xref: /src/sys/external/bsd/acpica/dist/compiler/aslanalyze.c

/******************************************************************************
 *
 * Module Name: aslanalyze.c - Support functions for parse tree walks
 *
 *****************************************************************************/

/******************************************************************************
 *
 * 1. Copyright Notice
 *
 * Some or all of this work - Copyright (c) 1999 - 2025, Intel Corp.
 * All rights reserved.
 *
 * 2. License
 *
 * 2.1. This is your license from Intel Corp. under its intellectual property
 * rights. You may have additional license terms from the party that provided
 * you this software, covering your right to use that party's intellectual
 * property rights.
 *
 * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
 * copy of the source code appearing in this file ("Covered Code") an
 * irrevocable, perpetual, worldwide license under Intel's copyrights in the
 * base code distributed originally by Intel ("Original Intel Code") to copy,
 * make derivatives, distribute, use and display any portion of the Covered
 * Code in any form, with the right to sublicense such rights; and
 *
 * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
 * license (with the right to sublicense), under only those claims of Intel
 * patents that are infringed by the Original Intel Code, to make, use, sell,
 * offer to sell, and import the Covered Code and derivative works thereof
 * solely to the minimum extent necessary to exercise the above copyright
 * license, and in no event shall the patent license extend to any additions
 * to or modifications of the Original Intel Code. No other license or right
 * is granted directly or by implication, estoppel or otherwise;
 *
 * The above copyright and patent license is granted only if the following
 * conditions are met:
 *
 * 3. Conditions
 *
 * 3.1. Redistribution of Source with Rights to Further Distribute Source.
 * Redistribution of source code of any substantial portion of the Covered
 * Code or modification with rights to further distribute source must include
 * the above Copyright Notice, the above License, this list of Conditions,
 * and the following Disclaimer and Export Compliance provision. In addition,
 * Licensee must cause all Covered Code to which Licensee contributes to
 * contain a file documenting the changes Licensee made to create that Covered
 * Code and the date of any change. Licensee must include in that file the
 * documentation of any changes made by any predecessor Licensee. Licensee
 * must include a prominent statement that the modification is derived,
 * directly or indirectly, from Original Intel Code.
 *
 * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
 * Redistribution of source code of any substantial portion of the Covered
 * Code or modification without rights to further distribute source must
 * include the following Disclaimer and Export Compliance provision in the
 * documentation and/or other materials provided with distribution. In
 * addition, Licensee may not authorize further sublicense of source of any
 * portion of the Covered Code, and must include terms to the effect that the
 * license from Licensee to its licensee is limited to the intellectual
 * property embodied in the software Licensee provides to its licensee, and
 * not to intellectual property embodied in modifications its licensee may
 * make.
 *
 * 3.3. Redistribution of Executable. Redistribution in executable form of any
 * substantial portion of the Covered Code or modification must reproduce the
 * above Copyright Notice, and the following Disclaimer and Export Compliance
 * provision in the documentation and/or other materials provided with the
 * distribution.
 *
 * 3.4. Intel retains all right, title, and interest in and to the Original
 * Intel Code.
 *
 * 3.5. Neither the name Intel nor any other trademark owned or controlled by
 * Intel shall be used in advertising or otherwise to promote the sale, use or
 * other dealings in products derived from or relating to the Covered Code
 * without prior written authorization from Intel.
 *
 * 4. Disclaimer and Export Compliance
 *
 * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
 * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
 * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
 * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
 * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
 * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
 * PARTICULAR PURPOSE.
 *
 * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
 * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
 * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
 * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
 * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
 * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
 * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
 * LIMITED REMEDY.
 *
 * 4.3. Licensee shall not export, either directly or indirectly, any of this
 * software or system incorporating such software without first obtaining any
 * required license or other approval from the U. S. Department of Commerce or
 * any other agency or department of the United States Government. In the
 * event Licensee exports any such software from the United States or
 * re-exports any such software from a foreign destination, Licensee shall
 * ensure that the distribution and export/re-export of the software is in
 * compliance with all laws, regulations, orders, or other restrictions of the
 * U.S. Export Administration Regulations. Licensee agrees that neither it nor
 * any of its subsidiaries will export/re-export any technical data, process,
 * software, or service, directly or indirectly, to any country for which the
 * United States government or any agency thereof requires an export license,
 * other governmental approval, or letter of assurance, without first obtaining
 * such license, approval or letter.
 *
 *****************************************************************************
 *
 * Alternatively, you may choose to be licensed under the terms of the
 * following license:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, you may choose to be licensed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 *****************************************************************************/

#include "aslcompiler.h"
#include "aslcompiler.y.h"
#include "acnamesp.h"
#include <string.h>


#define _COMPONENT          ACPI_COMPILER
        ACPI_MODULE_NAME    ("aslanalyze")


/* Local Prototypes */

static ACPI_STATUS
ApDeviceSubtreeWalk (
    ACPI_PARSE_OBJECT       *Op,
    UINT32                  Level,
    void                    *Context);


/*******************************************************************************
 *
 * FUNCTION:    AnIsInternalMethod
 *
 * PARAMETERS:  Op                  - Current op
 *
 * RETURN:      Boolean
 *
 * DESCRIPTION: Check for an internal control method.
 *
 ******************************************************************************/

BOOLEAN
AnIsInternalMethod (
    ACPI_PARSE_OBJECT       *Op)
{

    if ((!strcmp (Op->Asl.ExternalName, "\\_OSI")) ||
        (!strcmp (Op->Asl.ExternalName, "_OSI")))
    {
        return (TRUE);
    }

    return (FALSE);
}


/*******************************************************************************
 *
 * FUNCTION:    AnGetInternalMethodReturnType
 *
 * PARAMETERS:  Op                  - Current op
 *
 * RETURN:      Btype
 *
 * DESCRIPTION: Get the return type of an internal method
 *
 ******************************************************************************/

UINT32
AnGetInternalMethodReturnType (
    ACPI_PARSE_OBJECT       *Op)
{

    if ((!strcmp (Op->Asl.ExternalName, "\\_OSI")) ||
        (!strcmp (Op->Asl.ExternalName, "_OSI")))
    {
        return (ACPI_BTYPE_STRING);
    }

    return (0);
}


/*******************************************************************************
 *
 * FUNCTION:    AnCheckId
 *
 * PARAMETERS:  Op                  - Current parse op
 *              Type                - HID or CID
 *
 * RETURN:      None
 *
 * DESCRIPTION: Perform various checks on _HID and _CID strings. Only limited
 *              checks can be performed on _CID strings.
 *
 ******************************************************************************/

void
AnCheckId (
    ACPI_PARSE_OBJECT       *Op,
    ACPI_NAME               Type)
{
    UINT32                  i;
    ACPI_SIZE               Length;


    /* Only care about string versions of _HID/_CID (integers are legal) */

    if (Op->Asl.ParseOpcode != PARSEOP_STRING_LITERAL)
    {
        return;
    }

    /* For both _HID and _CID, the string must be non-null */

    Length = strlen (Op->Asl.Value.String);
    if (!Length)
    {
        AslError (ASL_ERROR, ASL_MSG_NULL_STRING, Op, NULL);
        return;
    }

    /*
     * One of the things we want to catch here is the use of a leading
     * asterisk in the string -- an odd construct that certain platform
     * manufacturers are fond of. Technically, a leading asterisk is OK
     * for _CID, but a valid use of this has not been seen.
     */
    if (*Op->Asl.Value.String == '*')
    {
        AslError (ASL_ERROR, ASL_MSG_LEADING_ASTERISK,
            Op, Op->Asl.Value.String);
        return;
    }

    /* _CID strings are bus-specific, no more checks can be performed */

    if (Type == ASL_TYPE_CID)
    {
        return;
    }

    /* For _HID, all characters must be alphanumeric */

    for (i = 0; Op->Asl.Value.String[i]; i++)
    {
        if (!isalnum ((int) Op->Asl.Value.String[i]))
        {
            AslError (ASL_ERROR, ASL_MSG_ALPHANUMERIC_STRING,
                Op, Op->Asl.Value.String);
            return;
        }
    }

    /*
     * _HID String must be one of these forms:
     *
     * "AAA####"    A is an uppercase letter and # is a hex digit
     * "ACPI####"   # is a hex digit
     * "NNNN####"   N is an uppercase letter or decimal digit (0-9)
     *              # is a hex digit (ACPI 5.0)
     */
    if ((Length < 7) || (Length > 8))
    {
        AslError (ASL_ERROR, ASL_MSG_HID_LENGTH,
            Op, Op->Asl.Value.String);
        return;
    }

    /* _HID Length is valid (7 or 8), now check prefix (first 3 or 4 chars) */

    if (Length == 7)
    {
        /* AAA####: Ensure the alphabetic prefix is all uppercase */

        for (i = 0; i < 3; i++)
        {
            if (!isupper ((int) Op->Asl.Value.String[i]))
            {
                AslError (ASL_ERROR, ASL_MSG_UPPER_CASE,
                    Op, &Op->Asl.Value.String[i]);
                return;
            }
        }
    }
    else /* Length == 8 */
    {
        /*
         * ACPI#### or NNNN####:
         * Ensure the prefix contains only uppercase alpha or decimal digits
         */
        for (i = 0; i < 4; i++)
        {
            if (!isupper ((int) Op->Asl.Value.String[i]) &&
                !isdigit ((int) Op->Asl.Value.String[i]))
            {
                AslError (ASL_ERROR, ASL_MSG_HID_PREFIX,
                    Op, &Op->Asl.Value.String[i]);
                return;
            }
        }
    }

    /* Remaining characters (suffix) must be hex digits */

    for (; i < Length; i++)
    {
        if (!isxdigit ((int) Op->Asl.Value.String[i]))
        {
            AslError (ASL_ERROR, ASL_MSG_HID_SUFFIX,
                Op, &Op->Asl.Value.String[i]);
            break;
        }
    }
}


/*******************************************************************************
 *
 * FUNCTION:    AnLastStatementIsReturn
 *
 * PARAMETERS:  Op                  - A method parse node
 *
 * RETURN:      TRUE if last statement is an ASL RETURN. False otherwise
 *
 * DESCRIPTION: Walk down the list of top level statements within a method
 *              to find the last one. Check if that last statement is in
 *              fact a RETURN statement.
 *
 ******************************************************************************/

BOOLEAN
AnLastStatementIsReturn (
    ACPI_PARSE_OBJECT       *Op)
{
    ACPI_PARSE_OBJECT       *Next;


    /* Check if last statement is a return */

    Next = ASL_GET_CHILD_NODE (Op);
    while (Next)
    {
        if ((!Next->Asl.Next) &&
            (Next->Asl.ParseOpcode == PARSEOP_RETURN))
        {
            return (TRUE);
        }

        Next = ASL_GET_PEER_NODE (Next);
    }

    return (FALSE);
}


/*******************************************************************************
 *
 * FUNCTION:    AnCheckMethodReturnValue
 *
 * PARAMETERS:  Op                  - Parent
 *              OpInfo              - Parent info
 *              ArgOp               - Method invocation op
 *              RequiredBtypes      - What caller requires
 *              ThisNodeBtype       - What this node returns (if anything)
 *
 * RETURN:      None
 *
 * DESCRIPTION: Check a method invocation for 1) A return value and if it does
 *              in fact return a value, 2) check the type of the return value.
 *
 ******************************************************************************/

void
AnCheckMethodReturnValue (
    ACPI_PARSE_OBJECT       *Op,
    const ACPI_OPCODE_INFO  *OpInfo,
    ACPI_PARSE_OBJECT       *ArgOp,
    UINT32                  RequiredBtypes,
    UINT32                  ThisNodeBtype)
{
    ACPI_PARSE_OBJECT       *OwningOp;
    ACPI_NAMESPACE_NODE     *Node;
    char                    *ExternalPath;


    Node = ArgOp->Asl.Node;

    if (!Node)
    {
        /* No error message, this can happen and is OK */

        return;
    }

    /* Examine the parent op of this method */

    OwningOp = Node->Op;
    ExternalPath = AcpiNsGetNormalizedPathname (Node, TRUE);

    if (OwningOp->Asl.CompileFlags & OP_METHOD_NO_RETVAL)
    {
        /* Method NEVER returns a value */

        AslError (ASL_ERROR, ASL_MSG_NO_RETVAL, Op, ExternalPath);
    }
    else if (OwningOp->Asl.CompileFlags & OP_METHOD_SOME_NO_RETVAL)
    {
        /* Method SOMETIMES returns a value, SOMETIMES not */

        AslError (ASL_WARNING, ASL_MSG_SOME_NO_RETVAL, Op, ExternalPath);
    }
    else if (!(ThisNodeBtype & RequiredBtypes))
    {
        /* Method returns a value, but the type is wrong */

        AnFormatBtype (AslGbl_StringBuffer, ThisNodeBtype);
        AnFormatBtype (AslGbl_StringBuffer2, RequiredBtypes);

        /*
         * The case where the method does not return any value at all
         * was already handled in the namespace cross reference
         * -- Only issue an error if the method in fact returns a value,
         * but it is of the wrong type
         */
        if (ThisNodeBtype != 0)
        {
            sprintf (AslGbl_MsgBuffer,
                "Method returns [%s], %s operator requires [%s]",
                AslGbl_StringBuffer, OpInfo->Name, AslGbl_StringBuffer2);

            AslError (ASL_WARNING, ASL_MSG_INVALID_TYPE, ArgOp, AslGbl_MsgBuffer);
        }
    }

    if (ExternalPath)
    {
        ACPI_FREE (ExternalPath);
    }
}


/*******************************************************************************
 *
 * FUNCTION:    AnIsResultUsed
 *
 * PARAMETERS:  Op                  - Parent op for the operator
 *
 * RETURN:      TRUE if result from this operation is actually consumed
 *
 * DESCRIPTION: Determine if the function result value from an operator is
 *              used.
 *
 ******************************************************************************/

BOOLEAN
AnIsResultUsed (
    ACPI_PARSE_OBJECT       *Op)
{
    ACPI_PARSE_OBJECT       *Parent;


    switch (Op->Asl.ParseOpcode)
    {
    case PARSEOP_INCREMENT:
    case PARSEOP_DECREMENT:

        /* These are standalone operators, no return value */

        return (TRUE);

    default:

        break;
    }

    /* Examine parent to determine if the return value is used */

    Parent = Op->Asl.Parent;
    switch (Parent->Asl.ParseOpcode)
    {
    /* If/While - check if the operator is the predicate */

    case PARSEOP_IF:
    case PARSEOP_WHILE:

        /* First child is the predicate */

        if (Parent->Asl.Child == Op)
        {
            return (TRUE);
        }

        return (FALSE);

    /* Not used if one of these is the parent */

    case PARSEOP_METHOD:
    case PARSEOP_DEFINITION_BLOCK:
    case PARSEOP_ELSE:

        return (FALSE);

    default:

        /* Any other type of parent means that the result is used */

        return (TRUE);
    }
}


/*******************************************************************************
 *
 * FUNCTION:    ApCheckForGpeNameConflict
 *
 * PARAMETERS:  Op                  - Current parse op
 *
 * RETURN:      None
 *
 * DESCRIPTION: Check for a conflict between GPE names within this scope.
 *              Conflict means two GPE names with the same GPE number, but
 *              different types -- such as _L1C and _E1C.
 *
 ******************************************************************************/

void
ApCheckForGpeNameConflict (
    ACPI_PARSE_OBJECT       *Op)
{
    ACPI_PARSE_OBJECT       *NextOp;
    UINT32                  GpeNumber;
    char                    Name[ACPI_NAMESEG_SIZE + 1];
    char                    Target[ACPI_NAMESEG_SIZE] ACPI_NONSTRING;


    /**
     * Need a null-terminated string version of NameSeg
     *
     * NOTE: during a review on Name[ACPI_NAMESEG_SIZE + 1] having an extra
     *       byte[1], compiler testing exhibited a difference in behavior between
     *       GCC and Clang[2] (at least; MSVC may also exhibit the same) in
     *       how optimization is done. The extra byte is needed to ensure
     *       the signature does not get mangled, subsequently avoiding
     *       GpeNumber being a completely different return value from strtoul.
     *
     *       [1] https://github.com/acpica/acpica/pull/1019#discussion_r2058687704
     *       [2] https://github.com/acpica/acpica/pull/1019#discussion_r2061953039
     */

    ACPI_MOVE_32_TO_32 (Name, Op->Asl.NameSeg);
    Name[ACPI_NAMESEG_SIZE] = 0;

    /*
     * For a GPE method:
     * 1st char must be underscore
     * 2nd char must be L or E
     * 3rd/4th chars must be a hex number
     */
    if ((Name[0] != '_') ||
       ((Name[1] != 'L') && (Name[1] != 'E')))
    {
        return;
    }

    /* Verify 3rd/4th chars are a valid hex value */

    GpeNumber = strtoul (&Name[2], NULL, 16);
    if (GpeNumber == ACPI_UINT32_MAX)
    {
        return;
    }

    /*
     * We are now sure we have an _Lxx or _Exx.
     * Create the target name that would cause collision (Flip E/L)
     */
    ACPI_MOVE_32_TO_32 (Target, Name);

    /* Inject opposite letter ("L" versus "E") */

    if (Name[1] == 'L')
    {
        Target[1] = 'E';
    }
    else /* Name[1] == 'E' */
    {
        Target[1] = 'L';
    }

    /* Search all peers (objects within this scope) for target match */

    NextOp = Op->Asl.Next;
    while (NextOp)
    {
        /*
         * We mostly care about methods, but check Name() constructs also,
         * even though they will get another error for not being a method.
         * All GPE names must be defined as control methods.
         */
        if ((NextOp->Asl.ParseOpcode == PARSEOP_METHOD) ||
            (NextOp->Asl.ParseOpcode == PARSEOP_NAME))
        {
            if (ACPI_COMPARE_NAMESEG (Target, NextOp->Asl.NameSeg))
            {
                /* Found both _Exy and _Lxy in the same scope, error */

                AslError (ASL_ERROR, ASL_MSG_GPE_NAME_CONFLICT, NextOp,
                    Name);
                return;
            }
        }

        NextOp = NextOp->Asl.Next;
    }

    /* OK, no conflict found */

    return;
}


/*******************************************************************************
 *
 * FUNCTION:    ApCheckRegMethod
 *
 * PARAMETERS:  Op                  - Current parse op
 *
 * RETURN:      None
 *
 * DESCRIPTION: Ensure that a _REG method has a corresponding Operation
 *              Region declaration within the same scope. Note: _REG is defined
 *              to have two arguments and must therefore be defined as a
 *              control method.
 *
 ******************************************************************************/

void
ApCheckRegMethod (
    ACPI_PARSE_OBJECT       *Op)
{
    ACPI_PARSE_OBJECT       *Next;
    ACPI_PARSE_OBJECT       *Parent;


    /* We are only interested in _REG methods */

    if (!ACPI_COMPARE_NAMESEG (METHOD_NAME__REG, &Op->Asl.NameSeg))
    {
        return;
    }

    /* Get the start of the current scope */

    Parent = Op->Asl.Parent;
    Next = Parent->Asl.Child;

    /* Search entire scope for an operation region declaration */

    while (Next)
    {
        if (Next->Asl.ParseOpcode == PARSEOP_OPERATIONREGION)
        {
            return; /* Found region, OK */
        }

        Next = Next->Asl.Next;
    }

    /* No region found, issue warning */

    AslError (ASL_WARNING, ASL_MSG_NO_REGION, Op, NULL);
}


/*******************************************************************************
 *
 * FUNCTION:    ApFindNameInDeviceTree
 *
 * PARAMETERS:  Name                - Name to search for
 *              Op                  - Current parse op
 *
 * RETURN:      TRUE if name found in the same scope as Op.
 *
 * DESCRIPTION: Determine if a name appears in the same scope as Op, as either
 *              a Method() or a Name(). "Same scope" can mean under an If or
 *              Else statement.
 *
 * NOTE: Detects _HID/_ADR in this type of construct (legal in ACPI 6.1+)
 *
 * Scope (\_SB.PCI0)
 * {
 *     Device (I2C0)
 *     {
 *         If (SMD0 != 4) {
 *             Name (_HID, "INT3442")
 *         } Else {
 *             Name (_ADR, 0x400)
 *         }
 *     }
 * }
 ******************************************************************************/

BOOLEAN
ApFindNameInDeviceTree (
    char                    *Name,
    ACPI_PARSE_OBJECT       *Op)
{
    ACPI_STATUS             Status;


    Status = TrWalkParseTree (Op, ASL_WALK_VISIT_DOWNWARD,
        ApDeviceSubtreeWalk, NULL, Name);

    if (Status == AE_CTRL_TRUE)
    {
        return (TRUE);  /* Found a match */
    }

    return (FALSE);
}


/* Callback function for interface above */

static ACPI_STATUS
ApDeviceSubtreeWalk (
    ACPI_PARSE_OBJECT       *Op,
    UINT32                  Level,
    void                    *Context)
{
    char                    *Name = ACPI_CAST_PTR (char, Context);


    switch (Op->Asl.ParseOpcode)
    {
    case PARSEOP_DEVICE:

        /* Level 0 is the starting device, ignore it */

        if (Level > 0)
        {
            /* Ignore sub-devices */

            return (AE_CTRL_DEPTH);
        }
        break;

    case PARSEOP_NAME:
    case PARSEOP_METHOD:

        /* These are what we are looking for */

        if (ACPI_COMPARE_NAMESEG (Name, Op->Asl.NameSeg))
        {
            return (AE_CTRL_TRUE);
        }
        return (AE_CTRL_DEPTH);

    case PARSEOP_SCOPE:
    case PARSEOP_FIELD:
    case PARSEOP_OPERATIONREGION:

        /*
         * We want to ignore these, because either they can be large
         * subtrees or open a scope to somewhere else.
         */
        return (AE_CTRL_DEPTH);

    default:
        break;
    }

    return (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    ApFindNameInScope
 *
 * PARAMETERS:  Name                - Name to search for
 *              Op                  - Current parse op
 *
 * RETURN:      TRUE if name found in the same scope as Op.
 *
 * DESCRIPTION: Determine if a name appears in the same scope as Op, as either
 *              a Method() or a Name().
 *
 ******************************************************************************/

BOOLEAN
ApFindNameInScope (
    char                    *Name,
    ACPI_PARSE_OBJECT       *Op)
{
    ACPI_PARSE_OBJECT       *Next;
    ACPI_PARSE_OBJECT       *Parent;


    /* Get the start of the current scope */

    Parent = Op->Asl.Parent;
    Next = Parent->Asl.Child;

    /* Search entire scope for a match to the name */

    while (Next)
    {
        if ((Next->Asl.ParseOpcode == PARSEOP_METHOD) ||
            (Next->Asl.ParseOpcode == PARSEOP_NAME))
        {
            if (ACPI_COMPARE_NAMESEG (Name, Next->Asl.NameSeg))
            {
                return (TRUE);
            }
        }

        Next = Next->Asl.Next;
    }

    return (FALSE);
}