
75 if (PcdGet32 (PcdMaximumLinkedListLength) > 0) {
76 Count++;
77 //
78 // ASSERT() if the linked list is too long
79 //
80 ASSERT (Count < PcdGet32 (PcdMaximumLinkedListLength));
81
82 //
83 // Return if the linked list is too long
84 //
85 if (Count >= PcdGet32 (PcdMaximumLinkedListLength)) {
86 return (BOOLEAN)(Ptr == Node);
87 }
88 }
89 } while ((Ptr != List) && (Ptr != Node));
90
91 if (Ptr != Node) {
92 return FALSE;
93 }
94 }
95
96 if (PcdGet32 (PcdMaximumLinkedListLength) > 0) {
97 //
98 // Count the total number of nodes in List.
99 // Exit early if the number of nodes in List >= PcdMaximumLinkedListLength
100 //
101 do {
102 Ptr = Ptr->ForwardLink;
103 Count++;
104 } while ((Ptr != List) && (Count < PcdGet32 (PcdMaximumLinkedListLength)));
105
106 //
107 // ASSERT() if the linked list is too long
108 //
109 ASSERT (Count < PcdGet32 (PcdMaximumLinkedListLength));
110 }
111
112 return TRUE;
113 }
114
115 /**
116 Initializes the head node of a doubly-linked list, and returns the pointer to
117 the head node of the doubly-linked list.
118
119 Initializes the forward and backward links of a new linked list. After
120 initializing a linked list with this function, the other linked list
121 functions may be used to add and remove nodes from the linked list. It is up
122 to the caller of this function to allocate the memory for ListHead.
123
124 If ListHead is NULL, then ASSERT().
125
126 @param ListHead A pointer to the head node of a new doubly-linked list.
127
128 @return ListHead
129
130 **/
131 LIST_ENTRY *
132 EFIAPI
InitializeListHead(IN OUT LIST_ENTRY * ListHead)133 InitializeListHead (
134 IN OUT LIST_ENTRY *ListHead
135 )
136
137 {
138 ASSERT (ListHead != NULL);
139
140 ListHead->ForwardLink = ListHead;
141 ListHead->BackLink = ListHead;
142 return ListHead;
143 }
144
145 /**
146 Adds a node to the beginning of a doubly-linked list, and returns the pointer
147 to the head node of the doubly-linked list.
148
149 Adds the node Entry at the beginning of the doubly-linked list denoted by
150 ListHead, and returns ListHead.
151
152 If ListHead is NULL, then ASSERT().
153 If Entry is NULL, then ASSERT().
154 If ListHead was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
155 InitializeListHead(), then ASSERT().
156 If PcdMaximumLinkedListLength is not zero, and prior to insertion the number
157 of nodes in ListHead, including the ListHead node, is greater than or
158 equal to PcdMaximumLinkedListLength, then ASSERT().
159
160 @param ListHead A pointer to the head node of a doubly-linked list.
161 @param Entry A pointer to a node that is to be inserted at the beginning
162 of a doubly-linked list.
163
164 @return ListHead
165
166 **/
167 LIST_ENTRY *
168 EFIAPI
InsertHeadList(IN OUT LIST_ENTRY * ListHead,IN OUT LIST_ENTRY * Entry)169 InsertHeadList (
170 IN OUT LIST_ENTRY *ListHead,
171 IN OUT LIST_ENTRY *Entry
172 )
173 {
174 //
175 // ASSERT List not too long and Entry is not one of the nodes of List
176 //
177 ASSERT (InternalBaseLibIsNodeInList (ListHead, Entry, FALSE));
178
179 Entry->ForwardLink = ListHead->ForwardLink;
180 Entry->BackLink = ListHead;
181 Entry->ForwardLink->BackLink = Entry;
182 ListHead->ForwardLink = Entry;
183 return ListHead;
184 }
185
186 /**
187 Adds a node to the end of a doubly-linked list, and returns the pointer to
188 the head node of the doubly-linked list.
189
190 Adds the node Entry to the end of the doubly-linked list denoted by ListHead,
191 and returns ListHead.
192
193 If ListHead is NULL, then ASSERT().
194 If Entry is NULL, then ASSERT().
195 If ListHead was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
196 InitializeListHead(), then ASSERT().
197 If PcdMaximumLinkedListLength is not zero, and prior to insertion the number
198 of nodes in ListHead, including the ListHead node, is greater than or
199 equal to PcdMaximumLinkedListLength, then ASSERT().
200
201 @param ListHead A pointer to the head node of a doubly-linked list.
202 @param Entry A pointer to a node that is to be added at the end of the
203 doubly-linked list.
204
205 @return ListHead
206
207 **/
208 LIST_ENTRY *
209 EFIAPI
InsertTailList(IN OUT LIST_ENTRY * ListHead,IN OUT LIST_ENTRY * Entry)210 InsertTailList (
211 IN OUT LIST_ENTRY *ListHead,
212 IN OUT LIST_ENTRY *Entry
213 )
214 {
215 //
216 // ASSERT List not too long and Entry is not one of the nodes of List
217 //
218 ASSERT (InternalBaseLibIsNodeInList (ListHead, Entry, FALSE));
219
220 Entry->ForwardLink = ListHead;
221 Entry->BackLink = ListHead->BackLink;
222 Entry->BackLink->ForwardLink = Entry;
223 ListHead->BackLink = Entry;
224 return ListHead;
225 }
226
227 /**
228 Retrieves the first node of a doubly-linked list.
229
230 Returns the first node of a doubly-linked list. List must have been
231 initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead().
232 If List is empty, then List is returned.
233
234 If List is NULL, then ASSERT().
235 If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
236 InitializeListHead(), then ASSERT().
237 If PcdMaximumLinkedListLength is not zero, and the number of nodes
238 in List, including the List node, is greater than or equal to
239 PcdMaximumLinkedListLength, then ASSERT().
240
241 @param List A pointer to the head node of a doubly-linked list.
242
243 @return The first node of a doubly-linked list.
244 @retval List The list is empty.
245
246 **/
247 LIST_ENTRY *
248 EFIAPI
GetFirstNode(IN CONST LIST_ENTRY * List)249 GetFirstNode (
250 IN CONST LIST_ENTRY *List
251 )
252 {
253 //
254 // ASSERT List not too long
255 //
256 ASSERT (InternalBaseLibIsNodeInList (List, List, FALSE));
257
258 return List->ForwardLink;
259 }
260
261 /**
262 Retrieves the next node of a doubly-linked list.
263
264 Returns the node of a doubly-linked list that follows Node.
265 List must have been initialized with INTIALIZE_LIST_HEAD_VARIABLE()
266 or InitializeListHead(). If List is empty, then List is returned.
267
268 If List is NULL, then ASSERT().
269 If Node is NULL, then ASSERT().
270 If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
271 InitializeListHead(), then ASSERT().
272 If PcdMaximumLinkedListLength is not zero, and List contains more than
273 PcdMaximumLinkedListLength nodes, then ASSERT().
274 If PcdVerifyNodeInList is TRUE and Node is not a node in List, then ASSERT().
275
276 @param List A pointer to the head node of a doubly-linked list.
277 @param Node A pointer to a node in the doubly-linked list.
278
279 @return A pointer to the next node if one exists. Otherwise List is returned.
280
281 **/
282 LIST_ENTRY *
283 EFIAPI
GetNextNode(IN CONST LIST_ENTRY * List,IN CONST LIST_ENTRY * Node)284 GetNextNode (
285 IN CONST LIST_ENTRY *List,
286 IN CONST LIST_ENTRY *Node
287 )
288 {
289 //
290 // ASSERT List not too long and Node is one of the nodes of List
291 //
292 ASSERT (InternalBaseLibIsNodeInList (List, Node, TRUE));
293
294 return Node->ForwardLink;
295 }
296
297 /**
298 Retrieves the previous node of a doubly-linked list.
299
300 Returns the node of a doubly-linked list that precedes Node.
301 List must have been initialized with INTIALIZE_LIST_HEAD_VARIABLE()
302 or InitializeListHead(). If List is empty, then List is returned.
303
304 If List is NULL, then ASSERT().
305 If Node is NULL, then ASSERT().
306 If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
307 InitializeListHead(), then ASSERT().
308 If PcdMaximumLinkedListLength is not zero, and List contains more than
309 PcdMaximumLinkedListLength nodes, then ASSERT().
310 If PcdVerifyNodeInList is TRUE and Node is not a node in List, then ASSERT().
311
312 @param List A pointer to the head node of a doubly-linked list.
313 @param Node A pointer to a node in the doubly-linked list.
314
315 @return A pointer to the previous node if one exists. Otherwise List is returned.
316
317 **/
318 LIST_ENTRY *
319 EFIAPI
GetPreviousNode(IN CONST LIST_ENTRY * List,IN CONST LIST_ENTRY * Node)320 GetPreviousNode (
321 IN CONST LIST_ENTRY *List,
322 IN CONST LIST_ENTRY *Node
323 )
324 {
325 //
326 // ASSERT List not too long and Node is one of the nodes of List
327 //
328 ASSERT (InternalBaseLibIsNodeInList (List, Node, TRUE));
329
330 return Node->BackLink;
331 }
332
333 /**
334 Checks to see if a doubly-linked list is empty or not.
335
336 Checks to see if the doubly-linked list is empty. If the linked list contains
337 zero nodes, this function returns TRUE. Otherwise, it returns FALSE.
338
339 If ListHead is NULL, then ASSERT().
340 If ListHead was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
341 InitializeListHead(), then ASSERT().
342 If PcdMaximumLinkedListLength is not zero, and the number of nodes
343 in List, including the List node, is greater than or equal to
344 PcdMaximumLinkedListLength, then ASSERT().
345
346 @param ListHead A pointer to the head node of a doubly-linked list.
347
348 @retval TRUE The linked list is empty.
349 @retval FALSE The linked list is not empty.
350
351 **/
352 BOOLEAN
353 EFIAPI
IsListEmpty(IN CONST LIST_ENTRY * ListHead)354 IsListEmpty (
355 IN CONST LIST_ENTRY *ListHead
356 )
357 {
358 //
359 // ASSERT List not too long
360 //
361 ASSERT (InternalBaseLibIsNodeInList (ListHead, ListHead, FALSE));
362
363 return (BOOLEAN)(ListHead->ForwardLink == ListHead);
364 }
365
366 /**
367 Determines if a node in a doubly-linked list is the head node of a the same
368 doubly-linked list. This function is typically used to terminate a loop that
369 traverses all the nodes in a doubly-linked list starting with the head node.
370
371 Returns TRUE if Node is equal to List. Returns FALSE if Node is one of the
372 nodes in the doubly-linked list specified by List. List must have been
373 initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead().
374
375 If List is NULL, then ASSERT().
376 If Node is NULL, then ASSERT().
377 If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead(),
378 then ASSERT().
379 If PcdMaximumLinkedListLength is not zero, and the number of nodes
380 in List, including the List node, is greater than or equal to
381 PcdMaximumLinkedListLength, then ASSERT().
382 If PcdVerifyNodeInList is TRUE and Node is not a node in List and Node is not
383 equal to List, then ASSERT().
384
385 @param List A pointer to the head node of a doubly-linked list.
386 @param Node A pointer to a node in the doubly-linked list.
387
388 @retval TRUE Node is the head of the doubly-linked list pointed by List.
389 @retval FALSE Node is not the head of the doubly-linked list pointed by List.
390
391 **/
392 BOOLEAN
393 EFIAPI
IsNull(IN CONST LIST_ENTRY * List,IN CONST LIST_ENTRY * Node)394 IsNull (
395 IN CONST LIST_ENTRY *List,
396 IN CONST LIST_ENTRY *Node
397 )
398 {
399 //
400 // ASSERT List not too long and Node is one of the nodes of List
401 //
402 ASSERT (InternalBaseLibIsNodeInList (List, Node, TRUE));
403
404 return (BOOLEAN)(Node == List);
405 }
406
407 /**
408 Determines if a node the last node in a doubly-linked list.
409
410 Returns TRUE if Node is the last node in the doubly-linked list specified by
411 List. Otherwise, FALSE is returned. List must have been initialized with
412 INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead().
413
414 If List is NULL, then ASSERT().
415 If Node is NULL, then ASSERT().
416 If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
417 InitializeListHead(), then ASSERT().
418 If PcdMaximumLinkedListLength is not zero, and the number of nodes
419 in List, including the List node, is greater than or equal to
420 PcdMaximumLinkedListLength, then ASSERT().
421 If PcdVerifyNodeInList is TRUE and Node is not a node in List, then ASSERT().
422
423 @param List A pointer to the head node of a doubly-linked list.
424 @param Node A pointer to a node in the doubly-linked list.
425
426 @retval TRUE Node is the last node in the linked list.
427 @retval FALSE Node is not the last node in the linked list.
428
429 **/
430 BOOLEAN
431 EFIAPI
IsNodeAtEnd(IN CONST LIST_ENTRY * List,IN CONST LIST_ENTRY * Node)432 IsNodeAtEnd (
433 IN CONST LIST_ENTRY *List,
434 IN CONST LIST_ENTRY *Node
435 )
436 {
437 //
438 // ASSERT List not too long and Node is one of the nodes of List
439 //
440 ASSERT (InternalBaseLibIsNodeInList (List, Node, TRUE));
441
442 return (BOOLEAN)(!IsNull (List, Node) && List->BackLink == Node);
443 }
444
445 /**
446 Swaps the location of two nodes in a doubly-linked list, and returns the
447 first node after the swap.
448
449 If FirstEntry is identical to SecondEntry, then SecondEntry is returned.
450 Otherwise, the location of the FirstEntry node is swapped with the location
451 of the SecondEntry node in a doubly-linked list. SecondEntry must be in the
452 same double linked list as FirstEntry and that double linked list must have
453 been initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead().
454 SecondEntry is returned after the nodes are swapped.
455
456 If FirstEntry is NULL, then ASSERT().
457 If SecondEntry is NULL, then ASSERT().
458 If PcdVerifyNodeInList is TRUE and SecondEntry and FirstEntry are not in the
459 same linked list, then ASSERT().
460 If PcdMaximumLinkedListLength is not zero, and the number of nodes in the
461 linked list containing the FirstEntry and SecondEntry nodes, including
462 the FirstEntry and SecondEntry nodes, is greater than or equal to
463 PcdMaximumLinkedListLength, then ASSERT().
464
465 @param FirstEntry A pointer to a node in a linked list.
466 @param SecondEntry A pointer to another node in the same linked list.
467
468 @return SecondEntry.
469
470 **/
471 LIST_ENTRY *
472 EFIAPI
SwapListEntries(IN OUT LIST_ENTRY * FirstEntry,IN OUT LIST_ENTRY * SecondEntry)473 SwapListEntries (
474 IN OUT LIST_ENTRY *FirstEntry,
475 IN OUT LIST_ENTRY *SecondEntry
476 )
477 {
478 LIST_ENTRY *Ptr;
479
480 if (FirstEntry == SecondEntry) {
481 return SecondEntry;
482 }
483
484 //
485 // ASSERT Entry1 and Entry2 are in the same linked list
486 //
487 ASSERT (InternalBaseLibIsNodeInList (FirstEntry, SecondEntry, TRUE));
488
489 //
490 // Ptr is the node pointed to by FirstEntry->ForwardLink
491 //
492 Ptr = RemoveEntryList (FirstEntry);
493
494 //
495 // If FirstEntry immediately follows SecondEntry, FirstEntry will be placed
496 // immediately in front of SecondEntry
497 //
498 if (Ptr->BackLink == SecondEntry) {
499 return InsertTailList (SecondEntry, FirstEntry);
500 }
501
502 //
503 // Ptr == SecondEntry means SecondEntry immediately follows FirstEntry,
504 // then there are no further steps necessary
505 //
506 if (Ptr == InsertHeadList (SecondEntry, FirstEntry)) {
507 return Ptr;
508 }
509
510 //
511 // Move SecondEntry to the front of Ptr
512 //
513 RemoveEntryList (SecondEntry);
514 InsertTailList (Ptr, SecondEntry);
515 return SecondEntry;
516 }
517
518 /**
519 Removes a node from a doubly-linked list, and returns the node that follows
520 the removed node.
521
522 Removes the node Entry from a doubly-linked list. It is up to the caller of
523 this function to release the memory used by this node if that is required. On
524 exit, the node following Entry in the doubly-linked list is returned. If
525 Entry is the only node in the linked list, then the head node of the linked
526 list is returned.
527
528 If Entry is NULL, then ASSERT().
529 If Entry is the head node of an empty list, then ASSERT().
530 If PcdMaximumLinkedListLength is not zero, and the number of nodes in the
531 linked list containing Entry, including the Entry node, is greater than
532 or equal to PcdMaximumLinkedListLength, then ASSERT().
533
534 @param Entry A pointer to a node in a linked list.
535
536 @return Entry.
537
538 **/
539 LIST_ENTRY *
540 EFIAPI
RemoveEntryList(IN CONST LIST_ENTRY * Entry)541 RemoveEntryList (
542 IN CONST LIST_ENTRY *Entry
543 )
544 {
545 ASSERT (!IsListEmpty (Entry));
546
547 Entry->ForwardLink->BackLink = Entry->BackLink;
548 Entry->BackLink->ForwardLink = Entry->ForwardLink;
549 return Entry->ForwardLink;
550 }
551