acpica/dispatcher/dsfield.c

/******************************************************************************
 *
 * Module Name: dsfield - Dispatcher field routines
 *
 *****************************************************************************/

/******************************************************************************
 *
 * 1. Copyright Notice
 *
 * Some or all of this work - Copyright (c) 1999 - 2009, 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.
 *
 *****************************************************************************/

#define __DSFIELD_C__

#include "acpi.h"
#include "accommon.h"
#include "amlcode.h"
#include "acdispat.h"
#include "acinterp.h"
#include "acnamesp.h"
#include "acparser.h"


#define _COMPONENT          ACPI_DISPATCHER
        ACPI_MODULE_NAME    ("dsfield")

/* Local prototypes */

static ACPI_STATUS
AcpiDsGetFieldNames (
    ACPI_CREATE_FIELD_INFO  *Info,
    ACPI_WALK_STATE         *WalkState,
    ACPI_PARSE_OBJECT       *Arg);


/*******************************************************************************
 *
 * FUNCTION:    AcpiDsCreateBufferField
 *
 * PARAMETERS:  Op                  - Current parse op (CreateXXField)
 *              WalkState           - Current state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Execute the CreateField operators:
 *              CreateBitFieldOp,
 *              CreateByteFieldOp,
 *              CreateWordFieldOp,
 *              CreateDWordFieldOp,
 *              CreateQWordFieldOp,
 *              CreateFieldOp       (all of which define a field in a buffer)
 *
 ******************************************************************************/

ACPI_STATUS
AcpiDsCreateBufferField (
    ACPI_PARSE_OBJECT       *Op,
    ACPI_WALK_STATE         *WalkState)
{
    ACPI_PARSE_OBJECT       *Arg;
    ACPI_NAMESPACE_NODE     *Node;
    ACPI_STATUS             Status;
    ACPI_OPERAND_OBJECT     *ObjDesc;
    ACPI_OPERAND_OBJECT     *SecondDesc = NULL;
    UINT32                  Flags;


    ACPI_FUNCTION_TRACE (DsCreateBufferField);


    /*
     * Get the NameString argument (name of the new BufferField)
     */
    if (Op->Common.AmlOpcode == AML_CREATE_FIELD_OP)
    {
        /* For CreateField, name is the 4th argument */

        Arg = AcpiPsGetArg (Op, 3);
    }
    else
    {
        /* For all other CreateXXXField operators, name is the 3rd argument */

        Arg = AcpiPsGetArg (Op, 2);
    }

    if (!Arg)
    {
        return_ACPI_STATUS (AE_AML_NO_OPERAND);
    }

    if (WalkState->DeferredNode)
    {
        Node = WalkState->DeferredNode;
        Status = AE_OK;
    }
    else
    {
        /* Execute flag should always be set when this function is entered */

        if (!(WalkState->ParseFlags & ACPI_PARSE_EXECUTE))
        {
            return_ACPI_STATUS (AE_AML_INTERNAL);
        }

        /* Creating new namespace node, should not already exist */

        Flags = ACPI_NS_NO_UPSEARCH | ACPI_NS_DONT_OPEN_SCOPE |
                ACPI_NS_ERROR_IF_FOUND;

        /*
         * Mark node temporary if we are executing a normal control
         * method. (Don't mark if this is a module-level code method)
         */
        if (WalkState->MethodNode &&
            !(WalkState->ParseFlags & ACPI_PARSE_MODULE_LEVEL))
        {
            Flags |= ACPI_NS_TEMPORARY;
        }

        /* Enter the NameString into the namespace */

        Status = AcpiNsLookup (WalkState->ScopeInfo, Arg->Common.Value.String,
                    ACPI_TYPE_ANY, ACPI_IMODE_LOAD_PASS1,
                    Flags, WalkState, &Node);
        if (ACPI_FAILURE (Status))
        {
            ACPI_ERROR_NAMESPACE (Arg->Common.Value.String, Status);
            return_ACPI_STATUS (Status);
        }
    }

    /*
     * We could put the returned object (Node) on the object stack for later,
     * but for now, we will put it in the "op" object that the parser uses,
     * so we can get it again at the end of this scope.
     */
    Op->Common.Node = Node;

    /*
     * If there is no object attached to the node, this node was just created
     * and we need to create the field object. Otherwise, this was a lookup
     * of an existing node and we don't want to create the field object again.
     */
    ObjDesc = AcpiNsGetAttachedObject (Node);
    if (ObjDesc)
    {
        return_ACPI_STATUS (AE_OK);
    }

    /*
     * The Field definition is not fully parsed at this time.
     * (We must save the address of the AML for the buffer and index operands)
     */

    /* Create the buffer field object */

    ObjDesc = AcpiUtCreateInternalObject (ACPI_TYPE_BUFFER_FIELD);
    if (!ObjDesc)
    {
        Status = AE_NO_MEMORY;
        goto Cleanup;
    }

    /*
     * Remember location in AML stream of the field unit opcode and operands --
     * since the buffer and index operands must be evaluated.
     */
    SecondDesc                  = ObjDesc->Common.NextObject;
    SecondDesc->Extra.AmlStart  = Op->Named.Data;
    SecondDesc->Extra.AmlLength = Op->Named.Length;
    ObjDesc->BufferField.Node   = Node;

    /* Attach constructed field descriptors to parent node */

    Status = AcpiNsAttachObject (Node, ObjDesc, ACPI_TYPE_BUFFER_FIELD);
    if (ACPI_FAILURE (Status))
    {
        goto Cleanup;
    }


Cleanup:

    /* Remove local reference to the object */

    AcpiUtRemoveReference (ObjDesc);
    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiDsGetFieldNames
 *
 * PARAMETERS:  Info            - CreateField info structure
 *  `           WalkState       - Current method state
 *              Arg             - First parser arg for the field name list
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Process all named fields in a field declaration.  Names are
 *              entered into the namespace.
 *
 ******************************************************************************/

static ACPI_STATUS
AcpiDsGetFieldNames (
    ACPI_CREATE_FIELD_INFO  *Info,
    ACPI_WALK_STATE         *WalkState,
    ACPI_PARSE_OBJECT       *Arg)
{
    ACPI_STATUS             Status;
    ACPI_INTEGER            Position;


    ACPI_FUNCTION_TRACE_PTR (DsGetFieldNames, Info);


    /* First field starts at bit zero */

    Info->FieldBitPosition = 0;

    /* Process all elements in the field list (of parse nodes) */

    while (Arg)
    {
        /*
         * Three types of field elements are handled:
         * 1) Offset - specifies a bit offset
         * 2) AccessAs - changes the access mode
         * 3) Name - Enters a new named field into the namespace
         */
        switch (Arg->Common.AmlOpcode)
        {
        case AML_INT_RESERVEDFIELD_OP:

            Position = (ACPI_INTEGER) Info->FieldBitPosition
                        + (ACPI_INTEGER) Arg->Common.Value.Size;

            if (Position > ACPI_UINT32_MAX)
            {
                ACPI_ERROR ((AE_INFO,
                    "Bit offset within field too large (> 0xFFFFFFFF)"));
                return_ACPI_STATUS (AE_SUPPORT);
            }

            Info->FieldBitPosition = (UINT32) Position;
            break;


        case AML_INT_ACCESSFIELD_OP:

            /*
             * Get a new AccessType and AccessAttribute -- to be used for all
             * field units that follow, until field end or another AccessAs
             * keyword.
             *
             * In FieldFlags, preserve the flag bits other than the
             * ACCESS_TYPE bits
             */
            Info->FieldFlags = (UINT8)
                ((Info->FieldFlags & ~(AML_FIELD_ACCESS_TYPE_MASK)) |
                ((UINT8) ((UINT32) Arg->Common.Value.Integer >> 8)));

            Info->Attribute = (UINT8) (Arg->Common.Value.Integer);
            break;


        case AML_INT_NAMEDFIELD_OP:

            /* Lookup the name, it should already exist */

            Status = AcpiNsLookup (WalkState->ScopeInfo,
                        (char *) &Arg->Named.Name, Info->FieldType,
                        ACPI_IMODE_EXECUTE, ACPI_NS_DONT_OPEN_SCOPE,
                        WalkState, &Info->FieldNode);
            if (ACPI_FAILURE (Status))
            {
                ACPI_ERROR_NAMESPACE ((char *) &Arg->Named.Name, Status);
                return_ACPI_STATUS (Status);
            }
            else
            {
                Arg->Common.Node = Info->FieldNode;
                Info->FieldBitLength = Arg->Common.Value.Size;

                /*
                 * If there is no object attached to the node, this node was
                 * just created and we need to create the field object.
                 * Otherwise, this was a lookup of an existing node and we
                 * don't want to create the field object again.
                 */
                if (!AcpiNsGetAttachedObject (Info->FieldNode))
                {
                    Status = AcpiExPrepFieldValue (Info);
                    if (ACPI_FAILURE (Status))
                    {
                        return_ACPI_STATUS (Status);
                    }
                }
            }

            /* Keep track of bit position for the next field */

            Position = (ACPI_INTEGER) Info->FieldBitPosition
                        + (ACPI_INTEGER) Arg->Common.Value.Size;

            if (Position > ACPI_UINT32_MAX)
            {
                ACPI_ERROR ((AE_INFO,
                    "Field [%4.4s] bit offset too large (> 0xFFFFFFFF)",
                    ACPI_CAST_PTR (char, &Info->FieldNode->Name)));
                return_ACPI_STATUS (AE_SUPPORT);
            }

            Info->FieldBitPosition += Info->FieldBitLength;
            break;


        default:

            ACPI_ERROR ((AE_INFO,
                "Invalid opcode in field list: %X", Arg->Common.AmlOpcode));
            return_ACPI_STATUS (AE_AML_BAD_OPCODE);
        }

        Arg = Arg->Common.Next;
    }

    return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiDsCreateField
 *
 * PARAMETERS:  Op              - Op containing the Field definition and args
 *              RegionNode      - Object for the containing Operation Region
 *  `           WalkState       - Current method state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Create a new field in the specified operation region
 *
 ******************************************************************************/

ACPI_STATUS
AcpiDsCreateField (
    ACPI_PARSE_OBJECT       *Op,
    ACPI_NAMESPACE_NODE     *RegionNode,
    ACPI_WALK_STATE         *WalkState)
{
    ACPI_STATUS             Status;
    ACPI_PARSE_OBJECT       *Arg;
    ACPI_CREATE_FIELD_INFO  Info;


    ACPI_FUNCTION_TRACE_PTR (DsCreateField, Op);


    /* First arg is the name of the parent OpRegion (must already exist) */

    Arg = Op->Common.Value.Arg;
    if (!RegionNode)
    {
        Status = AcpiNsLookup (WalkState->ScopeInfo, Arg->Common.Value.Name,
                        ACPI_TYPE_REGION, ACPI_IMODE_EXECUTE,
                        ACPI_NS_SEARCH_PARENT, WalkState, &RegionNode);
        if (ACPI_FAILURE (Status))
        {
            ACPI_ERROR_NAMESPACE (Arg->Common.Value.Name, Status);
            return_ACPI_STATUS (Status);
        }
    }

    /* Second arg is the field flags */

    Arg = Arg->Common.Next;
    Info.FieldFlags = (UINT8) Arg->Common.Value.Integer;
    Info.Attribute = 0;

    /* Each remaining arg is a Named Field */

    Info.FieldType = ACPI_TYPE_LOCAL_REGION_FIELD;
    Info.RegionNode = RegionNode;

    Status = AcpiDsGetFieldNames (&Info, WalkState, Arg->Common.Next);

    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiDsInitFieldObjects
 *
 * PARAMETERS:  Op              - Op containing the Field definition and args
 *  `           WalkState       - Current method state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: For each "Field Unit" name in the argument list that is
 *              part of the field declaration, enter the name into the
 *              namespace.
 *
 ******************************************************************************/

ACPI_STATUS
AcpiDsInitFieldObjects (
    ACPI_PARSE_OBJECT       *Op,
    ACPI_WALK_STATE         *WalkState)
{
    ACPI_STATUS             Status;
    ACPI_PARSE_OBJECT       *Arg = NULL;
    ACPI_NAMESPACE_NODE     *Node;
    UINT8                   Type = 0;
    UINT32                  Flags;


    ACPI_FUNCTION_TRACE_PTR (DsInitFieldObjects, Op);


    /* Execute flag should always be set when this function is entered */

    if (!(WalkState->ParseFlags & ACPI_PARSE_EXECUTE))
    {
        if (WalkState->ParseFlags & ACPI_PARSE_DEFERRED_OP)
        {
            /* BankField Op is deferred, just return OK */

            return_ACPI_STATUS (AE_OK);
        }

        return_ACPI_STATUS (AE_AML_INTERNAL);
    }

    /*
     * Get the FieldList argument for this opcode. This is the start of the
     * list of field elements.
     */
    switch (WalkState->Opcode)
    {
    case AML_FIELD_OP:
        Arg = AcpiPsGetArg (Op, 2);
        Type = ACPI_TYPE_LOCAL_REGION_FIELD;
        break;

    case AML_BANK_FIELD_OP:
        Arg = AcpiPsGetArg (Op, 4);
        Type = ACPI_TYPE_LOCAL_BANK_FIELD;
        break;

    case AML_INDEX_FIELD_OP:
        Arg = AcpiPsGetArg (Op, 3);
        Type = ACPI_TYPE_LOCAL_INDEX_FIELD;
        break;

    default:
        return_ACPI_STATUS (AE_BAD_PARAMETER);
    }

    /* Creating new namespace node(s), should not already exist */

    Flags = ACPI_NS_NO_UPSEARCH | ACPI_NS_DONT_OPEN_SCOPE |
            ACPI_NS_ERROR_IF_FOUND;

    /*
     * Mark node(s) temporary if we are executing a normal control
     * method. (Don't mark if this is a module-level code method)
     */
    if (WalkState->MethodNode &&
        !(WalkState->ParseFlags & ACPI_PARSE_MODULE_LEVEL))
    {
        Flags |= ACPI_NS_TEMPORARY;
    }

    /*
     * Walk the list of entries in the FieldList
     * Note: FieldList can be of zero length. In this case, Arg will be NULL.
     */
    while (Arg)
    {
        /*
         * Ignore OFFSET and ACCESSAS terms here; we are only interested in the
         * field names in order to enter them into the namespace.
         */
        if (Arg->Common.AmlOpcode == AML_INT_NAMEDFIELD_OP)
        {
            Status = AcpiNsLookup (WalkState->ScopeInfo,
                        (char *) &Arg->Named.Name, Type, ACPI_IMODE_LOAD_PASS1,
                        Flags, WalkState, &Node);
            if (ACPI_FAILURE (Status))
            {
                ACPI_ERROR_NAMESPACE ((char *) &Arg->Named.Name, Status);
                if (Status != AE_ALREADY_EXISTS)
                {
                    return_ACPI_STATUS (Status);
                }

                /* Name already exists, just ignore this error */

                Status = AE_OK;
            }

            Arg->Common.Node = Node;
        }

        /* Get the next field element in the list */

        Arg = Arg->Common.Next;
    }

    return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiDsCreateBankField
 *
 * PARAMETERS:  Op              - Op containing the Field definition and args
 *              RegionNode      - Object for the containing Operation Region
 *              WalkState       - Current method state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Create a new bank field in the specified operation region
 *
 ******************************************************************************/

ACPI_STATUS
AcpiDsCreateBankField (
    ACPI_PARSE_OBJECT       *Op,
    ACPI_NAMESPACE_NODE     *RegionNode,
    ACPI_WALK_STATE         *WalkState)
{
    ACPI_STATUS             Status;
    ACPI_PARSE_OBJECT       *Arg;
    ACPI_CREATE_FIELD_INFO  Info;


    ACPI_FUNCTION_TRACE_PTR (DsCreateBankField, Op);


    /* First arg is the name of the parent OpRegion (must already exist) */

    Arg = Op->Common.Value.Arg;
    if (!RegionNode)
    {
        Status = AcpiNsLookup (WalkState->ScopeInfo, Arg->Common.Value.Name,
                        ACPI_TYPE_REGION, ACPI_IMODE_EXECUTE,
                        ACPI_NS_SEARCH_PARENT, WalkState, &RegionNode);
        if (ACPI_FAILURE (Status))
        {
            ACPI_ERROR_NAMESPACE (Arg->Common.Value.Name, Status);
            return_ACPI_STATUS (Status);
        }
    }

    /* Second arg is the Bank Register (Field) (must already exist) */

    Arg = Arg->Common.Next;
    Status = AcpiNsLookup (WalkState->ScopeInfo, Arg->Common.Value.String,
                    ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,
                    ACPI_NS_SEARCH_PARENT, WalkState, &Info.RegisterNode);
    if (ACPI_FAILURE (Status))
    {
        ACPI_ERROR_NAMESPACE (Arg->Common.Value.String, Status);
        return_ACPI_STATUS (Status);
    }

    /*
     * Third arg is the BankValue
     * This arg is a TermArg, not a constant
     * It will be evaluated later, by AcpiDsEvalBankFieldOperands
     */
    Arg = Arg->Common.Next;

    /* Fourth arg is the field flags */

    Arg = Arg->Common.Next;
    Info.FieldFlags = (UINT8) Arg->Common.Value.Integer;

    /* Each remaining arg is a Named Field */

    Info.FieldType = ACPI_TYPE_LOCAL_BANK_FIELD;
    Info.RegionNode = RegionNode;

    /*
     * Use Info.DataRegisterNode to store BankField Op
     * It's safe because DataRegisterNode will never be used when create bank field
     * We store AmlStart and AmlLength in the BankField Op for late evaluation
     * Used in AcpiExPrepFieldValue(Info)
     *
     * TBD: Or, should we add a field in ACPI_CREATE_FIELD_INFO, like "void *ParentOp"?
     */
    Info.DataRegisterNode = (ACPI_NAMESPACE_NODE*) Op;

    Status = AcpiDsGetFieldNames (&Info, WalkState, Arg->Common.Next);
    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiDsCreateIndexField
 *
 * PARAMETERS:  Op              - Op containing the Field definition and args
 *              RegionNode      - Object for the containing Operation Region
 *  `           WalkState       - Current method state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Create a new index field in the specified operation region
 *
 ******************************************************************************/

ACPI_STATUS
AcpiDsCreateIndexField (
    ACPI_PARSE_OBJECT       *Op,
    ACPI_NAMESPACE_NODE     *RegionNode,
    ACPI_WALK_STATE         *WalkState)
{
    ACPI_STATUS             Status;
    ACPI_PARSE_OBJECT       *Arg;
    ACPI_CREATE_FIELD_INFO  Info;


    ACPI_FUNCTION_TRACE_PTR (DsCreateIndexField, Op);


    /* First arg is the name of the Index register (must already exist) */

    Arg = Op->Common.Value.Arg;
    Status = AcpiNsLookup (WalkState->ScopeInfo, Arg->Common.Value.String,
                    ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,
                    ACPI_NS_SEARCH_PARENT, WalkState, &Info.RegisterNode);
    if (ACPI_FAILURE (Status))
    {
        ACPI_ERROR_NAMESPACE (Arg->Common.Value.String, Status);
        return_ACPI_STATUS (Status);
    }

    /* Second arg is the data register (must already exist) */

    Arg = Arg->Common.Next;
    Status = AcpiNsLookup (WalkState->ScopeInfo, Arg->Common.Value.String,
                    ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,
                    ACPI_NS_SEARCH_PARENT, WalkState, &Info.DataRegisterNode);
    if (ACPI_FAILURE (Status))
    {
        ACPI_ERROR_NAMESPACE (Arg->Common.Value.String, Status);
        return_ACPI_STATUS (Status);
    }

    /* Next arg is the field flags */

    Arg = Arg->Common.Next;
    Info.FieldFlags = (UINT8) Arg->Common.Value.Integer;

    /* Each remaining arg is a Named Field */

    Info.FieldType = ACPI_TYPE_LOCAL_INDEX_FIELD;
    Info.RegionNode = RegionNode;

    Status = AcpiDsGetFieldNames (&Info, WalkState, Arg->Common.Next);

    return_ACPI_STATUS (Status);
}