xref: /freebsd/sys/contrib/dev/acpica/components/executer/exmisc.c (revision b740c88bfb6453416926271c089262e7164dace3)
1 /******************************************************************************
2  *
3  * Module Name: exmisc - ACPI AML (p-code) execution - specific opcodes
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2015, 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 <contrib/dev/acpica/include/acpi.h>
45 #include <contrib/dev/acpica/include/accommon.h>
46 #include <contrib/dev/acpica/include/acinterp.h>
47 #include <contrib/dev/acpica/include/amlcode.h>
48 #include <contrib/dev/acpica/include/amlresrc.h>
49 
50 
51 #define _COMPONENT          ACPI_EXECUTER
52         ACPI_MODULE_NAME    ("exmisc")
53 
54 
55 /*******************************************************************************
56  *
57  * FUNCTION:    AcpiExGetObjectReference
58  *
59  * PARAMETERS:  ObjDesc             - Create a reference to this object
60  *              ReturnDesc          - Where to store the reference
61  *              WalkState           - Current state
62  *
63  * RETURN:      Status
64  *
65  * DESCRIPTION: Obtain and return a "reference" to the target object
66  *              Common code for the RefOfOp and the CondRefOfOp.
67  *
68  ******************************************************************************/
69 
70 ACPI_STATUS
71 AcpiExGetObjectReference (
72     ACPI_OPERAND_OBJECT     *ObjDesc,
73     ACPI_OPERAND_OBJECT     **ReturnDesc,
74     ACPI_WALK_STATE         *WalkState)
75 {
76     ACPI_OPERAND_OBJECT     *ReferenceObj;
77     ACPI_OPERAND_OBJECT     *ReferencedObj;
78 
79 
80     ACPI_FUNCTION_TRACE_PTR (ExGetObjectReference, ObjDesc);
81 
82 
83     *ReturnDesc = NULL;
84 
85     switch (ACPI_GET_DESCRIPTOR_TYPE (ObjDesc))
86     {
87     case ACPI_DESC_TYPE_OPERAND:
88 
89         if (ObjDesc->Common.Type != ACPI_TYPE_LOCAL_REFERENCE)
90         {
91             return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
92         }
93 
94         /*
95          * Must be a reference to a Local or Arg
96          */
97         switch (ObjDesc->Reference.Class)
98         {
99         case ACPI_REFCLASS_LOCAL:
100         case ACPI_REFCLASS_ARG:
101         case ACPI_REFCLASS_DEBUG:
102 
103             /* The referenced object is the pseudo-node for the local/arg */
104 
105             ReferencedObj = ObjDesc->Reference.Object;
106             break;
107 
108         default:
109 
110             ACPI_ERROR ((AE_INFO, "Unknown Reference Class 0x%2.2X",
111                 ObjDesc->Reference.Class));
112             return_ACPI_STATUS (AE_AML_INTERNAL);
113         }
114         break;
115 
116     case ACPI_DESC_TYPE_NAMED:
117         /*
118          * A named reference that has already been resolved to a Node
119          */
120         ReferencedObj = ObjDesc;
121         break;
122 
123     default:
124 
125         ACPI_ERROR ((AE_INFO, "Invalid descriptor type 0x%X",
126             ACPI_GET_DESCRIPTOR_TYPE (ObjDesc)));
127         return_ACPI_STATUS (AE_TYPE);
128     }
129 
130 
131     /* Create a new reference object */
132 
133     ReferenceObj = AcpiUtCreateInternalObject (ACPI_TYPE_LOCAL_REFERENCE);
134     if (!ReferenceObj)
135     {
136         return_ACPI_STATUS (AE_NO_MEMORY);
137     }
138 
139     ReferenceObj->Reference.Class = ACPI_REFCLASS_REFOF;
140     ReferenceObj->Reference.Object = ReferencedObj;
141     *ReturnDesc = ReferenceObj;
142 
143     ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
144         "Object %p Type [%s], returning Reference %p\n",
145         ObjDesc, AcpiUtGetObjectTypeName (ObjDesc), *ReturnDesc));
146 
147     return_ACPI_STATUS (AE_OK);
148 }
149 
150 
151 /*******************************************************************************
152  *
153  * FUNCTION:    AcpiExConcatTemplate
154  *
155  * PARAMETERS:  Operand0            - First source object
156  *              Operand1            - Second source object
157  *              ActualReturnDesc    - Where to place the return object
158  *              WalkState           - Current walk state
159  *
160  * RETURN:      Status
161  *
162  * DESCRIPTION: Concatenate two resource templates
163  *
164  ******************************************************************************/
165 
166 ACPI_STATUS
167 AcpiExConcatTemplate (
168     ACPI_OPERAND_OBJECT     *Operand0,
169     ACPI_OPERAND_OBJECT     *Operand1,
170     ACPI_OPERAND_OBJECT     **ActualReturnDesc,
171     ACPI_WALK_STATE         *WalkState)
172 {
173     ACPI_STATUS             Status;
174     ACPI_OPERAND_OBJECT     *ReturnDesc;
175     UINT8                   *NewBuf;
176     UINT8                   *EndTag;
177     ACPI_SIZE               Length0;
178     ACPI_SIZE               Length1;
179     ACPI_SIZE               NewLength;
180 
181 
182     ACPI_FUNCTION_TRACE (ExConcatTemplate);
183 
184 
185     /*
186      * Find the EndTag descriptor in each resource template.
187      * Note1: returned pointers point TO the EndTag, not past it.
188      * Note2: zero-length buffers are allowed; treated like one EndTag
189      */
190 
191     /* Get the length of the first resource template */
192 
193     Status = AcpiUtGetResourceEndTag (Operand0, &EndTag);
194     if (ACPI_FAILURE (Status))
195     {
196         return_ACPI_STATUS (Status);
197     }
198 
199     Length0 = ACPI_PTR_DIFF (EndTag, Operand0->Buffer.Pointer);
200 
201     /* Get the length of the second resource template */
202 
203     Status = AcpiUtGetResourceEndTag (Operand1, &EndTag);
204     if (ACPI_FAILURE (Status))
205     {
206         return_ACPI_STATUS (Status);
207     }
208 
209     Length1 = ACPI_PTR_DIFF (EndTag, Operand1->Buffer.Pointer);
210 
211     /* Combine both lengths, minimum size will be 2 for EndTag */
212 
213     NewLength = Length0 + Length1 + sizeof (AML_RESOURCE_END_TAG);
214 
215     /* Create a new buffer object for the result (with one EndTag) */
216 
217     ReturnDesc = AcpiUtCreateBufferObject (NewLength);
218     if (!ReturnDesc)
219     {
220         return_ACPI_STATUS (AE_NO_MEMORY);
221     }
222 
223     /*
224      * Copy the templates to the new buffer, 0 first, then 1 follows. One
225      * EndTag descriptor is copied from Operand1.
226      */
227     NewBuf = ReturnDesc->Buffer.Pointer;
228     ACPI_MEMCPY (NewBuf, Operand0->Buffer.Pointer, Length0);
229     ACPI_MEMCPY (NewBuf + Length0, Operand1->Buffer.Pointer, Length1);
230 
231     /* Insert EndTag and set the checksum to zero, means "ignore checksum" */
232 
233     NewBuf[NewLength - 1] = 0;
234     NewBuf[NewLength - 2] = ACPI_RESOURCE_NAME_END_TAG | 1;
235 
236     /* Return the completed resource template */
237 
238     *ActualReturnDesc = ReturnDesc;
239     return_ACPI_STATUS (AE_OK);
240 }
241 
242 
243 /*******************************************************************************
244  *
245  * FUNCTION:    AcpiExDoConcatenate
246  *
247  * PARAMETERS:  Operand0            - First source object
248  *              Operand1            - Second source object
249  *              ActualReturnDesc    - Where to place the return object
250  *              WalkState           - Current walk state
251  *
252  * RETURN:      Status
253  *
254  * DESCRIPTION: Concatenate two objects OF THE SAME TYPE.
255  *
256  ******************************************************************************/
257 
258 ACPI_STATUS
259 AcpiExDoConcatenate (
260     ACPI_OPERAND_OBJECT     *Operand0,
261     ACPI_OPERAND_OBJECT     *Operand1,
262     ACPI_OPERAND_OBJECT     **ActualReturnDesc,
263     ACPI_WALK_STATE         *WalkState)
264 {
265     ACPI_OPERAND_OBJECT     *LocalOperand1 = Operand1;
266     ACPI_OPERAND_OBJECT     *ReturnDesc;
267     char                    *NewBuf;
268     ACPI_STATUS             Status;
269 
270 
271     ACPI_FUNCTION_TRACE (ExDoConcatenate);
272 
273 
274     /*
275      * Convert the second operand if necessary. The first operand
276      * determines the type of the second operand, (See the Data Types
277      * section of the ACPI specification.)  Both object types are
278      * guaranteed to be either Integer/String/Buffer by the operand
279      * resolution mechanism.
280      */
281     switch (Operand0->Common.Type)
282     {
283     case ACPI_TYPE_INTEGER:
284 
285         Status = AcpiExConvertToInteger (Operand1, &LocalOperand1, 16);
286         break;
287 
288     case ACPI_TYPE_STRING:
289 
290         Status = AcpiExConvertToString (Operand1, &LocalOperand1,
291                     ACPI_IMPLICIT_CONVERT_HEX);
292         break;
293 
294     case ACPI_TYPE_BUFFER:
295 
296         Status = AcpiExConvertToBuffer (Operand1, &LocalOperand1);
297         break;
298 
299     default:
300 
301         ACPI_ERROR ((AE_INFO, "Invalid object type: 0x%X",
302             Operand0->Common.Type));
303         Status = AE_AML_INTERNAL;
304     }
305 
306     if (ACPI_FAILURE (Status))
307     {
308         goto Cleanup;
309     }
310 
311     /*
312      * Both operands are now known to be the same object type
313      * (Both are Integer, String, or Buffer), and we can now perform the
314      * concatenation.
315      */
316 
317     /*
318      * There are three cases to handle:
319      *
320      * 1) Two Integers concatenated to produce a new Buffer
321      * 2) Two Strings concatenated to produce a new String
322      * 3) Two Buffers concatenated to produce a new Buffer
323      */
324     switch (Operand0->Common.Type)
325     {
326     case ACPI_TYPE_INTEGER:
327 
328         /* Result of two Integers is a Buffer */
329         /* Need enough buffer space for two integers */
330 
331         ReturnDesc = AcpiUtCreateBufferObject ((ACPI_SIZE)
332                             ACPI_MUL_2 (AcpiGbl_IntegerByteWidth));
333         if (!ReturnDesc)
334         {
335             Status = AE_NO_MEMORY;
336             goto Cleanup;
337         }
338 
339         NewBuf = (char *) ReturnDesc->Buffer.Pointer;
340 
341         /* Copy the first integer, LSB first */
342 
343         ACPI_MEMCPY (NewBuf, &Operand0->Integer.Value,
344                         AcpiGbl_IntegerByteWidth);
345 
346         /* Copy the second integer (LSB first) after the first */
347 
348         ACPI_MEMCPY (NewBuf + AcpiGbl_IntegerByteWidth,
349                         &LocalOperand1->Integer.Value,
350                         AcpiGbl_IntegerByteWidth);
351         break;
352 
353     case ACPI_TYPE_STRING:
354 
355         /* Result of two Strings is a String */
356 
357         ReturnDesc = AcpiUtCreateStringObject (
358                         ((ACPI_SIZE) Operand0->String.Length +
359                         LocalOperand1->String.Length));
360         if (!ReturnDesc)
361         {
362             Status = AE_NO_MEMORY;
363             goto Cleanup;
364         }
365 
366         NewBuf = ReturnDesc->String.Pointer;
367 
368         /* Concatenate the strings */
369 
370         ACPI_STRCPY (NewBuf, Operand0->String.Pointer);
371         ACPI_STRCPY (NewBuf + Operand0->String.Length,
372                         LocalOperand1->String.Pointer);
373         break;
374 
375     case ACPI_TYPE_BUFFER:
376 
377         /* Result of two Buffers is a Buffer */
378 
379         ReturnDesc = AcpiUtCreateBufferObject (
380                         ((ACPI_SIZE) Operand0->Buffer.Length +
381                         LocalOperand1->Buffer.Length));
382         if (!ReturnDesc)
383         {
384             Status = AE_NO_MEMORY;
385             goto Cleanup;
386         }
387 
388         NewBuf = (char *) ReturnDesc->Buffer.Pointer;
389 
390         /* Concatenate the buffers */
391 
392         ACPI_MEMCPY (NewBuf, Operand0->Buffer.Pointer,
393                         Operand0->Buffer.Length);
394         ACPI_MEMCPY (NewBuf + Operand0->Buffer.Length,
395                         LocalOperand1->Buffer.Pointer,
396                         LocalOperand1->Buffer.Length);
397         break;
398 
399     default:
400 
401         /* Invalid object type, should not happen here */
402 
403         ACPI_ERROR ((AE_INFO, "Invalid object type: 0x%X",
404             Operand0->Common.Type));
405         Status =AE_AML_INTERNAL;
406         goto Cleanup;
407     }
408 
409     *ActualReturnDesc = ReturnDesc;
410 
411 Cleanup:
412     if (LocalOperand1 != Operand1)
413     {
414         AcpiUtRemoveReference (LocalOperand1);
415     }
416     return_ACPI_STATUS (Status);
417 }
418 
419 
420 /*******************************************************************************
421  *
422  * FUNCTION:    AcpiExDoMathOp
423  *
424  * PARAMETERS:  Opcode              - AML opcode
425  *              Integer0            - Integer operand #0
426  *              Integer1            - Integer operand #1
427  *
428  * RETURN:      Integer result of the operation
429  *
430  * DESCRIPTION: Execute a math AML opcode. The purpose of having all of the
431  *              math functions here is to prevent a lot of pointer dereferencing
432  *              to obtain the operands.
433  *
434  ******************************************************************************/
435 
436 UINT64
437 AcpiExDoMathOp (
438     UINT16                  Opcode,
439     UINT64                  Integer0,
440     UINT64                  Integer1)
441 {
442 
443     ACPI_FUNCTION_ENTRY ();
444 
445 
446     switch (Opcode)
447     {
448     case AML_ADD_OP:                /* Add (Integer0, Integer1, Result) */
449 
450         return (Integer0 + Integer1);
451 
452     case AML_BIT_AND_OP:            /* And (Integer0, Integer1, Result) */
453 
454         return (Integer0 & Integer1);
455 
456     case AML_BIT_NAND_OP:           /* NAnd (Integer0, Integer1, Result) */
457 
458         return (~(Integer0 & Integer1));
459 
460     case AML_BIT_OR_OP:             /* Or (Integer0, Integer1, Result) */
461 
462         return (Integer0 | Integer1);
463 
464     case AML_BIT_NOR_OP:            /* NOr (Integer0, Integer1, Result) */
465 
466         return (~(Integer0 | Integer1));
467 
468     case AML_BIT_XOR_OP:            /* XOr (Integer0, Integer1, Result) */
469 
470         return (Integer0 ^ Integer1);
471 
472     case AML_MULTIPLY_OP:           /* Multiply (Integer0, Integer1, Result) */
473 
474         return (Integer0 * Integer1);
475 
476     case AML_SHIFT_LEFT_OP:         /* ShiftLeft (Operand, ShiftCount, Result)*/
477 
478         /*
479          * We need to check if the shiftcount is larger than the integer bit
480          * width since the behavior of this is not well-defined in the C language.
481          */
482         if (Integer1 >= AcpiGbl_IntegerBitWidth)
483         {
484             return (0);
485         }
486         return (Integer0 << Integer1);
487 
488     case AML_SHIFT_RIGHT_OP:        /* ShiftRight (Operand, ShiftCount, Result) */
489 
490         /*
491          * We need to check if the shiftcount is larger than the integer bit
492          * width since the behavior of this is not well-defined in the C language.
493          */
494         if (Integer1 >= AcpiGbl_IntegerBitWidth)
495         {
496             return (0);
497         }
498         return (Integer0 >> Integer1);
499 
500     case AML_SUBTRACT_OP:           /* Subtract (Integer0, Integer1, Result) */
501 
502         return (Integer0 - Integer1);
503 
504     default:
505 
506         return (0);
507     }
508 }
509 
510 
511 /*******************************************************************************
512  *
513  * FUNCTION:    AcpiExDoLogicalNumericOp
514  *
515  * PARAMETERS:  Opcode              - AML opcode
516  *              Integer0            - Integer operand #0
517  *              Integer1            - Integer operand #1
518  *              LogicalResult       - TRUE/FALSE result of the operation
519  *
520  * RETURN:      Status
521  *
522  * DESCRIPTION: Execute a logical "Numeric" AML opcode. For these Numeric
523  *              operators (LAnd and LOr), both operands must be integers.
524  *
525  *              Note: cleanest machine code seems to be produced by the code
526  *              below, rather than using statements of the form:
527  *                  Result = (Integer0 && Integer1);
528  *
529  ******************************************************************************/
530 
531 ACPI_STATUS
532 AcpiExDoLogicalNumericOp (
533     UINT16                  Opcode,
534     UINT64                  Integer0,
535     UINT64                  Integer1,
536     BOOLEAN                 *LogicalResult)
537 {
538     ACPI_STATUS             Status = AE_OK;
539     BOOLEAN                 LocalResult = FALSE;
540 
541 
542     ACPI_FUNCTION_TRACE (ExDoLogicalNumericOp);
543 
544 
545     switch (Opcode)
546     {
547     case AML_LAND_OP:               /* LAnd (Integer0, Integer1) */
548 
549         if (Integer0 && Integer1)
550         {
551             LocalResult = TRUE;
552         }
553         break;
554 
555     case AML_LOR_OP:                /* LOr (Integer0, Integer1) */
556 
557         if (Integer0 || Integer1)
558         {
559             LocalResult = TRUE;
560         }
561         break;
562 
563     default:
564 
565         Status = AE_AML_INTERNAL;
566         break;
567     }
568 
569     /* Return the logical result and status */
570 
571     *LogicalResult = LocalResult;
572     return_ACPI_STATUS (Status);
573 }
574 
575 
576 /*******************************************************************************
577  *
578  * FUNCTION:    AcpiExDoLogicalOp
579  *
580  * PARAMETERS:  Opcode              - AML opcode
581  *              Operand0            - operand #0
582  *              Operand1            - operand #1
583  *              LogicalResult       - TRUE/FALSE result of the operation
584  *
585  * RETURN:      Status
586  *
587  * DESCRIPTION: Execute a logical AML opcode. The purpose of having all of the
588  *              functions here is to prevent a lot of pointer dereferencing
589  *              to obtain the operands and to simplify the generation of the
590  *              logical value. For the Numeric operators (LAnd and LOr), both
591  *              operands must be integers. For the other logical operators,
592  *              operands can be any combination of Integer/String/Buffer. The
593  *              first operand determines the type to which the second operand
594  *              will be converted.
595  *
596  *              Note: cleanest machine code seems to be produced by the code
597  *              below, rather than using statements of the form:
598  *                  Result = (Operand0 == Operand1);
599  *
600  ******************************************************************************/
601 
602 ACPI_STATUS
603 AcpiExDoLogicalOp (
604     UINT16                  Opcode,
605     ACPI_OPERAND_OBJECT     *Operand0,
606     ACPI_OPERAND_OBJECT     *Operand1,
607     BOOLEAN                 *LogicalResult)
608 {
609     ACPI_OPERAND_OBJECT     *LocalOperand1 = Operand1;
610     UINT64                  Integer0;
611     UINT64                  Integer1;
612     UINT32                  Length0;
613     UINT32                  Length1;
614     ACPI_STATUS             Status = AE_OK;
615     BOOLEAN                 LocalResult = FALSE;
616     int                     Compare;
617 
618 
619     ACPI_FUNCTION_TRACE (ExDoLogicalOp);
620 
621 
622     /*
623      * Convert the second operand if necessary. The first operand
624      * determines the type of the second operand, (See the Data Types
625      * section of the ACPI 3.0+ specification.)  Both object types are
626      * guaranteed to be either Integer/String/Buffer by the operand
627      * resolution mechanism.
628      */
629     switch (Operand0->Common.Type)
630     {
631     case ACPI_TYPE_INTEGER:
632 
633         Status = AcpiExConvertToInteger (Operand1, &LocalOperand1, 16);
634         break;
635 
636     case ACPI_TYPE_STRING:
637 
638         Status = AcpiExConvertToString (Operand1, &LocalOperand1,
639                     ACPI_IMPLICIT_CONVERT_HEX);
640         break;
641 
642     case ACPI_TYPE_BUFFER:
643 
644         Status = AcpiExConvertToBuffer (Operand1, &LocalOperand1);
645         break;
646 
647     default:
648 
649         Status = AE_AML_INTERNAL;
650         break;
651     }
652 
653     if (ACPI_FAILURE (Status))
654     {
655         goto Cleanup;
656     }
657 
658     /*
659      * Two cases: 1) Both Integers, 2) Both Strings or Buffers
660      */
661     if (Operand0->Common.Type == ACPI_TYPE_INTEGER)
662     {
663         /*
664          * 1) Both operands are of type integer
665          *    Note: LocalOperand1 may have changed above
666          */
667         Integer0 = Operand0->Integer.Value;
668         Integer1 = LocalOperand1->Integer.Value;
669 
670         switch (Opcode)
671         {
672         case AML_LEQUAL_OP:             /* LEqual (Operand0, Operand1) */
673 
674             if (Integer0 == Integer1)
675             {
676                 LocalResult = TRUE;
677             }
678             break;
679 
680         case AML_LGREATER_OP:           /* LGreater (Operand0, Operand1) */
681 
682             if (Integer0 > Integer1)
683             {
684                 LocalResult = TRUE;
685             }
686             break;
687 
688         case AML_LLESS_OP:              /* LLess (Operand0, Operand1) */
689 
690             if (Integer0 < Integer1)
691             {
692                 LocalResult = TRUE;
693             }
694             break;
695 
696         default:
697 
698             Status = AE_AML_INTERNAL;
699             break;
700         }
701     }
702     else
703     {
704         /*
705          * 2) Both operands are Strings or both are Buffers
706          *    Note: Code below takes advantage of common Buffer/String
707          *          object fields. LocalOperand1 may have changed above. Use
708          *          memcmp to handle nulls in buffers.
709          */
710         Length0 = Operand0->Buffer.Length;
711         Length1 = LocalOperand1->Buffer.Length;
712 
713         /* Lexicographic compare: compare the data bytes */
714 
715         Compare = ACPI_MEMCMP (Operand0->Buffer.Pointer,
716                     LocalOperand1->Buffer.Pointer,
717                     (Length0 > Length1) ? Length1 : Length0);
718 
719         switch (Opcode)
720         {
721         case AML_LEQUAL_OP:             /* LEqual (Operand0, Operand1) */
722 
723             /* Length and all bytes must be equal */
724 
725             if ((Length0 == Length1) &&
726                 (Compare == 0))
727             {
728                 /* Length and all bytes match ==> TRUE */
729 
730                 LocalResult = TRUE;
731             }
732             break;
733 
734         case AML_LGREATER_OP:           /* LGreater (Operand0, Operand1) */
735 
736             if (Compare > 0)
737             {
738                 LocalResult = TRUE;
739                 goto Cleanup;   /* TRUE */
740             }
741             if (Compare < 0)
742             {
743                 goto Cleanup;   /* FALSE */
744             }
745 
746             /* Bytes match (to shortest length), compare lengths */
747 
748             if (Length0 > Length1)
749             {
750                 LocalResult = TRUE;
751             }
752             break;
753 
754         case AML_LLESS_OP:              /* LLess (Operand0, Operand1) */
755 
756             if (Compare > 0)
757             {
758                 goto Cleanup;   /* FALSE */
759             }
760             if (Compare < 0)
761             {
762                 LocalResult = TRUE;
763                 goto Cleanup;   /* TRUE */
764             }
765 
766             /* Bytes match (to shortest length), compare lengths */
767 
768             if (Length0 < Length1)
769             {
770                 LocalResult = TRUE;
771             }
772             break;
773 
774         default:
775 
776             Status = AE_AML_INTERNAL;
777             break;
778         }
779     }
780 
781 Cleanup:
782 
783     /* New object was created if implicit conversion performed - delete */
784 
785     if (LocalOperand1 != Operand1)
786     {
787         AcpiUtRemoveReference (LocalOperand1);
788     }
789 
790     /* Return the logical result and status */
791 
792     *LogicalResult = LocalResult;
793     return_ACPI_STATUS (Status);
794 }
795