xref: /netbsd-src/sys/external/bsd/acpica/dist/compiler/dtutils.c (revision e670fd5c413e99c2f6a37901bb21c537fcd322d2)
1 /******************************************************************************
2  *
3  * Module Name: dtutils.c - Utility routines for the data table compiler
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2021, 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 MERCHANTABILITY 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 "actables.h"
46 
47 #define _COMPONENT          DT_COMPILER
48         ACPI_MODULE_NAME    ("dtutils")
49 
50 /* Local prototypes */
51 
52 static void
53 DtSum (
54     DT_SUBTABLE             *Subtable,
55     void                    *Context,
56     void                    *ReturnValue);
57 
58 
59 /******************************************************************************
60  *
61  * FUNCTION:    DtError
62  *
63  * PARAMETERS:  Level               - Seriousness (Warning/error, etc.)
64  *              MessageId           - Index into global message buffer
65  *              Op                  - Parse node where error happened
66  *              ExtraMessage        - additional error message
67  *
68  * RETURN:      None
69  *
70  * DESCRIPTION: Common error interface for data table compiler
71  *
72  *****************************************************************************/
73 
74 void
75 DtError (
76     UINT8                   Level,
77     UINT16                  MessageId,
78     DT_FIELD                *FieldObject,
79     char                    *ExtraMessage)
80 {
81     UINT32                  Line = 0;
82 
83 
84     /* Field object could be NULL */
85 
86     if (FieldObject)
87     {
88         Line = FieldObject->Line;
89     }
90 
91     /* Check if user wants to ignore this exception */
92 
93     if (AslIsExceptionIgnored (AslGbl_Files[ASL_FILE_INPUT].Filename,
94         Line, Level, MessageId))
95     {
96         return;
97     }
98 
99     if (FieldObject)
100     {
101         AslCommonError (Level, MessageId,
102             FieldObject->Line,
103             FieldObject->Line,
104             FieldObject->ByteOffset,
105             FieldObject->Column,
106             AslGbl_Files[ASL_FILE_INPUT].Filename, ExtraMessage);
107     }
108     else
109     {
110         AslCommonError (Level, MessageId, 0,
111             0, 0, 0, 0, ExtraMessage);
112     }
113 }
114 
115 
116 /******************************************************************************
117  *
118  * FUNCTION:    DtNameError
119  *
120  * PARAMETERS:  Level               - Seriousness (Warning/error, etc.)
121  *              MessageId           - Index into global message buffer
122  *              Op                  - Parse node where error happened
123  *              ExtraMessage        - additional error message
124  *
125  * RETURN:      None
126  *
127  * DESCRIPTION: Error interface for named objects
128  *
129  *****************************************************************************/
130 
131 void
132 DtNameError (
133     UINT8                   Level,
134     UINT16                  MessageId,
135     DT_FIELD                *FieldObject,
136     char                    *ExtraMessage)
137 {
138 
139     switch (Level)
140     {
141     case ASL_WARNING2:
142     case ASL_WARNING3:
143 
144         if (AslGbl_WarningLevel < Level)
145         {
146             return;
147         }
148         break;
149 
150     default:
151 
152         break;
153     }
154 
155     if (FieldObject)
156     {
157         AslCommonError (Level, MessageId,
158             FieldObject->Line,
159             FieldObject->Line,
160             FieldObject->ByteOffset,
161             FieldObject->NameColumn,
162             AslGbl_Files[ASL_FILE_INPUT].Filename, ExtraMessage);
163     }
164     else
165     {
166         AslCommonError (Level, MessageId, 0,
167             0, 0, 0, 0, ExtraMessage);
168     }
169 }
170 
171 
172 /*******************************************************************************
173  *
174  * FUNCTION:    DtFatal
175  *
176  * PARAMETERS:  None
177  *
178  * RETURN:      None
179  *
180  * DESCRIPTION: Dump the error log and abort the compiler. Used for serious
181  *              compile or I/O errors
182  *
183  ******************************************************************************/
184 
185 void
186 DtFatal (
187     UINT16                  MessageId,
188     DT_FIELD                *FieldObject,
189     char                    *ExtraMessage)
190 {
191 
192     DtError (ASL_ERROR, MessageId, FieldObject, ExtraMessage);
193 
194 /*
195  * TBD: remove this entire function, DtFatal
196  *
197  * We cannot abort the compiler on error, because we may be compiling a
198  * list of files. We must move on to the next file.
199  */
200 #ifdef __OBSOLETE
201     CmCleanupAndExit ();
202     exit (1);
203 #endif
204 }
205 
206 
207 /*******************************************************************************
208  *
209  * FUNCTION:    DtDoConstant
210  *
211  * PARAMETERS:  String              - Only hex constants are supported,
212  *                                    regardless of whether the 0x prefix
213  *                                    is used
214  *
215  * RETURN:      Converted Integer
216  *
217  * DESCRIPTION: Convert a string to an integer, with overflow/error checking.
218  *
219  ******************************************************************************/
220 
221 UINT64
222 DtDoConstant (
223     char                    *String)
224 {
225     UINT64                  ConvertedInteger;
226 
227 
228     /*
229      * TBD: The ImplicitStrtoul64 function does not report overflow
230      * conditions. The input string is simply truncated. If it is
231      * desired to report overflow to the table compiler, this should
232      * somehow be added here. Note: integers that are prefixed with 0x
233      * or not are both hex integers.
234      */
235     ConvertedInteger = AcpiUtImplicitStrtoul64 (String);
236     return (ConvertedInteger);
237 }
238 
239 /******************************************************************************
240  *
241  * FUNCTION:    DtGetFieldValue
242  *
243  * PARAMETERS:  Field               - Current field list pointer
244  *
245  * RETURN:      Field value
246  *
247  * DESCRIPTION: Get field value
248  *
249  *****************************************************************************/
250 
251 char *
252 DtGetFieldValue (
253     DT_FIELD                *Field)
254 {
255     if (!Field)
256     {
257         return (NULL);
258     }
259 
260     return (Field->Value);
261 }
262 
263 
264 /******************************************************************************
265  *
266  * FUNCTION:    DtGetFieldType
267  *
268  * PARAMETERS:  Info                - Data table info
269  *
270  * RETURN:      Field type
271  *
272  * DESCRIPTION: Get field type
273  *
274  *****************************************************************************/
275 
276 UINT8
277 DtGetFieldType (
278     ACPI_DMTABLE_INFO       *Info)
279 {
280     UINT8                   Type;
281 
282 
283     /* DT_FLAG means that this is the start of a block of flag bits */
284     /* TBD - we can make these a separate opcode later */
285 
286     if (Info->Flags & DT_FLAG)
287     {
288         return (DT_FIELD_TYPE_FLAGS_INTEGER);
289     }
290 
291     /* Type is based upon the opcode for this field in the info table */
292 
293     switch (Info->Opcode)
294     {
295     case ACPI_DMT_FLAG0:
296     case ACPI_DMT_FLAG1:
297     case ACPI_DMT_FLAG2:
298     case ACPI_DMT_FLAG3:
299     case ACPI_DMT_FLAG4:
300     case ACPI_DMT_FLAG5:
301     case ACPI_DMT_FLAG6:
302     case ACPI_DMT_FLAG7:
303     case ACPI_DMT_FLAGS0:
304     case ACPI_DMT_FLAGS1:
305     case ACPI_DMT_FLAGS2:
306     case ACPI_DMT_FLAGS4:
307     case ACPI_DMT_FLAGS4_0:
308     case ACPI_DMT_FLAGS4_4:
309     case ACPI_DMT_FLAGS4_8:
310     case ACPI_DMT_FLAGS4_12:
311     case ACPI_DMT_FLAGS16_16:
312 
313         Type = DT_FIELD_TYPE_FLAG;
314         break;
315 
316     case ACPI_DMT_NAME4:
317     case ACPI_DMT_SIG:
318     case ACPI_DMT_NAME6:
319     case ACPI_DMT_NAME8:
320     case ACPI_DMT_STRING:
321     case ACPI_DMT_IVRS_UNTERMINATED_STRING:
322 
323         Type = DT_FIELD_TYPE_STRING;
324         break;
325 
326     case ACPI_DMT_BUFFER:
327     case ACPI_DMT_RAW_BUFFER:
328     case ACPI_DMT_BUF7:
329     case ACPI_DMT_BUF10:
330     case ACPI_DMT_BUF12:
331     case ACPI_DMT_BUF16:
332     case ACPI_DMT_BUF128:
333     case ACPI_DMT_PCI_PATH:
334     case ACPI_DMT_PMTT_VENDOR:
335 
336         Type = DT_FIELD_TYPE_BUFFER;
337         break;
338 
339     case ACPI_DMT_GAS:
340     case ACPI_DMT_HESTNTFY:
341     case ACPI_DMT_IORTMEM:
342 
343         Type = DT_FIELD_TYPE_INLINE_SUBTABLE;
344         break;
345 
346     case ACPI_DMT_UNICODE:
347 
348         Type = DT_FIELD_TYPE_UNICODE;
349         break;
350 
351     case ACPI_DMT_UUID:
352 
353         Type = DT_FIELD_TYPE_UUID;
354         break;
355 
356     case ACPI_DMT_DEVICE_PATH:
357 
358         Type = DT_FIELD_TYPE_DEVICE_PATH;
359         break;
360 
361     case ACPI_DMT_LABEL:
362 
363         Type = DT_FIELD_TYPE_LABEL;
364         break;
365 
366     default:
367 
368         Type = DT_FIELD_TYPE_INTEGER;
369         break;
370     }
371 
372     return (Type);
373 }
374 
375 
376 /******************************************************************************
377  *
378  * FUNCTION:    DtGetBufferLength
379  *
380  * PARAMETERS:  Buffer              - List of integers,
381  *                                    for example "10 3A 4F 2E"
382  *
383  * RETURN:      Count of integer
384  *
385  * DESCRIPTION: Get length of bytes needed to store the integers
386  *
387  *****************************************************************************/
388 
389 UINT32
390 DtGetBufferLength (
391     char                    *Buffer)
392 {
393     UINT32                  ByteLength = 0;
394 
395 
396     while (*Buffer)
397     {
398         if (*Buffer == ' ')
399         {
400             ByteLength++;
401 
402             while (*Buffer == ' ')
403             {
404                 Buffer++;
405             }
406         }
407 
408         Buffer++;
409     }
410 
411     return (++ByteLength);
412 }
413 
414 
415 /******************************************************************************
416  *
417  * FUNCTION:    DtGetFieldLength
418  *
419  * PARAMETERS:  Field               - Current field
420  *              Info                - Data table info
421  *
422  * RETURN:      Field length
423  *
424  * DESCRIPTION: Get length of bytes needed to compile the field
425  *
426  * Note: This function must remain in sync with AcpiDmDumpTable.
427  *
428  *****************************************************************************/
429 
430 UINT32
431 DtGetFieldLength (
432     DT_FIELD                *Field,
433     ACPI_DMTABLE_INFO       *Info)
434 {
435     UINT32                  ByteLength = 0;
436     char                    *Value;
437 
438 
439     /* Length is based upon the opcode for this field in the info table */
440 
441     switch (Info->Opcode)
442     {
443     case ACPI_DMT_FLAG0:
444     case ACPI_DMT_FLAG1:
445     case ACPI_DMT_FLAG2:
446     case ACPI_DMT_FLAG3:
447     case ACPI_DMT_FLAG4:
448     case ACPI_DMT_FLAG5:
449     case ACPI_DMT_FLAG6:
450     case ACPI_DMT_FLAG7:
451     case ACPI_DMT_FLAGS0:
452     case ACPI_DMT_FLAGS1:
453     case ACPI_DMT_FLAGS2:
454     case ACPI_DMT_FLAGS4:
455     case ACPI_DMT_FLAGS4_0:
456     case ACPI_DMT_FLAGS4_4:
457     case ACPI_DMT_FLAGS4_8:
458     case ACPI_DMT_FLAGS4_12:
459     case ACPI_DMT_FLAGS16_16:
460     case ACPI_DMT_LABEL:
461     case ACPI_DMT_EXTRA_TEXT:
462 
463         ByteLength = 0;
464         break;
465 
466     case ACPI_DMT_UINT8:
467     case ACPI_DMT_CHKSUM:
468     case ACPI_DMT_SPACEID:
469     case ACPI_DMT_ACCWIDTH:
470     case ACPI_DMT_CEDT:
471     case ACPI_DMT_IVRS:
472     case ACPI_DMT_IVRS_DE:
473     case ACPI_DMT_GTDT:
474     case ACPI_DMT_MADT:
475     case ACPI_DMT_PCCT:
476     case ACPI_DMT_PMTT:
477     case ACPI_DMT_PPTT:
478     case ACPI_DMT_RGRT:
479     case ACPI_DMT_SDEV:
480     case ACPI_DMT_SRAT:
481     case ACPI_DMT_ASF:
482     case ACPI_DMT_HESTNTYP:
483     case ACPI_DMT_FADTPM:
484     case ACPI_DMT_EINJACT:
485     case ACPI_DMT_EINJINST:
486     case ACPI_DMT_ERSTACT:
487     case ACPI_DMT_ERSTINST:
488     case ACPI_DMT_DMAR_SCOPE:
489     case ACPI_DMT_VIOT:
490 
491         ByteLength = 1;
492         break;
493 
494     case ACPI_DMT_UINT16:
495     case ACPI_DMT_DMAR:
496     case ACPI_DMT_HEST:
497     case ACPI_DMT_HMAT:
498     case ACPI_DMT_NFIT:
499     case ACPI_DMT_PCI_PATH:
500     case ACPI_DMT_PHAT:
501 
502         ByteLength = 2;
503         break;
504 
505     case ACPI_DMT_UINT24:
506 
507         ByteLength = 3;
508         break;
509 
510     case ACPI_DMT_UINT32:
511     case ACPI_DMT_NAME4:
512     case ACPI_DMT_SIG:
513     case ACPI_DMT_LPIT:
514     case ACPI_DMT_TPM2:
515 
516         ByteLength = 4;
517         break;
518 
519     case ACPI_DMT_UINT40:
520 
521         ByteLength = 5;
522         break;
523 
524     case ACPI_DMT_UINT48:
525     case ACPI_DMT_NAME6:
526 
527         ByteLength = 6;
528         break;
529 
530     case ACPI_DMT_UINT56:
531     case ACPI_DMT_BUF7:
532 
533         ByteLength = 7;
534         break;
535 
536     case ACPI_DMT_UINT64:
537     case ACPI_DMT_NAME8:
538 
539         ByteLength = 8;
540         break;
541 
542     case ACPI_DMT_STRING:
543 
544         Value = DtGetFieldValue (Field);
545         if (Value)
546         {
547             ByteLength = strlen (Value) + 1;
548         }
549         else
550         {   /* At this point, this is a fatal error */
551 
552             snprintf (AslGbl_MsgBuffer, sizeof(AslGbl_MsgBuffer), "Expected \"%s\"", Info->Name);
553             DtFatal (ASL_MSG_COMPILER_INTERNAL, NULL, AslGbl_MsgBuffer);
554             return (0);
555         }
556         break;
557 
558     case ACPI_DMT_IVRS_UNTERMINATED_STRING:
559 
560         Value = DtGetFieldValue (Field);
561         if (Value)
562         {
563             ByteLength = strlen (Value);
564         }
565         else
566         {   /* At this point, this is a fatal error */
567 
568             sprintf (AslGbl_MsgBuffer, "Expected \"%s\"", Info->Name);
569             DtFatal (ASL_MSG_COMPILER_INTERNAL, NULL, AslGbl_MsgBuffer);
570             return (0);
571         }
572         break;
573 
574     case ACPI_DMT_GAS:
575 
576         ByteLength = sizeof (ACPI_GENERIC_ADDRESS);
577         break;
578 
579     case ACPI_DMT_HESTNTFY:
580 
581         ByteLength = sizeof (ACPI_HEST_NOTIFY);
582         break;
583 
584     case ACPI_DMT_IORTMEM:
585 
586         ByteLength = sizeof (ACPI_IORT_MEMORY_ACCESS);
587         break;
588 
589     case ACPI_DMT_BUFFER:
590     case ACPI_DMT_RAW_BUFFER:
591     case ACPI_DMT_PMTT_VENDOR:
592 
593         Value = DtGetFieldValue (Field);
594         if (Value)
595         {
596             ByteLength = DtGetBufferLength (Value);
597         }
598         else
599         {   /* At this point, this is a fatal error */
600 
601             snprintf (AslGbl_MsgBuffer, sizeof(AslGbl_MsgBuffer), "Expected \"%s\"", Info->Name);
602             DtFatal (ASL_MSG_COMPILER_INTERNAL, NULL, AslGbl_MsgBuffer);
603             return (0);
604         }
605         break;
606 
607     case ACPI_DMT_BUF10:
608 
609         ByteLength = 10;
610         break;
611 
612     case ACPI_DMT_BUF12:
613 
614         ByteLength = 12;
615         break;
616 
617     case ACPI_DMT_BUF16:
618     case ACPI_DMT_UUID:
619 
620         ByteLength = 16;
621         break;
622 
623     case ACPI_DMT_BUF128:
624 
625         ByteLength = 128;
626         break;
627 
628     case ACPI_DMT_UNICODE:
629 
630         Value = DtGetFieldValue (Field);
631 
632         /* TBD: error if Value is NULL? (as below?) */
633 
634         ByteLength = (strlen (Value) + 1) * sizeof(UINT16);
635         break;
636 
637     default:
638 
639         DtFatal (ASL_MSG_COMPILER_INTERNAL, Field, "Invalid table opcode");
640         return (0);
641     }
642 
643     return (ByteLength);
644 }
645 
646 
647 /******************************************************************************
648  *
649  * FUNCTION:    DtSum
650  *
651  * PARAMETERS:  DT_WALK_CALLBACK:
652  *              Subtable            - Subtable
653  *              Context             - Unused
654  *              ReturnValue         - Store the checksum of subtable
655  *
656  * RETURN:      Status
657  *
658  * DESCRIPTION: Get the checksum of subtable
659  *
660  *****************************************************************************/
661 
662 static void
663 DtSum (
664     DT_SUBTABLE             *Subtable,
665     void                    *Context,
666     void                    *ReturnValue)
667 {
668     UINT8                   Checksum;
669     UINT8                   *Sum = ReturnValue;
670 
671 
672     Checksum = AcpiTbChecksum (Subtable->Buffer, Subtable->Length);
673     *Sum = (UINT8) (*Sum + Checksum);
674 }
675 
676 
677 /******************************************************************************
678  *
679  * FUNCTION:    DtSetTableChecksum
680  *
681  * PARAMETERS:  ChecksumPointer     - Where to return the checksum
682  *
683  * RETURN:      None
684  *
685  * DESCRIPTION: Set checksum of the whole data table into the checksum field
686  *
687  *****************************************************************************/
688 
689 void
690 DtSetTableChecksum (
691     UINT8                   *ChecksumPointer)
692 {
693     UINT8                   Checksum = 0;
694     UINT8                   OldSum;
695 
696 
697     DtWalkTableTree (AslGbl_RootTable, DtSum, NULL, &Checksum);
698 
699     OldSum = *ChecksumPointer;
700     Checksum = (UINT8) (Checksum - OldSum);
701 
702     /* Compute the final checksum */
703 
704     Checksum = (UINT8) (0 - Checksum);
705     *ChecksumPointer = Checksum;
706 }
707 
708 
709 /******************************************************************************
710  *
711  * FUNCTION:    DtSetTableLength
712  *
713  * PARAMETERS:  None
714  *
715  * RETURN:      None
716  *
717  * DESCRIPTION: Walk the subtables and set all the length fields
718  *
719  *****************************************************************************/
720 
721 void
722 DtSetTableLength (
723     void)
724 {
725     DT_SUBTABLE             *ParentTable;
726     DT_SUBTABLE             *ChildTable;
727 
728 
729     ParentTable = AslGbl_RootTable;
730     ChildTable = NULL;
731 
732     if (!ParentTable)
733     {
734         return;
735     }
736 
737     DtSetSubtableLength (ParentTable);
738 
739     while (1)
740     {
741         ChildTable = DtGetNextSubtable (ParentTable, ChildTable);
742         if (ChildTable)
743         {
744             if (ChildTable->LengthField)
745             {
746                 DtSetSubtableLength (ChildTable);
747             }
748 
749             if (ChildTable->Child)
750             {
751                 ParentTable = ChildTable;
752                 ChildTable = NULL;
753             }
754             else
755             {
756                 ParentTable->TotalLength += ChildTable->TotalLength;
757                 if (ParentTable->LengthField)
758                 {
759                     DtSetSubtableLength (ParentTable);
760                 }
761             }
762         }
763         else
764         {
765             ChildTable = ParentTable;
766 
767             if (ChildTable == AslGbl_RootTable)
768             {
769                 break;
770             }
771 
772             ParentTable = DtGetParentSubtable (ParentTable);
773 
774             ParentTable->TotalLength += ChildTable->TotalLength;
775             if (ParentTable->LengthField)
776             {
777                 DtSetSubtableLength (ParentTable);
778             }
779         }
780     }
781 }
782 
783 
784 /******************************************************************************
785  *
786  * FUNCTION:    DtWalkTableTree
787  *
788  * PARAMETERS:  StartTable          - Subtable in the tree where walking begins
789  *              UserFunction        - Called during the walk
790  *              Context             - Passed to user function
791  *              ReturnValue         - The return value of UserFunction
792  *
793  * RETURN:      None
794  *
795  * DESCRIPTION: Performs a depth-first walk of the subtable tree
796  *
797  *****************************************************************************/
798 
799 void
800 DtWalkTableTree (
801     DT_SUBTABLE             *StartTable,
802     DT_WALK_CALLBACK        UserFunction,
803     void                    *Context,
804     void                    *ReturnValue)
805 {
806     DT_SUBTABLE             *ParentTable;
807     DT_SUBTABLE             *ChildTable;
808 
809 
810     ParentTable = StartTable;
811     ChildTable = NULL;
812 
813     if (!ParentTable)
814     {
815         return;
816     }
817 
818     UserFunction (ParentTable, Context, ReturnValue);
819 
820     while (1)
821     {
822         ChildTable = DtGetNextSubtable (ParentTable, ChildTable);
823         if (ChildTable)
824         {
825             UserFunction (ChildTable, Context, ReturnValue);
826 
827             if (ChildTable->Child)
828             {
829                 ParentTable = ChildTable;
830                 ChildTable = NULL;
831             }
832         }
833         else
834         {
835             ChildTable = ParentTable;
836             if (ChildTable == AslGbl_RootTable)
837             {
838                 break;
839             }
840 
841             ParentTable = DtGetParentSubtable (ParentTable);
842 
843             if (ChildTable->Peer == StartTable)
844             {
845                 break;
846             }
847         }
848     }
849 }
850