xref: /freebsd/sys/contrib/dev/acpica/compiler/aslexternal.c (revision 722b16673c40aedf280895f2f2f676bb494518d7)
1 /******************************************************************************
2  *
3  * Module Name: aslexternal - ASL External opcode compiler support
4  *
5  *****************************************************************************/
6 
7 /******************************************************************************
8  *
9  * 1. Copyright Notice
10  *
11  * Some or all of this work - Copyright (c) 1999 - 2023, Intel Corp.
12  * All rights reserved.
13  *
14  * 2. License
15  *
16  * 2.1. This is your license from Intel Corp. under its intellectual property
17  * rights. You may have additional license terms from the party that provided
18  * you this software, covering your right to use that party's intellectual
19  * property rights.
20  *
21  * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
22  * copy of the source code appearing in this file ("Covered Code") an
23  * irrevocable, perpetual, worldwide license under Intel's copyrights in the
24  * base code distributed originally by Intel ("Original Intel Code") to copy,
25  * make derivatives, distribute, use and display any portion of the Covered
26  * Code in any form, with the right to sublicense such rights; and
27  *
28  * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
29  * license (with the right to sublicense), under only those claims of Intel
30  * patents that are infringed by the Original Intel Code, to make, use, sell,
31  * offer to sell, and import the Covered Code and derivative works thereof
32  * solely to the minimum extent necessary to exercise the above copyright
33  * license, and in no event shall the patent license extend to any additions
34  * to or modifications of the Original Intel Code. No other license or right
35  * is granted directly or by implication, estoppel or otherwise;
36  *
37  * The above copyright and patent license is granted only if the following
38  * conditions are met:
39  *
40  * 3. Conditions
41  *
42  * 3.1. Redistribution of Source with Rights to Further Distribute Source.
43  * Redistribution of source code of any substantial portion of the Covered
44  * Code or modification with rights to further distribute source must include
45  * the above Copyright Notice, the above License, this list of Conditions,
46  * and the following Disclaimer and Export Compliance provision. In addition,
47  * Licensee must cause all Covered Code to which Licensee contributes to
48  * contain a file documenting the changes Licensee made to create that Covered
49  * Code and the date of any change. Licensee must include in that file the
50  * documentation of any changes made by any predecessor Licensee. Licensee
51  * must include a prominent statement that the modification is derived,
52  * directly or indirectly, from Original Intel Code.
53  *
54  * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
55  * Redistribution of source code of any substantial portion of the Covered
56  * Code or modification without rights to further distribute source must
57  * include the following Disclaimer and Export Compliance provision in the
58  * documentation and/or other materials provided with distribution. In
59  * addition, Licensee may not authorize further sublicense of source of any
60  * portion of the Covered Code, and must include terms to the effect that the
61  * license from Licensee to its licensee is limited to the intellectual
62  * property embodied in the software Licensee provides to its licensee, and
63  * not to intellectual property embodied in modifications its licensee may
64  * make.
65  *
66  * 3.3. Redistribution of Executable. Redistribution in executable form of any
67  * substantial portion of the Covered Code or modification must reproduce the
68  * above Copyright Notice, and the following Disclaimer and Export Compliance
69  * provision in the documentation and/or other materials provided with the
70  * distribution.
71  *
72  * 3.4. Intel retains all right, title, and interest in and to the Original
73  * Intel Code.
74  *
75  * 3.5. Neither the name Intel nor any other trademark owned or controlled by
76  * Intel shall be used in advertising or otherwise to promote the sale, use or
77  * other dealings in products derived from or relating to the Covered Code
78  * without prior written authorization from Intel.
79  *
80  * 4. Disclaimer and Export Compliance
81  *
82  * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
83  * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
84  * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
85  * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
86  * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
87  * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
88  * PARTICULAR PURPOSE.
89  *
90  * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
91  * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
92  * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
93  * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
94  * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
95  * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
96  * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
97  * LIMITED REMEDY.
98  *
99  * 4.3. Licensee shall not export, either directly or indirectly, any of this
100  * software or system incorporating such software without first obtaining any
101  * required license or other approval from the U. S. Department of Commerce or
102  * any other agency or department of the United States Government. In the
103  * event Licensee exports any such software from the United States or
104  * re-exports any such software from a foreign destination, Licensee shall
105  * ensure that the distribution and export/re-export of the software is in
106  * compliance with all laws, regulations, orders, or other restrictions of the
107  * U.S. Export Administration Regulations. Licensee agrees that neither it nor
108  * any of its subsidiaries will export/re-export any technical data, process,
109  * software, or service, directly or indirectly, to any country for which the
110  * United States government or any agency thereof requires an export license,
111  * other governmental approval, or letter of assurance, without first obtaining
112  * such license, approval or letter.
113  *
114  *****************************************************************************
115  *
116  * Alternatively, you may choose to be licensed under the terms of the
117  * following license:
118  *
119  * Redistribution and use in source and binary forms, with or without
120  * modification, are permitted provided that the following conditions
121  * are met:
122  * 1. Redistributions of source code must retain the above copyright
123  *    notice, this list of conditions, and the following disclaimer,
124  *    without modification.
125  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
126  *    substantially similar to the "NO WARRANTY" disclaimer below
127  *    ("Disclaimer") and any redistribution must be conditioned upon
128  *    including a substantially similar Disclaimer requirement for further
129  *    binary redistribution.
130  * 3. Neither the names of the above-listed copyright holders nor the names
131  *    of any contributors may be used to endorse or promote products derived
132  *    from this software without specific prior written permission.
133  *
134  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
135  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
136  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
137  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
138  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
139  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
140  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
141  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
142  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
143  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
144  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
145  *
146  * Alternatively, you may choose to be licensed under the terms of the
147  * GNU General Public License ("GPL") version 2 as published by the Free
148  * Software Foundation.
149  *
150  *****************************************************************************/
151 
152 #include <contrib/dev/acpica/compiler/aslcompiler.h>
153 #include "aslcompiler.y.h"
154 #include <contrib/dev/acpica/include/acparser.h>
155 #include <contrib/dev/acpica/include/amlcode.h>
156 #include <contrib/dev/acpica/include/acnamesp.h>
157 
158 
159 #define _COMPONENT          ACPI_COMPILER
160         ACPI_MODULE_NAME    ("aslexternal")
161 
162 
163 /* Local prototypes */
164 
165 static void
166 ExInsertArgCount (
167     ACPI_PARSE_OBJECT       *Op);
168 
169 static void
170 ExMoveExternals (
171     ACPI_PARSE_OBJECT       *DefinitionBlockOp);
172 
173 
174 /*******************************************************************************
175  *
176  * FUNCTION:    ExDoExternal
177  *
178  * PARAMETERS:  Op                  - Current Parse node
179  *
180  * RETURN:      None
181  *
182  * DESCRIPTION: Add an External() definition to the global list. This list
183  *              is used to generate External opcodes.
184  *
185  ******************************************************************************/
186 
187 void
ExDoExternal(ACPI_PARSE_OBJECT * Op)188 ExDoExternal (
189     ACPI_PARSE_OBJECT       *Op)
190 {
191     ACPI_PARSE_OBJECT       *ListOp;
192     ACPI_PARSE_OBJECT       *Prev;
193     ACPI_PARSE_OBJECT       *Next;
194     ACPI_PARSE_OBJECT       *ArgCountOp;
195     ACPI_PARSE_OBJECT       *TypeOp;
196     ACPI_PARSE_OBJECT       *ExternTypeOp = Op->Asl.Child->Asl.Next;
197     UINT32                  ExternType;
198     UINT8                   ParamCount = ASL_EXTERNAL_METHOD_UNKNOWN_PARAMS;
199     UINT32                  ParamTypes[ACPI_METHOD_NUM_ARGS];
200 
201 
202     ExternType = AnMapObjTypeToBtype (ExternTypeOp);
203     if (ExternType != ACPI_BTYPE_METHOD)
204     {
205         /*
206          * If this is not a method, it has zero parameters this local variable
207          * is used only for methods
208          */
209         ParamCount = 0;
210     }
211 
212     /*
213      * The parser allows optional parameter return types regardless of the
214      * type. Check object type keyword emit error if optional parameter/return
215      * types exist.
216      *
217      * Check the parameter return type
218      */
219     TypeOp = ExternTypeOp->Asl.Next;
220     if (TypeOp->Asl.Child)
221     {
222         /* Ignore the return type for now. */
223 
224         (void) MtProcessTypeOp (TypeOp->Asl.Child);
225         if (ExternType != ACPI_BTYPE_METHOD)
226         {
227             sprintf (AslGbl_MsgBuffer, "Found type [%s]", AcpiUtGetTypeName(ExternType));
228             AslError (ASL_ERROR, ASL_MSG_EXTERN_INVALID_RET_TYPE, TypeOp,
229                 AslGbl_MsgBuffer);
230         }
231     }
232 
233     /* Check the parameter types */
234 
235     TypeOp = TypeOp->Asl.Next;
236     if (TypeOp->Asl.Child)
237     {
238         ParamCount = MtProcessParameterTypeList (TypeOp->Asl.Child, ParamTypes);
239         if (ExternType != ACPI_BTYPE_METHOD)
240         {
241             sprintf (AslGbl_MsgBuffer, "Found type [%s]", AcpiUtGetTypeName(ExternType));
242             AslError (ASL_ERROR, ASL_MSG_EXTERN_INVALID_PARAM_TYPE, TypeOp,
243                 AslGbl_MsgBuffer);
244         }
245     }
246 
247     ArgCountOp = Op->Asl.Child->Asl.Next->Asl.Next;
248     ArgCountOp->Asl.AmlOpcode = AML_RAW_DATA_BYTE;
249     ArgCountOp->Asl.ParseOpcode = PARSEOP_BYTECONST;
250     ArgCountOp->Asl.Value.Integer = ParamCount;
251     UtSetParseOpName (ArgCountOp);
252 
253     /* Create new list node of arbitrary type */
254 
255     ListOp = TrAllocateOp (PARSEOP_DEFAULT_ARG);
256 
257     /* Store External node as child */
258 
259     ListOp->Asl.Child = Op;
260     ListOp->Asl.Next = NULL;
261 
262     if (AslGbl_ExternalsListHead)
263     {
264         /* Link new External to end of list */
265 
266         Prev = AslGbl_ExternalsListHead;
267         Next = Prev;
268         while (Next)
269         {
270             Prev = Next;
271             Next = Next->Asl.Next;
272         }
273 
274         Prev->Asl.Next = ListOp;
275     }
276     else
277     {
278         AslGbl_ExternalsListHead = ListOp;
279     }
280 }
281 
282 
283 /*******************************************************************************
284  *
285  * FUNCTION:    ExInsertArgCount
286  *
287  * PARAMETERS:  Op              - Op for a method invocation
288  *
289  * RETURN:      None
290  *
291  * DESCRIPTION: Obtain the number of arguments for a control method -- from
292  *              the actual invocation.
293  *
294  ******************************************************************************/
295 
296 static void
ExInsertArgCount(ACPI_PARSE_OBJECT * Op)297 ExInsertArgCount (
298     ACPI_PARSE_OBJECT       *Op)
299 {
300     ACPI_PARSE_OBJECT       *Next;
301     ACPI_PARSE_OBJECT       *NameOp;
302     ACPI_PARSE_OBJECT       *Child;
303     ACPI_PARSE_OBJECT       *ArgCountOp;
304     char *                  ExternalName;
305     char *                  CallName;
306     UINT16                  ArgCount = 0;
307     ACPI_STATUS             Status;
308 
309 
310     CallName = AcpiNsGetNormalizedPathname (Op->Asl.Node, TRUE);
311 
312     Next = AslGbl_ExternalsListHead;
313     while (Next)
314     {
315         ArgCount = 0;
316 
317         /* Skip if External node already handled */
318 
319         if (Next->Asl.Child->Asl.CompileFlags & OP_VISITED)
320         {
321             Next = Next->Asl.Next;
322             continue;
323         }
324 
325         NameOp = Next->Asl.Child->Asl.Child;
326         ExternalName = AcpiNsGetNormalizedPathname (NameOp->Asl.Node, TRUE);
327 
328         if (strcmp (CallName, ExternalName))
329         {
330             ACPI_FREE (ExternalName);
331             Next = Next->Asl.Next;
332             continue;
333         }
334 
335         Next->Asl.Child->Asl.CompileFlags |= OP_VISITED;
336 
337         /*
338          * Since we will reposition Externals to the Root, set Namepath
339          * to the fully qualified name and recalculate the aml length
340          */
341         Status = UtInternalizeName (ExternalName,
342             &NameOp->Asl.Value.String);
343 
344         ACPI_FREE (ExternalName);
345         if (ACPI_FAILURE (Status))
346         {
347             AslError (ASL_ERROR, ASL_MSG_COMPILER_INTERNAL,
348                 NULL, "- Could not Internalize External");
349             break;
350         }
351 
352         NameOp->Asl.AmlLength = strlen (NameOp->Asl.Value.String);
353 
354         /* Get argument count */
355 
356         Child = Op->Asl.Child;
357         while (Child)
358         {
359             ArgCount++;
360             Child = Child->Asl.Next;
361         }
362 
363         /* Setup ArgCount operand */
364 
365         ArgCountOp = Next->Asl.Child->Asl.Child->Asl.Next->Asl.Next;
366         ArgCountOp->Asl.Value.Integer = ArgCount;
367         break;
368     }
369 
370     ACPI_FREE (CallName);
371 }
372 
373 
374 /*******************************************************************************
375  *
376  * FUNCTION:    ExAmlExternalWalkBegin
377  *
378  * PARAMETERS:  ASL_WALK_CALLBACK
379  *
380  * RETURN:      None
381  *
382  * DESCRIPTION: Parse tree walk to create external opcode list for methods.
383  *
384  ******************************************************************************/
385 
386 ACPI_STATUS
ExAmlExternalWalkBegin(ACPI_PARSE_OBJECT * Op,UINT32 Level,void * Context)387 ExAmlExternalWalkBegin (
388     ACPI_PARSE_OBJECT       *Op,
389     UINT32                  Level,
390     void                    *Context)
391 {
392 
393     /* External list head saved in the definition block op */
394 
395     if (Op->Asl.ParseOpcode == PARSEOP_DEFINITION_BLOCK)
396     {
397         AslGbl_ExternalsListHead = Op->Asl.Value.Arg;
398     }
399 
400     if (!AslGbl_ExternalsListHead)
401     {
402         return (AE_OK);
403     }
404 
405     if (Op->Asl.ParseOpcode != PARSEOP_METHODCALL)
406     {
407         return (AE_OK);
408     }
409 
410     /*
411      * The NameOp child under an ExternalOp gets turned into PARSE_METHODCALL
412      * by XfNamespaceLocateBegin(). Ignore these.
413      */
414     if (Op->Asl.Parent &&
415         Op->Asl.Parent->Asl.ParseOpcode == PARSEOP_EXTERNAL)
416     {
417         return (AE_OK);
418     }
419 
420     ExInsertArgCount (Op);
421     return (AE_OK);
422 }
423 
424 
425 /*******************************************************************************
426  *
427  * FUNCTION:    ExAmlExternalWalkEnd
428  *
429  * PARAMETERS:  ASL_WALK_CALLBACK
430  *
431  * RETURN:      None
432  *
433  * DESCRIPTION: Parse tree walk to create external opcode list for methods.
434  *              Here, we just want to catch the case where a definition block
435  *              has been completed. Then we move all of the externals into
436  *              a single block in the parse tree and thus the AML code.
437  *
438  ******************************************************************************/
439 
440 ACPI_STATUS
ExAmlExternalWalkEnd(ACPI_PARSE_OBJECT * Op,UINT32 Level,void * Context)441 ExAmlExternalWalkEnd (
442     ACPI_PARSE_OBJECT       *Op,
443     UINT32                  Level,
444     void                    *Context)
445 {
446 
447     if (Op->Asl.ParseOpcode == PARSEOP_DEFINITION_BLOCK)
448     {
449         /*
450          * Process any existing external list. (Support for
451          * multiple definition blocks in a single file/compile)
452          */
453         ExMoveExternals (Op);
454         AslGbl_ExternalsListHead = NULL;
455     }
456 
457     return (AE_OK);
458 }
459 
460 
461 /*******************************************************************************
462  *
463  * FUNCTION:    ExMoveExternals
464  *
465  * PARAMETERS:  DefinitionBlockOp       - Op for current definition block
466  *
467  * RETURN:      None
468  *
469  * DESCRIPTION: Move all externals present in the source file into a single
470  *              block of AML code, surrounded by an "If (0)" to prevent
471  *              AML interpreters from attempting to execute the External
472  *              opcodes.
473  *
474  ******************************************************************************/
475 
476 static void
ExMoveExternals(ACPI_PARSE_OBJECT * DefinitionBlockOp)477 ExMoveExternals (
478     ACPI_PARSE_OBJECT       *DefinitionBlockOp)
479 {
480     ACPI_PARSE_OBJECT       *ParentOp;
481     ACPI_PARSE_OBJECT       *ExternalOp;
482     ACPI_PARSE_OBJECT       *PredicateOp;
483     ACPI_PARSE_OBJECT       *NextOp;
484     ACPI_PARSE_OBJECT       *Prev;
485     ACPI_PARSE_OBJECT       *Next;
486     char                    *ExternalName;
487     ACPI_OBJECT_TYPE        ObjType;
488     ACPI_STATUS             Status;
489     UINT32                  i;
490 
491 
492     if (!AslGbl_ExternalsListHead)
493     {
494         return;
495     }
496 
497     /* Remove the External nodes from the tree */
498 
499     NextOp = AslGbl_ExternalsListHead;
500     while (NextOp)
501     {
502         /*
503          * The External is stored in child pointer of each node in the
504          * list
505          */
506         ExternalOp = NextOp->Asl.Child;
507 
508         /* Get/set the fully qualified name */
509 
510         ExternalName = AcpiNsGetNormalizedPathname (ExternalOp->Asl.Node, TRUE);
511         ExternalOp->Asl.ExternalName = ExternalName;
512         ExternalOp->Asl.Namepath = ExternalName;
513 
514         /* Set line numbers (for listings, etc.) */
515 
516         ExternalOp->Asl.LineNumber = 0;
517         ExternalOp->Asl.LogicalLineNumber = 0;
518 
519         Next = ExternalOp->Asl.Child;
520         Next->Asl.LineNumber = 0;
521         Next->Asl.LogicalLineNumber = 0;
522 
523         if (Next->Asl.ParseOpcode == PARSEOP_NAMESEG)
524         {
525             Next->Asl.ParseOpcode = PARSEOP_NAMESTRING;
526         }
527 
528         Next->Asl.ExternalName = ExternalName;
529         Status = UtInternalizeName (ExternalName, &Next->Asl.Value.String);
530         if (ACPI_FAILURE (Status))
531         {
532             AslError (ASL_ERROR, ASL_MSG_COMPILER_INTERNAL,
533                 Next, "Could not internalize namestring");
534             return;
535         }
536 
537         Next->Asl.AmlLength = strlen (Next->Asl.Value.String);
538 
539         Next = Next->Asl.Next;
540         Next->Asl.LineNumber = 0;
541         Next->Asl.LogicalLineNumber = 0;
542 
543         Next = Next->Asl.Next;
544         Next->Asl.LineNumber = 0;
545         Next->Asl.LogicalLineNumber = 0;
546 
547         Next = Next->Asl.Next;
548         Next->Asl.LineNumber = 0;
549         Next->Asl.LogicalLineNumber = 0;
550 
551         ParentOp = ExternalOp->Asl.Parent;
552         Prev = Next = ParentOp->Asl.Child;
553 
554         /* Now find the External node's position in parse tree */
555 
556         while (Next != ExternalOp)
557         {
558             Prev = Next;
559             Next = Next->Asl.Next;
560         }
561 
562         /* Remove the External from the parse tree */
563 
564         if (Prev == ExternalOp)
565         {
566             /* External was the first child node */
567 
568             ParentOp->Asl.Child = ExternalOp->Asl.Next;
569         }
570 
571         Prev->Asl.Next = ExternalOp->Asl.Next;
572         ExternalOp->Asl.Next = NULL;
573         ExternalOp->Asl.Parent = AslGbl_ExternalsListHead;
574 
575         /* Point the External to the next in the list */
576 
577         if (NextOp->Asl.Next)
578         {
579             ExternalOp->Asl.Next = NextOp->Asl.Next->Asl.Child;
580         }
581 
582         NextOp = NextOp->Asl.Next;
583     }
584 
585     /*
586      * Loop again to remove MethodObj Externals for which
587      * a MethodCall was not found (dead external reference)
588      */
589     Prev = AslGbl_ExternalsListHead->Asl.Child;
590     Next = Prev;
591     while (Next)
592     {
593         ObjType = (ACPI_OBJECT_TYPE)
594             Next->Asl.Child->Asl.Next->Asl.Value.Integer;
595 
596         if (ObjType == ACPI_TYPE_METHOD &&
597             !(Next->Asl.CompileFlags & OP_VISITED))
598         {
599             if (Next == Prev)
600             {
601                 AslGbl_ExternalsListHead->Asl.Child = Next->Asl.Next;
602                 Next->Asl.Next = NULL;
603                 Prev = AslGbl_ExternalsListHead->Asl.Child;
604                 Next = Prev;
605                 continue;
606             }
607             else
608             {
609                 Prev->Asl.Next = Next->Asl.Next;
610                 Next->Asl.Next = NULL;
611                 Next = Prev->Asl.Next;
612                 continue;
613             }
614         }
615 
616         Prev = Next;
617         Next = Next->Asl.Next;
618     }
619 
620     /* If list is now empty, don't bother to make If (0) block */
621 
622     if (!AslGbl_ExternalsListHead->Asl.Child)
623     {
624         return;
625     }
626 
627     /* Convert Gbl_ExternalsListHead parent to If(). */
628 
629     AslGbl_ExternalsListHead->Asl.ParseOpcode = PARSEOP_IF;
630     AslGbl_ExternalsListHead->Asl.AmlOpcode = AML_IF_OP;
631     AslGbl_ExternalsListHead->Asl.CompileFlags = OP_AML_PACKAGE;
632     UtSetParseOpName (AslGbl_ExternalsListHead);
633 
634     /* Create a Zero op for the If predicate */
635 
636     PredicateOp = TrAllocateOp (PARSEOP_ZERO);
637     PredicateOp->Asl.AmlOpcode = AML_ZERO_OP;
638 
639     PredicateOp->Asl.Parent = AslGbl_ExternalsListHead;
640     PredicateOp->Asl.Child = NULL;
641     PredicateOp->Asl.Next = AslGbl_ExternalsListHead->Asl.Child;
642     AslGbl_ExternalsListHead->Asl.Child = PredicateOp;
643 
644     /* Set line numbers (for listings, etc.) */
645 
646     AslGbl_ExternalsListHead->Asl.LineNumber = 0;
647     AslGbl_ExternalsListHead->Asl.LogicalLineNumber = 0;
648 
649     PredicateOp->Asl.LineNumber = 0;
650     PredicateOp->Asl.LogicalLineNumber = 0;
651 
652     /* Insert block back in the list */
653 
654     Prev = DefinitionBlockOp->Asl.Child;
655     Next = Prev;
656 
657     /* Find last default arg */
658 
659     for (i = 0; i < 6; i++)
660     {
661         Prev = Next;
662         Next = Prev->Asl.Next;
663     }
664 
665     if (Next)
666     {
667         /* Definition Block is not empty */
668 
669         AslGbl_ExternalsListHead->Asl.Next = Next;
670     }
671     else
672     {
673         /* Definition Block is empty. */
674 
675         AslGbl_ExternalsListHead->Asl.Next = NULL;
676     }
677 
678     Prev->Asl.Next = AslGbl_ExternalsListHead;
679     AslGbl_ExternalsListHead->Asl.Parent = Prev->Asl.Parent;
680 }
681