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 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 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 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 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 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 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 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 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 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 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 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 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
