asltree.c revision 1.12 1 /******************************************************************************
2 *
3 * Module Name: asltree - Parse tree management
4 *
5 *****************************************************************************/
6
7 /*
8 * Copyright (C) 2000 - 2018, Intel Corp.
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions, and the following disclaimer,
16 * without modification.
17 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18 * substantially similar to the "NO WARRANTY" disclaimer below
19 * ("Disclaimer") and any redistribution must be conditioned upon
20 * including a substantially similar Disclaimer requirement for further
21 * binary redistribution.
22 * 3. Neither the names of the above-listed copyright holders nor the names
23 * of any contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * Alternatively, this software may be distributed under the terms of the
27 * GNU General Public License ("GPL") version 2 as published by the Free
28 * Software Foundation.
29 *
30 * NO WARRANTY
31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41 * POSSIBILITY OF SUCH DAMAGES.
42 */
43
44 #include "aslcompiler.h"
45 #include "aslcompiler.y.h"
46 #include "acapps.h"
47
48 #define _COMPONENT ACPI_COMPILER
49 ACPI_MODULE_NAME ("asltree")
50
51
52 /*******************************************************************************
53 *
54 * FUNCTION: TrSetOpIntegerValue
55 *
56 * PARAMETERS: ParseOpcode - New opcode to be assigned to the op
57 * Op - An existing parse op
58 *
59 * RETURN: The updated op
60 *
61 * DESCRIPTION: Used to set the integer value of a op,
62 * usually to a specific size (8, 16, 32, or 64 bits)
63 *
64 ******************************************************************************/
65
66 ACPI_PARSE_OBJECT *
67 TrSetOpIntegerValue (
68 UINT32 ParseOpcode,
69 ACPI_PARSE_OBJECT *Op)
70 {
71
72 if (!Op)
73 {
74 return (NULL);
75 }
76
77 DbgPrint (ASL_PARSE_OUTPUT,
78 "\nUpdateOp: Old - %s, New - %s\n",
79 UtGetOpName (Op->Asl.ParseOpcode),
80 UtGetOpName (ParseOpcode));
81
82 /* Assign new opcode and name */
83
84 if (Op->Asl.ParseOpcode == PARSEOP_ONES)
85 {
86 switch (ParseOpcode)
87 {
88 case PARSEOP_BYTECONST:
89
90 Op->Asl.Value.Integer = ACPI_UINT8_MAX;
91 break;
92
93 case PARSEOP_WORDCONST:
94
95 Op->Asl.Value.Integer = ACPI_UINT16_MAX;
96 break;
97
98 case PARSEOP_DWORDCONST:
99
100 Op->Asl.Value.Integer = ACPI_UINT32_MAX;
101 break;
102
103 /* Don't need to do the QWORD case */
104
105 default:
106
107 /* Don't care about others */
108 break;
109 }
110 }
111
112 Op->Asl.ParseOpcode = (UINT16) ParseOpcode;
113 UtSetParseOpName (Op);
114
115 /*
116 * For the BYTE, WORD, and DWORD constants, make sure that the integer
117 * that was passed in will actually fit into the data type
118 */
119 switch (ParseOpcode)
120 {
121 case PARSEOP_BYTECONST:
122
123 UtCheckIntegerRange (Op, 0x00, ACPI_UINT8_MAX);
124 Op->Asl.Value.Integer &= ACPI_UINT8_MAX;
125 break;
126
127 case PARSEOP_WORDCONST:
128
129 UtCheckIntegerRange (Op, 0x00, ACPI_UINT16_MAX);
130 Op->Asl.Value.Integer &= ACPI_UINT16_MAX;
131 break;
132
133 case PARSEOP_DWORDCONST:
134
135 UtCheckIntegerRange (Op, 0x00, ACPI_UINT32_MAX);
136 Op->Asl.Value.Integer &= ACPI_UINT32_MAX;
137 break;
138
139 default:
140
141 /* Don't care about others, don't need to check QWORD */
142
143 break;
144 }
145
146 /* Converter: if this is a method invocation, turn off capture comments */
147
148 if (AcpiGbl_CaptureComments &&
149 (ParseOpcode == PARSEOP_METHODCALL))
150 {
151 Gbl_CommentState.CaptureComments = FALSE;
152 }
153
154 return (Op);
155 }
156
157
158 /*******************************************************************************
159 *
160 * FUNCTION: TrSetOpFlags
161 *
162 * PARAMETERS: Op - An existing parse op
163 * Flags - New flags word
164 *
165 * RETURN: The updated parser op
166 *
167 * DESCRIPTION: Set bits in the op flags word. Will not clear bits, only set
168 *
169 ******************************************************************************/
170
171 ACPI_PARSE_OBJECT *
172 TrSetOpFlags (
173 ACPI_PARSE_OBJECT *Op,
174 UINT32 Flags)
175 {
176
177 if (!Op)
178 {
179 return (NULL);
180 }
181
182 DbgPrint (ASL_PARSE_OUTPUT,
183 "\nSetOpFlags: %s Op %p, %8.8X", Op->Asl.ParseOpName, Op, Flags);
184
185 TrPrintOpFlags (Flags, ASL_PARSE_OUTPUT);
186 DbgPrint (ASL_PARSE_OUTPUT, "\n\n");
187
188 Op->Asl.CompileFlags |= Flags;
189 return (Op);
190 }
191
192
193 /*******************************************************************************
194 *
195 * FUNCTION: TrSetOpAmlLength
196 *
197 * PARAMETERS: Op - An existing parse op
198 * Length - AML Length
199 *
200 * RETURN: The updated parser op
201 *
202 * DESCRIPTION: Set the AML Length in a op. Used by the parser to indicate
203 * the presence of a op that must be reduced to a fixed length
204 * constant.
205 *
206 ******************************************************************************/
207
208 ACPI_PARSE_OBJECT *
209 TrSetOpAmlLength (
210 ACPI_PARSE_OBJECT *Op,
211 UINT32 Length)
212 {
213
214 DbgPrint (ASL_PARSE_OUTPUT,
215 "\nSetOpAmlLength: Op %p, %8.8X\n", Op, Length);
216
217 if (!Op)
218 {
219 return (NULL);
220 }
221
222 Op->Asl.AmlLength = Length;
223 return (Op);
224 }
225
226
227 /*******************************************************************************
228 *
229 * FUNCTION: TrSetOpParent
230 *
231 * PARAMETERS: Op - To be set to new parent
232 * ParentOp - The parent
233 *
234 * RETURN: None, sets Op parent directly
235 *
236 * DESCRIPTION: Change the parent of a parse op.
237 *
238 ******************************************************************************/
239
240 void
241 TrSetOpParent (
242 ACPI_PARSE_OBJECT *Op,
243 ACPI_PARSE_OBJECT *ParentOp)
244 {
245
246 Op->Asl.Parent = ParentOp;
247 }
248
249
250 /*******************************************************************************
251 *
252 * FUNCTION: TrSetOpCurrentFilename
253 *
254 * PARAMETERS: Op - An existing parse op
255 *
256 * RETURN: None
257 *
258 * DESCRIPTION: Save the include file filename. Used for debug output only.
259 *
260 ******************************************************************************/
261
262 void
263 TrSetOpCurrentFilename (
264 ACPI_PARSE_OBJECT *Op)
265 {
266
267 Op->Asl.Filename = Gbl_PreviousIncludeFilename;
268 }
269
270
271 /*******************************************************************************
272 *
273 * FUNCTION: TrSetOpIntegerWidth
274 *
275 * PARAMETERS: Op - An existing parse op
276 *
277 * RETURN: None
278 *
279 * DESCRIPTION:
280 *
281 ******************************************************************************/
282
283 void
284 TrSetOpIntegerWidth (
285 ACPI_PARSE_OBJECT *TableSignatureOp,
286 ACPI_PARSE_OBJECT *RevisionOp)
287 {
288
289 /* TBD: Check table sig? (DSDT vs. SSDT) */
290
291 /* Handle command-line version override */
292
293 if (Gbl_RevisionOverride)
294 {
295 AcpiUtSetIntegerWidth (Gbl_RevisionOverride);
296 }
297 else
298 {
299 AcpiUtSetIntegerWidth ((UINT8) RevisionOp->Asl.Value.Integer);
300 }
301 }
302
303
304 /*******************************************************************************
305 *
306 * FUNCTION: TrSetOpEndLineNumber
307 *
308 * PARAMETERS: Op - An existing parse op
309 *
310 * RETURN: None.
311 *
312 * DESCRIPTION: Set the ending line numbers (file line and logical line) of a
313 * parse op to the current line numbers.
314 *
315 ******************************************************************************/
316
317 void
318 TrSetOpEndLineNumber (
319 ACPI_PARSE_OBJECT *Op)
320 {
321
322 /* If the end line # is already set, just return */
323
324 if (Op->Asl.EndLine)
325 {
326 return;
327 }
328
329 Op->Asl.EndLine = Gbl_CurrentLineNumber;
330 Op->Asl.EndLogicalLine = Gbl_LogicalLineNumber;
331 }
332
333
334 /*******************************************************************************
335 *
336 * FUNCTION: TrLinkOpChildren
337 *
338 * PARAMETERS: Op - An existing parse op
339 * NumChildren - Number of children to follow
340 * ... - A list of child ops to link to the new
341 * op. NumChildren long.
342 *
343 * RETURN: The updated (linked) op
344 *
345 * DESCRIPTION: Link a group of ops to an existing parse op
346 *
347 ******************************************************************************/
348
349 ACPI_PARSE_OBJECT *
350 TrLinkOpChildren (
351 ACPI_PARSE_OBJECT *Op,
352 UINT32 NumChildren,
353 ...)
354 {
355 ACPI_PARSE_OBJECT *Child;
356 ACPI_PARSE_OBJECT *PrevChild;
357 va_list ap;
358 UINT32 i;
359 BOOLEAN FirstChild;
360
361
362 va_start (ap, NumChildren);
363
364 TrSetOpEndLineNumber (Op);
365
366 DbgPrint (ASL_PARSE_OUTPUT,
367 "\nLinkChildren Line [%u to %u] NewParent %p Child %u Op %s ",
368 Op->Asl.LineNumber, Op->Asl.EndLine,
369 Op, NumChildren, UtGetOpName(Op->Asl.ParseOpcode));
370
371 switch (Op->Asl.ParseOpcode)
372 {
373 case PARSEOP_ASL_CODE:
374
375 Gbl_ParseTreeRoot = Op;
376 Op->Asl.ParseOpcode = PARSEOP_DEFAULT_ARG;
377 DbgPrint (ASL_PARSE_OUTPUT, "ASLCODE (Tree Completed)->");
378 break;
379
380 case PARSEOP_DEFINITION_BLOCK:
381
382 DbgPrint (ASL_PARSE_OUTPUT, "DEFINITION_BLOCK (Tree Completed)->");
383 break;
384
385 case PARSEOP_OPERATIONREGION:
386
387 DbgPrint (ASL_PARSE_OUTPUT, "OPREGION->");
388 break;
389
390 case PARSEOP_OR:
391
392 DbgPrint (ASL_PARSE_OUTPUT, "OR->");
393 break;
394
395 default:
396
397 /* Nothing to do for other opcodes */
398
399 break;
400 }
401
402 /* The following is for capturing comments */
403
404 if (AcpiGbl_CaptureComments)
405 {
406 /*
407 * If there are "regular comments" detected at this point,
408 * then is an endBlk comment. Categorize it as so and distribute
409 * all regular comments to this parse op.
410 */
411 if (Gbl_CommentListHead)
412 {
413 Op->Asl.EndBlkComment = Gbl_CommentListHead;
414 CvDbgPrint ("EndBlk Comment for %s: %s",
415 Op->Asl.ParseOpName, Gbl_CommentListHead->Comment);
416 Gbl_CommentListHead = NULL;
417 Gbl_CommentListTail = NULL;
418 }
419 }
420
421 /* Link the new op to it's children */
422
423 PrevChild = NULL;
424 FirstChild = TRUE;
425 for (i = 0; i < NumChildren; i++)
426 {
427 Child = va_arg (ap, ACPI_PARSE_OBJECT *);
428
429 if ((Child == PrevChild) && (Child != NULL))
430 {
431 AslError (ASL_WARNING, ASL_MSG_COMPILER_INTERNAL, Child,
432 "Child op list invalid");
433 va_end(ap);
434 return (Op);
435 }
436
437 DbgPrint (ASL_PARSE_OUTPUT, "%p, ", Child);
438
439 /*
440 * If child is NULL, this means that an optional argument
441 * was omitted. We must create a placeholder with a special
442 * opcode (DEFAULT_ARG) so that the code generator will know
443 * that it must emit the correct default for this argument
444 */
445 if (!Child)
446 {
447 Child = TrAllocateOp (PARSEOP_DEFAULT_ARG);
448 }
449
450 /* Link first child to parent */
451
452 if (FirstChild)
453 {
454 FirstChild = FALSE;
455 Op->Asl.Child = Child;
456 }
457
458 /* Point all children to parent */
459
460 Child->Asl.Parent = Op;
461
462 /* Link children in a peer list */
463
464 if (PrevChild)
465 {
466 PrevChild->Asl.Next = Child;
467 }
468
469 /*
470 * This child might be a list, point all ops in the list
471 * to the same parent
472 */
473 while (Child->Asl.Next)
474 {
475 Child = Child->Asl.Next;
476 Child->Asl.Parent = Op;
477 }
478
479 PrevChild = Child;
480 }
481
482 va_end(ap);
483 DbgPrint (ASL_PARSE_OUTPUT, "\n\n");
484
485 if (AcpiGbl_CaptureComments)
486 {
487 Gbl_CommentState.LatestParseOp = Op;
488 CvDbgPrint ("TrLinkOpChildren=====Set latest parse op to this op.\n");
489 }
490
491 return (Op);
492 }
493
494
495 /*******************************************************************************
496 *
497 * FUNCTION: TrLinkPeerOp
498 *
499 * PARAMETERS: Op1 - First peer
500 * Op2 - Second peer
501 *
502 * RETURN: Op1 or the non-null op.
503 *
504 * DESCRIPTION: Link two ops as peers. Handles cases where one peer is null.
505 *
506 ******************************************************************************/
507
508 ACPI_PARSE_OBJECT *
509 TrLinkPeerOp (
510 ACPI_PARSE_OBJECT *Op1,
511 ACPI_PARSE_OBJECT *Op2)
512 {
513 ACPI_PARSE_OBJECT *Next;
514
515
516 DbgPrint (ASL_PARSE_OUTPUT,
517 "\nLinkPeerOp: 1=%p (%s), 2=%p (%s)\n",
518 Op1, Op1 ? UtGetOpName(Op1->Asl.ParseOpcode) : NULL,
519 Op2, Op2 ? UtGetOpName(Op2->Asl.ParseOpcode) : NULL);
520
521
522 if ((!Op1) && (!Op2))
523 {
524 DbgPrint (ASL_PARSE_OUTPUT, "\nTwo Null ops!\n");
525 return (Op1);
526 }
527
528 /* If one of the ops is null, just return the non-null op */
529
530 if (!Op2)
531 {
532 return (Op1);
533 }
534
535 if (!Op1)
536 {
537 return (Op2);
538 }
539
540 if (Op1 == Op2)
541 {
542 DbgPrint (ASL_DEBUG_OUTPUT,
543 "\n************* Internal error, linking op to itself %p\n",
544 Op1);
545 AslError (ASL_WARNING, ASL_MSG_COMPILER_INTERNAL, Op1,
546 "Linking op to itself");
547 return (Op1);
548 }
549
550 Op1->Asl.Parent = Op2->Asl.Parent;
551
552 /*
553 * Op 1 may already have a peer list (such as an IF/ELSE pair),
554 * so we must walk to the end of the list and attach the new
555 * peer at the end
556 */
557 Next = Op1;
558 while (Next->Asl.Next)
559 {
560 Next = Next->Asl.Next;
561 }
562
563 Next->Asl.Next = Op2;
564 return (Op1);
565 }
566
567
568 /*******************************************************************************
569 *
570 * FUNCTION: TrLinkPeerOps
571 *
572 * PARAMETERS: NumPeers - The number of ops in the list to follow
573 * ... - A list of ops to link together as peers
574 *
575 * RETURN: The first op in the list (head of the peer list)
576 *
577 * DESCRIPTION: Link together an arbitrary number of peer ops.
578 *
579 ******************************************************************************/
580
581 ACPI_PARSE_OBJECT *
582 TrLinkPeerOps (
583 UINT32 NumPeers,
584 ...)
585 {
586 ACPI_PARSE_OBJECT *This;
587 ACPI_PARSE_OBJECT *Next;
588 va_list ap;
589 UINT32 i;
590 ACPI_PARSE_OBJECT *Start;
591
592
593 DbgPrint (ASL_PARSE_OUTPUT,
594 "\nLinkPeerOps: (%u) ", NumPeers);
595
596 va_start (ap, NumPeers);
597 This = va_arg (ap, ACPI_PARSE_OBJECT *);
598 Start = This;
599
600 /*
601 * Link all peers
602 */
603 for (i = 0; i < (NumPeers -1); i++)
604 {
605 DbgPrint (ASL_PARSE_OUTPUT, "%u=%p ", (i+1), This);
606
607 while (This->Asl.Next)
608 {
609 This = This->Asl.Next;
610 }
611
612 /* Get another peer op */
613
614 Next = va_arg (ap, ACPI_PARSE_OBJECT *);
615 if (!Next)
616 {
617 Next = TrAllocateOp (PARSEOP_DEFAULT_ARG);
618 }
619
620 /* link new op to the current op */
621
622 This->Asl.Next = Next;
623 This = Next;
624 }
625
626 va_end (ap);
627 DbgPrint (ASL_PARSE_OUTPUT,"\n");
628 return (Start);
629 }
630
631
632 /*******************************************************************************
633 *
634 * FUNCTION: TrLinkChildOp
635 *
636 * PARAMETERS: Op1 - Parent op
637 * Op2 - Op to become a child
638 *
639 * RETURN: The parent op
640 *
641 * DESCRIPTION: Link two ops together as a parent and child
642 *
643 ******************************************************************************/
644
645 ACPI_PARSE_OBJECT *
646 TrLinkChildOp (
647 ACPI_PARSE_OBJECT *Op1,
648 ACPI_PARSE_OBJECT *Op2)
649 {
650 ACPI_PARSE_OBJECT *Next;
651
652
653 DbgPrint (ASL_PARSE_OUTPUT,
654 "\nLinkChildOp: Parent=%p (%s), Child=%p (%s)\n",
655 Op1, Op1 ? UtGetOpName(Op1->Asl.ParseOpcode): NULL,
656 Op2, Op2 ? UtGetOpName(Op2->Asl.ParseOpcode): NULL);
657
658 /*
659 * Converter: if TrLinkChildOp is called to link a method call,
660 * turn on capture comments as it signifies that we are done parsing
661 * a method call.
662 */
663 if (AcpiGbl_CaptureComments && Op1)
664 {
665 if (Op1->Asl.ParseOpcode == PARSEOP_METHODCALL)
666 {
667 Gbl_CommentState.CaptureComments = TRUE;
668 }
669 Gbl_CommentState.LatestParseOp = Op1;
670 }
671
672 if (!Op1 || !Op2)
673 {
674 return (Op1);
675 }
676
677 Op1->Asl.Child = Op2;
678
679 /* Set the child and all peers of the child to point to the parent */
680
681 Next = Op2;
682 while (Next)
683 {
684 Next->Asl.Parent = Op1;
685 Next = Next->Asl.Next;
686 }
687
688 return (Op1);
689 }
690
691
692 /*******************************************************************************
693 *
694 * FUNCTION: TrWalkParseTree
695 *
696 * PARAMETERS: Op - Walk starting point
697 * Visitation - Type of walk
698 * DescendingCallback - Called during tree descent
699 * AscendingCallback - Called during tree ascent
700 * Context - To be passed to the callbacks
701 *
702 * RETURN: Status from callback(s)
703 *
704 * DESCRIPTION: Walk the entire parse tree.
705 *
706 ******************************************************************************/
707
708 ACPI_STATUS
709 TrWalkParseTree (
710 ACPI_PARSE_OBJECT *Op,
711 UINT32 Visitation,
712 ASL_WALK_CALLBACK DescendingCallback,
713 ASL_WALK_CALLBACK AscendingCallback,
714 void *Context)
715 {
716 UINT32 Level;
717 BOOLEAN OpPreviouslyVisited;
718 ACPI_PARSE_OBJECT *StartOp = Op;
719 ACPI_STATUS Status;
720
721
722 if (!Gbl_ParseTreeRoot)
723 {
724 return (AE_OK);
725 }
726
727 Level = 0;
728 OpPreviouslyVisited = FALSE;
729
730 switch (Visitation)
731 {
732 case ASL_WALK_VISIT_DOWNWARD:
733
734 while (Op)
735 {
736 if (!OpPreviouslyVisited)
737 {
738 /* Let the callback process the op. */
739
740 Status = DescendingCallback (Op, Level, Context);
741 if (ACPI_SUCCESS (Status))
742 {
743 /* Visit children first, once */
744
745 if (Op->Asl.Child)
746 {
747 Level++;
748 Op = Op->Asl.Child;
749 continue;
750 }
751 }
752 else if (Status != AE_CTRL_DEPTH)
753 {
754 /* Exit immediately on any error */
755
756 return (Status);
757 }
758 }
759
760 /* Terminate walk at start op */
761
762 if (Op == StartOp)
763 {
764 break;
765 }
766
767 /* No more children, visit peers */
768
769 if (Op->Asl.Next)
770 {
771 Op = Op->Asl.Next;
772 OpPreviouslyVisited = FALSE;
773 }
774 else
775 {
776 /* No children or peers, re-visit parent */
777
778 if (Level != 0 )
779 {
780 Level--;
781 }
782 Op = Op->Asl.Parent;
783 OpPreviouslyVisited = TRUE;
784 }
785 }
786 break;
787
788 case ASL_WALK_VISIT_UPWARD:
789
790 while (Op)
791 {
792 /* Visit leaf op (no children) or parent op on return trip */
793
794 if ((!Op->Asl.Child) ||
795 (OpPreviouslyVisited))
796 {
797 /* Let the callback process the op. */
798
799 Status = AscendingCallback (Op, Level, Context);
800 if (ACPI_FAILURE (Status))
801 {
802 return (Status);
803 }
804 }
805 else
806 {
807 /* Visit children first, once */
808
809 Level++;
810 Op = Op->Asl.Child;
811 continue;
812 }
813
814 /* Terminate walk at start op */
815
816 if (Op == StartOp)
817 {
818 break;
819 }
820
821 /* No more children, visit peers */
822
823 if (Op->Asl.Next)
824 {
825 Op = Op->Asl.Next;
826 OpPreviouslyVisited = FALSE;
827 }
828 else
829 {
830 /* No children or peers, re-visit parent */
831
832 if (Level != 0 )
833 {
834 Level--;
835 }
836 Op = Op->Asl.Parent;
837 OpPreviouslyVisited = TRUE;
838 }
839 }
840 break;
841
842 case ASL_WALK_VISIT_TWICE:
843
844 while (Op)
845 {
846 if (OpPreviouslyVisited)
847 {
848 Status = AscendingCallback (Op, Level, Context);
849 if (ACPI_FAILURE (Status))
850 {
851 return (Status);
852 }
853 }
854 else
855 {
856 /* Let the callback process the op. */
857
858 Status = DescendingCallback (Op, Level, Context);
859 if (ACPI_SUCCESS (Status))
860 {
861 /* Visit children first, once */
862
863 if (Op->Asl.Child)
864 {
865 Level++;
866 Op = Op->Asl.Child;
867 continue;
868 }
869 }
870 else if (Status != AE_CTRL_DEPTH)
871 {
872 /* Exit immediately on any error */
873
874 return (Status);
875 }
876 }
877
878 /* Terminate walk at start op */
879
880 if (Op == StartOp)
881 {
882 break;
883 }
884
885 /* No more children, visit peers */
886
887 if (Op->Asl.Next)
888 {
889 Op = Op->Asl.Next;
890 OpPreviouslyVisited = FALSE;
891 }
892 else
893 {
894 /* No children or peers, re-visit parent */
895
896 if (Level != 0 )
897 {
898 Level--;
899 }
900 Op = Op->Asl.Parent;
901 OpPreviouslyVisited = TRUE;
902 }
903 }
904 break;
905
906 default:
907 /* No other types supported */
908 break;
909 }
910
911 /* If we get here, the walk completed with no errors */
912
913 return (AE_OK);
914 }
915