summaryrefslogtreecommitdiff
path: root/MdePkg/Library/BaseLib/LinkedList.c
blob: 8069bd3550fc753a812bc6f11f2adc3049225a3a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
/** @file
  Linked List Library Functions.

  Copyright (c) 2006 - 2008, Intel Corporation<BR>
  All rights reserved. This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "BaseLibInternals.h"

/**
  Worker function that locates the Node in the List.

  By searching the List, finds the location of the Node in List. At the same time,
  verifies the validity of this list.

  If List is NULL, then ASSERT().
  If List->ForwardLink is NULL, then ASSERT().
  If List->backLink is NULL, then ASSERT().
  If Node is NULL, then ASSERT();
  If PcdMaximumLinkedListLenth is not zero, and prior to insertion the number
  of nodes in ListHead, including the ListHead node, is greater than or
  equal to PcdMaximumLinkedListLength, then ASSERT().

  @param  List  A pointer to a node in a linked list.
  @param  Node  A pointer to one nod.

  @retval TRUE   Node is in List
  @retval FALSE  Node isn't in List, or List is invalid

**/
BOOLEAN
EFIAPI
IsNodeInList (
  IN      CONST LIST_ENTRY      *List,
  IN      CONST LIST_ENTRY      *Node
  )
{
  UINTN                         Count;
  CONST LIST_ENTRY              *Ptr;
  BOOLEAN                       Found;

  //
  // Test the validity of List and Node
  //
  ASSERT (List != NULL);
  ASSERT (List->ForwardLink != NULL);
  ASSERT (List->BackLink != NULL);
  ASSERT (Node != NULL);

  Count = PcdGet32 (PcdMaximumLinkedListLength);

  Ptr = List;
  do {
    Ptr = Ptr->ForwardLink;
    Count--;
  } while ((Ptr != List) && (Ptr != Node) && (Count > 0));
  Found = (BOOLEAN)(Ptr == Node);

  if (PcdGet32 (PcdMaximumLinkedListLength) > 0) {
    while ((Count > 0) && (Ptr != List)) {
      Ptr = Ptr->ForwardLink;
      Count--;
    }
    ASSERT (Count > 0);
  }

  return Found;
}

/**
  Initializes the head node of a doubly linked list, and returns the pointer to
  the head node of the doubly linked list.

  Initializes the forward and backward links of a new linked list. After
  initializing a linked list with this function, the other linked list
  functions may be used to add and remove nodes from the linked list. It is up
  to the caller of this function to allocate the memory for ListHead.

  If ListHead is NULL, then ASSERT().

  @param  ListHead  A pointer to the head node of a new doubly linked list.

  @return ListHead

**/
LIST_ENTRY *
EFIAPI
InitializeListHead (
  IN OUT  LIST_ENTRY                *ListHead
  )

{
  ASSERT (ListHead != NULL);

  ListHead->ForwardLink = ListHead;
  ListHead->BackLink = ListHead;
  return ListHead;
}

/**
  Adds a node to the beginning of a doubly linked list, and returns the pointer
  to the head node of the doubly linked list.

  Adds the node Entry at the beginning of the doubly linked list denoted by
  ListHead, and returns ListHead.

  If ListHead is NULL, then ASSERT().
  If Entry is NULL, then ASSERT().
  If ListHead was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
  InitializeListHead(), then ASSERT().
  If PcdMaximumLinkedListLenth is not zero, and prior to insertion the number
  of nodes in ListHead, including the ListHead node, is greater than or
  equal to PcdMaximumLinkedListLength, then ASSERT().

  @param  ListHead  A pointer to the head node of a doubly linked list.
  @param  Entry     A pointer to a node that is to be inserted at the beginning
                    of a doubly linked list.

  @return ListHead

**/
LIST_ENTRY *
EFIAPI
InsertHeadList (
  IN OUT  LIST_ENTRY                *ListHead,
  IN OUT  LIST_ENTRY                *Entry
  )
{
  //
  // ASSERT List not too long and Entry is not one of the nodes of List
  //
  ASSERT (!IsNodeInList (ListHead, Entry));

  Entry->ForwardLink = ListHead->ForwardLink;
  Entry->BackLink = ListHead;
  Entry->ForwardLink->BackLink = Entry;
  ListHead->ForwardLink = Entry;
  return ListHead;
}

/**
  Adds a node to the end of a doubly linked list, and returns the pointer to
  the head node of the doubly linked list.

  Adds the node Entry to the end of the doubly linked list denoted by ListHead,
  and returns ListHead.

  If ListHead is NULL, then ASSERT().
  If Entry is NULL, then ASSERT().
  If ListHead was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or 
  InitializeListHead(), then ASSERT().
  If PcdMaximumLinkedListLenth is not zero, and prior to insertion the number
  of nodes in ListHead, including the ListHead node, is greater than or
  equal to PcdMaximumLinkedListLength, then ASSERT().

  @param  ListHead  A pointer to the head node of a doubly linked list.
  @param  Entry     A pointer to a node that is to be added at the end of the
                    doubly linked list.

  @return ListHead

**/
LIST_ENTRY *
EFIAPI
InsertTailList (
  IN OUT  LIST_ENTRY                *ListHead,
  IN OUT  LIST_ENTRY                *Entry
  )
{
  //
  // ASSERT List not too long and Entry is not one of the nodes of List
  //
  ASSERT (!IsNodeInList (ListHead, Entry));

  Entry->ForwardLink = ListHead;
  Entry->BackLink = ListHead->BackLink;
  Entry->BackLink->ForwardLink = Entry;
  ListHead->BackLink = Entry;
  return ListHead;
}

/**
  Retrieves the first node of a doubly linked list.

  Returns the first node of a doubly linked list.  List must have been 
  initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead().
  If List is empty, then List is returned.

  If List is NULL, then ASSERT().
  If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or 
  InitializeListHead(), then ASSERT().
  If PcdMaximumLinkedListLenth is not zero, and the number of nodes
  in List, including the List node, is greater than or equal to
  PcdMaximumLinkedListLength, then ASSERT().

  @param  List  A pointer to the head node of a doubly linked list.

  @return The first node of a doubly linked list.
  @retval NULL  The list is empty.

**/
LIST_ENTRY *
EFIAPI
GetFirstNode (
  IN      CONST LIST_ENTRY          *List
  )
{
  //
  // ASSERT List not too long
  //
  ASSERT (IsNodeInList (List, List));

  return List->ForwardLink;
}

/**
  Retrieves the next node of a doubly linked list.

  Returns the node of a doubly linked list that follows Node.  
  List must have been initialized with INTIALIZE_LIST_HEAD_VARIABLE()
  or InitializeListHead().  If List is empty, then List is returned.

  If List is NULL, then ASSERT().
  If Node is NULL, then ASSERT().
  If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or 
  InitializeListHead(), then ASSERT().
  If PcdMaximumLinkedListLenth is not zero, and List contains more than
  PcdMaximumLinkedListLenth nodes, then ASSERT().
  If Node is not a node in List, then ASSERT().

  @param  List  A pointer to the head node of a doubly linked list.
  @param  Node  A pointer to a node in the doubly linked list.

  @return Pointer to the next node if one exists. Otherwise a null value which
          is actually List is returned.

**/
LIST_ENTRY *
EFIAPI
GetNextNode (
  IN      CONST LIST_ENTRY          *List,
  IN      CONST LIST_ENTRY          *Node
  )
{
  //
  // ASSERT List not too long and Node is one of the nodes of List
  //
  ASSERT (IsNodeInList (List, Node));

  return Node->ForwardLink;
}

/**
  Checks to see if a doubly linked list is empty or not.

  Checks to see if the doubly linked list is empty. If the linked list contains
  zero nodes, this function returns TRUE. Otherwise, it returns FALSE.

  If ListHead is NULL, then ASSERT().
  If ListHead was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or 
  InitializeListHead(), then ASSERT().
  If PcdMaximumLinkedListLenth is not zero, and the number of nodes
  in List, including the List node, is greater than or equal to
  PcdMaximumLinkedListLength, then ASSERT().

  @param  ListHead  A pointer to the head node of a doubly linked list.

  @retval TRUE  The linked list is empty.
  @retval FALSE The linked list is not empty.

**/
BOOLEAN
EFIAPI
IsListEmpty (
  IN      CONST LIST_ENTRY          *ListHead
  )
{
  //
  // ASSERT List not too long
  //
  ASSERT (IsNodeInList (ListHead, ListHead));

  return (BOOLEAN)(ListHead->ForwardLink == ListHead);
}

/**
  Determines if a node in a doubly linked list is the head node of a the same
  doubly linked list.  This function is typically used to terminate a loop that
  traverses all the nodes in a doubly linked list starting with the head node.

  Returns TRUE if Node is equal to List.  Returns FALSE if Node is one of the
  nodes in the doubly linked list specified by List.  List must have been
  initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead().

  If List is NULL, then ASSERT().
  If Node is NULL, then ASSERT().
  If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead(), 
  then ASSERT().
  If PcdMaximumLinkedListLenth is not zero, and the number of nodes
  in List, including the List node, is greater than or equal to
  PcdMaximumLinkedListLength, then ASSERT().
  If Node is not a node in List and Node is not equal to List, then ASSERT().

  @param  List  A pointer to the head node of a doubly linked list.
  @param  Node  A pointer to a node in the doubly linked list.

  @retval TRUE  Node is one of the nodes in the doubly linked list.
  @retval FALSE Node is not one of the nodes in the doubly linked list.

**/
BOOLEAN
EFIAPI
IsNull (
  IN      CONST LIST_ENTRY          *List,
  IN      CONST LIST_ENTRY          *Node
  )
{
  //
  // ASSERT List not too long and Node is one of the nodes of List
  //
  ASSERT (IsNodeInList (List, Node));

  return (BOOLEAN)(Node == List);
}

/**
  Determines if a node the last node in a doubly linked list.

  Returns TRUE if Node is the last node in the doubly linked list specified by
  List. Otherwise, FALSE is returned. List must have been initialized with
  INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead().

  If List is NULL, then ASSERT().
  If Node is NULL, then ASSERT().
  If List was not initialized with INTIALIZE_LIST_HEAD_VARIABLE() or
  InitializeListHead(), then ASSERT().
  If PcdMaximumLinkedListLenth is not zero, and the number of nodes
  in List, including the List node, is greater than or equal to
  PcdMaximumLinkedListLength, then ASSERT().
  If Node is not a node in List, then ASSERT().

  @param  List  A pointer to the head node of a doubly linked list.
  @param  Node  A pointer to a node in the doubly linked list.

  @retval TRUE  Node is the last node in the linked list.
  @retval FALSE Node is not the last node in the linked list.

**/
BOOLEAN
EFIAPI
IsNodeAtEnd (
  IN      CONST LIST_ENTRY          *List,
  IN      CONST LIST_ENTRY          *Node
  )
{
  //
  // ASSERT List not too long and Node is one of the nodes of List
  //
  ASSERT (IsNodeInList (List, Node));

  return (BOOLEAN)(!IsNull (List, Node) && List->BackLink == Node);
}

/**
  Swaps the location of two nodes in a doubly linked list, and returns the
  first node after the swap.

  If FirstEntry is identical to SecondEntry, then SecondEntry is returned.
  Otherwise, the location of the FirstEntry node is swapped with the location
  of the SecondEntry node in a doubly linked list. SecondEntry must be in the
  same double linked list as FirstEntry and that double linked list must have
  been initialized with INTIALIZE_LIST_HEAD_VARIABLE() or InitializeListHead(). 
  SecondEntry is returned after the nodes are swapped.

  If FirstEntry is NULL, then ASSERT().
  If SecondEntry is NULL, then ASSERT().
  If SecondEntry and FirstEntry are not in the same linked list, then ASSERT().
  If PcdMaximumLinkedListLength is not zero, and the number of nodes in the
  linked list containing the FirstEntry and SecondEntry nodes, including
  the FirstEntry and SecondEntry nodes, is greater than or equal to
  PcdMaximumLinkedListLength, then ASSERT().

  @param  FirstEntry  A pointer to a node in a linked list.
  @param  SecondEntry A pointer to another node in the same linked list.
  
  @return SecondEntry.

**/
LIST_ENTRY *
EFIAPI
SwapListEntries (
  IN OUT  LIST_ENTRY                *FirstEntry,
  IN OUT  LIST_ENTRY                *SecondEntry
  )
{
  LIST_ENTRY                    *Ptr;

  if (FirstEntry == SecondEntry) {
    return SecondEntry;
  }

  //
  // ASSERT Entry1 and Entry2 are in the same linked list
  //
  ASSERT (IsNodeInList (FirstEntry, SecondEntry));

  //
  // Ptr is the node pointed to by FirstEntry->ForwardLink
  //
  Ptr = RemoveEntryList (FirstEntry);

  //
  // If FirstEntry immediately follows SecondEntry, FirstEntry will be placed
  // immediately in front of SecondEntry
  //
  if (Ptr->BackLink == SecondEntry) {
    return InsertTailList (SecondEntry, FirstEntry);
  }

  //
  // Ptr == SecondEntry means SecondEntry immediately follows FirstEntry,
  // then there are no further steps necessary
  //
  if (Ptr == InsertHeadList (SecondEntry, FirstEntry)) {
    return Ptr;
  }

  //
  // Move SecondEntry to the front of Ptr
  //
  RemoveEntryList (SecondEntry);
  InsertTailList (Ptr, SecondEntry);
  return SecondEntry;
}

/**
  Removes a node from a doubly linked list, and returns the node that follows
  the removed node.

  Removes the node Entry from a doubly linked list. It is up to the caller of
  this function to release the memory used by this node if that is required. On
  exit, the node following Entry in the doubly linked list is returned. If
  Entry is the only node in the linked list, then the head node of the linked
  list is returned.

  If Entry is NULL, then ASSERT().
  If Entry is the head node of an empty list, then ASSERT().
  If PcdMaximumLinkedListLength is not zero, and the number of nodes in the
  linked list containing Entry, including the Entry node, is greater than
  or equal to PcdMaximumLinkedListLength, then ASSERT().

  @param  Entry A pointer to a node in a linked list.

  @return Entry.

**/
LIST_ENTRY *
EFIAPI
RemoveEntryList (
  IN      CONST LIST_ENTRY          *Entry
  )
{
  ASSERT (!IsListEmpty (Entry));

  Entry->ForwardLink->BackLink = Entry->BackLink;
  Entry->BackLink->ForwardLink = Entry->ForwardLink;
  return Entry->ForwardLink;
}