exoparg1.c

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/******************************************************************************
 *
 * Module Name: exoparg1 - AML execution - opcodes with 1 argument
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2012, Intel Corp.
 * All rights reserved.
 *
 * 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.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * 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 MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
 */

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

#define _COMPONENT          ACPI_EXECUTER
ACPI_MODULE_NAME("exoparg1")


/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_opcode_0A_0T_1R
 *
 * PARAMETERS:  walk_state          - Current state (contains AML opcode)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Execute operator with no operands, one return value
 *
 ******************************************************************************/
acpi_status acpi_ex_opcode_0A_0T_1R(struct acpi_walk_state *walk_state)
{
    acpi_status status = AE_OK;
    union acpi_operand_object *return_desc = NULL;

    ACPI_FUNCTION_TRACE_STR(ex_opcode_0A_0T_1R,
                acpi_ps_get_opcode_name(walk_state->opcode));

    /* Examine the AML opcode */

    switch (walk_state->opcode) {
    case AML_TIMER_OP:  /*  Timer () */

        /* Create a return object of type Integer */

        return_desc =
            acpi_ut_create_integer_object(acpi_os_get_timer());
        if (!return_desc) {
            status = AE_NO_MEMORY;
            goto cleanup;
        }
        break;

    default:        /*  Unknown opcode  */

        ACPI_ERROR((AE_INFO, "Unknown AML opcode 0x%X",
                walk_state->opcode));
        status = AE_AML_BAD_OPCODE;
        break;
    }

      cleanup:

    /* Delete return object on error */

    if ((ACPI_FAILURE(status)) || walk_state->result_obj) {
        acpi_ut_remove_reference(return_desc);
        walk_state->result_obj = NULL;
    } else {
        /* Save the return value */

        walk_state->result_obj = return_desc;
    }

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_opcode_1A_0T_0R
 *
 * PARAMETERS:  walk_state          - Current state (contains AML opcode)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Execute Type 1 monadic operator with numeric operand on
 *              object stack
 *
 ******************************************************************************/

acpi_status acpi_ex_opcode_1A_0T_0R(struct acpi_walk_state *walk_state)
{
    union acpi_operand_object **operand = &walk_state->operands[0];
    acpi_status status = AE_OK;

    ACPI_FUNCTION_TRACE_STR(ex_opcode_1A_0T_0R,
                acpi_ps_get_opcode_name(walk_state->opcode));

    /* Examine the AML opcode */

    switch (walk_state->opcode) {
    case AML_RELEASE_OP:    /*  Release (mutex_object) */

        status = acpi_ex_release_mutex(operand[0], walk_state);
        break;

    case AML_RESET_OP:  /*  Reset (event_object) */

        status = acpi_ex_system_reset_event(operand[0]);
        break;

    case AML_SIGNAL_OP: /*  Signal (event_object) */

        status = acpi_ex_system_signal_event(operand[0]);
        break;

    case AML_SLEEP_OP:  /*  Sleep (msec_time) */

        status = acpi_ex_system_do_sleep(operand[0]->integer.value);
        break;

    case AML_STALL_OP:  /*  Stall (usec_time) */

        status =
            acpi_ex_system_do_stall((u32) operand[0]->integer.value);
        break;

    case AML_UNLOAD_OP: /*  Unload (Handle) */

        status = acpi_ex_unload_table(operand[0]);
        break;

    default:        /*  Unknown opcode  */

        ACPI_ERROR((AE_INFO, "Unknown AML opcode 0x%X",
                walk_state->opcode));
        status = AE_AML_BAD_OPCODE;
        break;
    }

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_opcode_1A_1T_0R
 *
 * PARAMETERS:  walk_state          - Current state (contains AML opcode)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Execute opcode with one argument, one target, and no
 *              return value.
 *
 ******************************************************************************/

acpi_status acpi_ex_opcode_1A_1T_0R(struct acpi_walk_state *walk_state)
{
    acpi_status status = AE_OK;
    union acpi_operand_object **operand = &walk_state->operands[0];

    ACPI_FUNCTION_TRACE_STR(ex_opcode_1A_1T_0R,
                acpi_ps_get_opcode_name(walk_state->opcode));

    /* Examine the AML opcode */

    switch (walk_state->opcode) {
    case AML_LOAD_OP:

        status = acpi_ex_load_op(operand[0], operand[1], walk_state);
        break;

    default:        /* Unknown opcode */

        ACPI_ERROR((AE_INFO, "Unknown AML opcode 0x%X",
                walk_state->opcode));
        status = AE_AML_BAD_OPCODE;
        goto cleanup;
    }

      cleanup:

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_opcode_1A_1T_1R
 *
 * PARAMETERS:  walk_state          - Current state (contains AML opcode)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Execute opcode with one argument, one target, and a
 *              return value.
 *
 ******************************************************************************/

acpi_status acpi_ex_opcode_1A_1T_1R(struct acpi_walk_state *walk_state)
{
    acpi_status status = AE_OK;
    union acpi_operand_object **operand = &walk_state->operands[0];
    union acpi_operand_object *return_desc = NULL;
    union acpi_operand_object *return_desc2 = NULL;
    u32 temp32;
    u32 i;
    u64 power_of_ten;
    u64 digit;

    ACPI_FUNCTION_TRACE_STR(ex_opcode_1A_1T_1R,
                acpi_ps_get_opcode_name(walk_state->opcode));

    /* Examine the AML opcode */

    switch (walk_state->opcode) {
    case AML_BIT_NOT_OP:
    case AML_FIND_SET_LEFT_BIT_OP:
    case AML_FIND_SET_RIGHT_BIT_OP:
    case AML_FROM_BCD_OP:
    case AML_TO_BCD_OP:
    case AML_COND_REF_OF_OP:

        /* Create a return object of type Integer for these opcodes */

        return_desc = acpi_ut_create_internal_object(ACPI_TYPE_INTEGER);
        if (!return_desc) {
            status = AE_NO_MEMORY;
            goto cleanup;
        }

        switch (walk_state->opcode) {
        case AML_BIT_NOT_OP:    /* Not (Operand, Result)  */

            return_desc->integer.value = ~operand[0]->integer.value;
            break;

        case AML_FIND_SET_LEFT_BIT_OP:  /* find_set_left_bit (Operand, Result) */

            return_desc->integer.value = operand[0]->integer.value;

            /*
             * Acpi specification describes Integer type as a little
             * endian unsigned value, so this boundary condition is valid.
             */
            for (temp32 = 0; return_desc->integer.value &&
                 temp32 < ACPI_INTEGER_BIT_SIZE; ++temp32) {
                return_desc->integer.value >>= 1;
            }

            return_desc->integer.value = temp32;
            break;

        case AML_FIND_SET_RIGHT_BIT_OP: /* find_set_right_bit (Operand, Result) */

            return_desc->integer.value = operand[0]->integer.value;

            /*
             * The Acpi specification describes Integer type as a little
             * endian unsigned value, so this boundary condition is valid.
             */
            for (temp32 = 0; return_desc->integer.value &&
                 temp32 < ACPI_INTEGER_BIT_SIZE; ++temp32) {
                return_desc->integer.value <<= 1;
            }

            /* Since the bit position is one-based, subtract from 33 (65) */

            return_desc->integer.value =
                temp32 ==
                0 ? 0 : (ACPI_INTEGER_BIT_SIZE + 1) - temp32;
            break;

        case AML_FROM_BCD_OP:   /* from_bcd (BCDValue, Result) */

            /*
             * The 64-bit ACPI integer can hold 16 4-bit BCD characters
             * (if table is 32-bit, integer can hold 8 BCD characters)
             * Convert each 4-bit BCD value
             */
            power_of_ten = 1;
            return_desc->integer.value = 0;
            digit = operand[0]->integer.value;

            /* Convert each BCD digit (each is one nybble wide) */

            for (i = 0;
                 (i < acpi_gbl_integer_nybble_width) && (digit > 0);
                 i++) {

                /* Get the least significant 4-bit BCD digit */

                temp32 = ((u32) digit) & 0xF;

                /* Check the range of the digit */

                if (temp32 > 9) {
                    ACPI_ERROR((AE_INFO,
                            "BCD digit too large (not decimal): 0x%X",
                            temp32));

                    status = AE_AML_NUMERIC_OVERFLOW;
                    goto cleanup;
                }

                /* Sum the digit into the result with the current power of 10 */

                return_desc->integer.value +=
                    (((u64) temp32) * power_of_ten);

                /* Shift to next BCD digit */

                digit >>= 4;

                /* Next power of 10 */

                power_of_ten *= 10;
            }
            break;

        case AML_TO_BCD_OP: /* to_bcd (Operand, Result) */

            return_desc->integer.value = 0;
            digit = operand[0]->integer.value;

            /* Each BCD digit is one nybble wide */

            for (i = 0;
                 (i < acpi_gbl_integer_nybble_width) && (digit > 0);
                 i++) {
                (void)acpi_ut_short_divide(digit, 10, &digit,
                               &temp32);

                /*
                 * Insert the BCD digit that resides in the
                 * remainder from above
                 */
                return_desc->integer.value |=
                    (((u64) temp32) << ACPI_MUL_4(i));
            }

            /* Overflow if there is any data left in Digit */

            if (digit > 0) {
                ACPI_ERROR((AE_INFO,
                        "Integer too large to convert to BCD: 0x%8.8X%8.8X",
                        ACPI_FORMAT_UINT64(operand[0]->
                                   integer.value)));
                status = AE_AML_NUMERIC_OVERFLOW;
                goto cleanup;
            }
            break;

        case AML_COND_REF_OF_OP:    /* cond_ref_of (source_object, Result) */

            /*
             * This op is a little strange because the internal return value is
             * different than the return value stored in the result descriptor
             * (There are really two return values)
             */
            if ((struct acpi_namespace_node *)operand[0] ==
                acpi_gbl_root_node) {
                /*
                 * This means that the object does not exist in the namespace,
                 * return FALSE
                 */
                return_desc->integer.value = 0;
                goto cleanup;
            }

            /* Get the object reference, store it, and remove our reference */

            status = acpi_ex_get_object_reference(operand[0],
                                  &return_desc2,
                                  walk_state);
            if (ACPI_FAILURE(status)) {
                goto cleanup;
            }

            status =
                acpi_ex_store(return_desc2, operand[1], walk_state);
            acpi_ut_remove_reference(return_desc2);

            /* The object exists in the namespace, return TRUE */

            return_desc->integer.value = ACPI_UINT64_MAX;
            goto cleanup;

        default:
            /* No other opcodes get here */
            break;
        }
        break;

    case AML_STORE_OP:  /* Store (Source, Target) */

        /*
         * A store operand is typically a number, string, buffer or lvalue
         * Be careful about deleting the source object,
         * since the object itself may have been stored.
         */
        status = acpi_ex_store(operand[0], operand[1], walk_state);
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }

        /* It is possible that the Store already produced a return object */

        if (!walk_state->result_obj) {
            /*
             * Normally, we would remove a reference on the Operand[0]
             * parameter; But since it is being used as the internal return
             * object (meaning we would normally increment it), the two
             * cancel out, and we simply don't do anything.
             */
            walk_state->result_obj = operand[0];
            walk_state->operands[0] = NULL; /* Prevent deletion */
        }
        return_ACPI_STATUS(status);

        /*
         * ACPI 2.0 Opcodes
         */
    case AML_COPY_OP:   /* Copy (Source, Target) */

        status =
            acpi_ut_copy_iobject_to_iobject(operand[0], &return_desc,
                            walk_state);
        break;

    case AML_TO_DECSTRING_OP:   /* to_decimal_string (Data, Result) */

        status = acpi_ex_convert_to_string(operand[0], &return_desc,
                           ACPI_EXPLICIT_CONVERT_DECIMAL);
        if (return_desc == operand[0]) {

            /* No conversion performed, add ref to handle return value */
            acpi_ut_add_reference(return_desc);
        }
        break;

    case AML_TO_HEXSTRING_OP:   /* to_hex_string (Data, Result) */

        status = acpi_ex_convert_to_string(operand[0], &return_desc,
                           ACPI_EXPLICIT_CONVERT_HEX);
        if (return_desc == operand[0]) {

            /* No conversion performed, add ref to handle return value */
            acpi_ut_add_reference(return_desc);
        }
        break;

    case AML_TO_BUFFER_OP:  /* to_buffer (Data, Result) */

        status = acpi_ex_convert_to_buffer(operand[0], &return_desc);
        if (return_desc == operand[0]) {

            /* No conversion performed, add ref to handle return value */
            acpi_ut_add_reference(return_desc);
        }
        break;

    case AML_TO_INTEGER_OP: /* to_integer (Data, Result) */

        status = acpi_ex_convert_to_integer(operand[0], &return_desc,
                            ACPI_ANY_BASE);
        if (return_desc == operand[0]) {

            /* No conversion performed, add ref to handle return value */
            acpi_ut_add_reference(return_desc);
        }
        break;

    case AML_SHIFT_LEFT_BIT_OP: /* shift_left_bit (Source, bit_num) */
    case AML_SHIFT_RIGHT_BIT_OP:    /* shift_right_bit (Source, bit_num) */

        /* These are two obsolete opcodes */

        ACPI_ERROR((AE_INFO,
                "%s is obsolete and not implemented",
                acpi_ps_get_opcode_name(walk_state->opcode)));
        status = AE_SUPPORT;
        goto cleanup;

    default:        /* Unknown opcode */

        ACPI_ERROR((AE_INFO, "Unknown AML opcode 0x%X",
                walk_state->opcode));
        status = AE_AML_BAD_OPCODE;
        goto cleanup;
    }

    if (ACPI_SUCCESS(status)) {

        /* Store the return value computed above into the target object */

        status = acpi_ex_store(return_desc, operand[1], walk_state);
    }

      cleanup:

    /* Delete return object on error */

    if (ACPI_FAILURE(status)) {
        acpi_ut_remove_reference(return_desc);
    }

    /* Save return object on success */

    else if (!walk_state->result_obj) {
        walk_state->result_obj = return_desc;
    }

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_opcode_1A_0T_1R
 *
 * PARAMETERS:  walk_state          - Current state (contains AML opcode)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Execute opcode with one argument, no target, and a return value
 *
 ******************************************************************************/

acpi_status acpi_ex_opcode_1A_0T_1R(struct acpi_walk_state *walk_state)
{
    union acpi_operand_object **operand = &walk_state->operands[0];
    union acpi_operand_object *temp_desc;
    union acpi_operand_object *return_desc = NULL;
    acpi_status status = AE_OK;
    u32 type;
    u64 value;

    ACPI_FUNCTION_TRACE_STR(ex_opcode_1A_0T_1R,
                acpi_ps_get_opcode_name(walk_state->opcode));

    /* Examine the AML opcode */

    switch (walk_state->opcode) {
    case AML_LNOT_OP:   /* LNot (Operand) */

        return_desc = acpi_ut_create_integer_object((u64) 0);
        if (!return_desc) {
            status = AE_NO_MEMORY;
            goto cleanup;
        }

        /*
         * Set result to ONES (TRUE) if Value == 0.  Note:
         * return_desc->Integer.Value is initially == 0 (FALSE) from above.
         */
        if (!operand[0]->integer.value) {
            return_desc->integer.value = ACPI_UINT64_MAX;
        }
        break;

    case AML_DECREMENT_OP:  /* Decrement (Operand)  */
    case AML_INCREMENT_OP:  /* Increment (Operand)  */

        /*
         * Create a new integer.  Can't just get the base integer and
         * increment it because it may be an Arg or Field.
         */
        return_desc = acpi_ut_create_internal_object(ACPI_TYPE_INTEGER);
        if (!return_desc) {
            status = AE_NO_MEMORY;
            goto cleanup;
        }

        /*
         * Since we are expecting a Reference operand, it can be either a
         * NS Node or an internal object.
         */
        temp_desc = operand[0];
        if (ACPI_GET_DESCRIPTOR_TYPE(temp_desc) ==
            ACPI_DESC_TYPE_OPERAND) {

            /* Internal reference object - prevent deletion */

            acpi_ut_add_reference(temp_desc);
        }

        /*
         * Convert the Reference operand to an Integer (This removes a
         * reference on the Operand[0] object)
         *
         * NOTE:  We use LNOT_OP here in order to force resolution of the
         * reference operand to an actual integer.
         */
        status =
            acpi_ex_resolve_operands(AML_LNOT_OP, &temp_desc,
                         walk_state);
        if (ACPI_FAILURE(status)) {
            ACPI_EXCEPTION((AE_INFO, status,
                    "While resolving operands for [%s]",
                    acpi_ps_get_opcode_name(walk_state->
                                opcode)));

            goto cleanup;
        }

        /*
         * temp_desc is now guaranteed to be an Integer object --
         * Perform the actual increment or decrement
         */
        if (walk_state->opcode == AML_INCREMENT_OP) {
            return_desc->integer.value =
                temp_desc->integer.value + 1;
        } else {
            return_desc->integer.value =
                temp_desc->integer.value - 1;
        }

        /* Finished with this Integer object */

        acpi_ut_remove_reference(temp_desc);

        /*
         * Store the result back (indirectly) through the original
         * Reference object
         */
        status = acpi_ex_store(return_desc, operand[0], walk_state);
        break;

    case AML_TYPE_OP:   /* object_type (source_object) */

        /*
         * Note: The operand is not resolved at this point because we want to
         * get the associated object, not its value.  For example, we don't
         * want to resolve a field_unit to its value, we want the actual
         * field_unit object.
         */

        /* Get the type of the base object */

        status =
            acpi_ex_resolve_multiple(walk_state, operand[0], &type,
                         NULL);
        if (ACPI_FAILURE(status)) {
            goto cleanup;
        }

        /* Allocate a descriptor to hold the type. */

        return_desc = acpi_ut_create_integer_object((u64) type);
        if (!return_desc) {
            status = AE_NO_MEMORY;
            goto cleanup;
        }
        break;

    case AML_SIZE_OF_OP:    /* size_of (source_object) */

        /*
         * Note: The operand is not resolved at this point because we want to
         * get the associated object, not its value.
         */

        /* Get the base object */

        status = acpi_ex_resolve_multiple(walk_state,
                          operand[0], &type,
                          &temp_desc);
        if (ACPI_FAILURE(status)) {
            goto cleanup;
        }

        /*
         * The type of the base object must be integer, buffer, string, or
         * package.  All others are not supported.
         *
         * NOTE: Integer is not specifically supported by the ACPI spec,
         * but is supported implicitly via implicit operand conversion.
         * rather than bother with conversion, we just use the byte width
         * global (4 or 8 bytes).
         */
        switch (type) {
        case ACPI_TYPE_INTEGER:
            value = acpi_gbl_integer_byte_width;
            break;

        case ACPI_TYPE_STRING:
            value = temp_desc->string.length;
            break;

        case ACPI_TYPE_BUFFER:

            /* Buffer arguments may not be evaluated at this point */

            status = acpi_ds_get_buffer_arguments(temp_desc);
            value = temp_desc->buffer.length;
            break;

        case ACPI_TYPE_PACKAGE:

            /* Package arguments may not be evaluated at this point */

            status = acpi_ds_get_package_arguments(temp_desc);
            value = temp_desc->package.count;
            break;

        default:
            ACPI_ERROR((AE_INFO,
                    "Operand must be Buffer/Integer/String/Package - found type %s",
                    acpi_ut_get_type_name(type)));
            status = AE_AML_OPERAND_TYPE;
            goto cleanup;
        }

        if (ACPI_FAILURE(status)) {
            goto cleanup;
        }

        /*
         * Now that we have the size of the object, create a result
         * object to hold the value
         */
        return_desc = acpi_ut_create_integer_object(value);
        if (!return_desc) {
            status = AE_NO_MEMORY;
            goto cleanup;
        }
        break;

    case AML_REF_OF_OP: /* ref_of (source_object) */

        status =
            acpi_ex_get_object_reference(operand[0], &return_desc,
                         walk_state);
        if (ACPI_FAILURE(status)) {
            goto cleanup;
        }
        break;

    case AML_DEREF_OF_OP:   /* deref_of (obj_reference | String) */

        /* Check for a method local or argument, or standalone String */

        if (ACPI_GET_DESCRIPTOR_TYPE(operand[0]) ==
            ACPI_DESC_TYPE_NAMED) {
            temp_desc =
                acpi_ns_get_attached_object((struct
                             acpi_namespace_node *)
                            operand[0]);
            if (temp_desc
                && ((temp_desc->common.type == ACPI_TYPE_STRING)
                || (temp_desc->common.type ==
                    ACPI_TYPE_LOCAL_REFERENCE))) {
                operand[0] = temp_desc;
                acpi_ut_add_reference(temp_desc);
            } else {
                status = AE_AML_OPERAND_TYPE;
                goto cleanup;
            }
        } else {
            switch ((operand[0])->common.type) {
            case ACPI_TYPE_LOCAL_REFERENCE:
                /*
                 * This is a deref_of (local_x | arg_x)
                 *
                 * Must resolve/dereference the local/arg reference first
                 */
                switch (operand[0]->reference.class) {
                case ACPI_REFCLASS_LOCAL:
                case ACPI_REFCLASS_ARG:

                    /* Set Operand[0] to the value of the local/arg */

                    status =
                        acpi_ds_method_data_get_value
                        (operand[0]->reference.class,
                         operand[0]->reference.value,
                         walk_state, &temp_desc);
                    if (ACPI_FAILURE(status)) {
                        goto cleanup;
                    }

                    /*
                     * Delete our reference to the input object and
                     * point to the object just retrieved
                     */
                    acpi_ut_remove_reference(operand[0]);
                    operand[0] = temp_desc;
                    break;

                case ACPI_REFCLASS_REFOF:

                    /* Get the object to which the reference refers */

                    temp_desc =
                        operand[0]->reference.object;
                    acpi_ut_remove_reference(operand[0]);
                    operand[0] = temp_desc;
                    break;

                default:

                    /* Must be an Index op - handled below */
                    break;
                }
                break;

            case ACPI_TYPE_STRING:
                break;

            default:
                status = AE_AML_OPERAND_TYPE;
                goto cleanup;
            }
        }

        if (ACPI_GET_DESCRIPTOR_TYPE(operand[0]) !=
            ACPI_DESC_TYPE_NAMED) {
            if ((operand[0])->common.type == ACPI_TYPE_STRING) {
                /*
                 * This is a deref_of (String). The string is a reference
                 * to a named ACPI object.
                 *
                 * 1) Find the owning Node
                 * 2) Dereference the node to an actual object. Could be a
                 *    Field, so we need to resolve the node to a value.
                 */
                status =
                    acpi_ns_get_node(walk_state->scope_info->
                             scope.node,
                             operand[0]->string.pointer,
                             ACPI_NS_SEARCH_PARENT,
                             ACPI_CAST_INDIRECT_PTR
                             (struct
                              acpi_namespace_node,
                              &return_desc));
                if (ACPI_FAILURE(status)) {
                    goto cleanup;
                }

                status =
                    acpi_ex_resolve_node_to_value
                    (ACPI_CAST_INDIRECT_PTR
                     (struct acpi_namespace_node, &return_desc),
                     walk_state);
                goto cleanup;
            }
        }

        /* Operand[0] may have changed from the code above */

        if (ACPI_GET_DESCRIPTOR_TYPE(operand[0]) ==
            ACPI_DESC_TYPE_NAMED) {
            /*
             * This is a deref_of (object_reference)
             * Get the actual object from the Node (This is the dereference).
             * This case may only happen when a local_x or arg_x is
             * dereferenced above.
             */
            return_desc = acpi_ns_get_attached_object((struct
                                   acpi_namespace_node
                                   *)
                                  operand[0]);
            acpi_ut_add_reference(return_desc);
        } else {
            /*
             * This must be a reference object produced by either the
             * Index() or ref_of() operator
             */
            switch (operand[0]->reference.class) {
            case ACPI_REFCLASS_INDEX:

                /*
                 * The target type for the Index operator must be
                 * either a Buffer or a Package
                 */
                switch (operand[0]->reference.target_type) {
                case ACPI_TYPE_BUFFER_FIELD:

                    temp_desc =
                        operand[0]->reference.object;

                    /*
                     * Create a new object that contains one element of the
                     * buffer -- the element pointed to by the index.
                     *
                     * NOTE: index into a buffer is NOT a pointer to a
                     * sub-buffer of the main buffer, it is only a pointer to a
                     * single element (byte) of the buffer!
                     *
                     * Since we are returning the value of the buffer at the
                     * indexed location, we don't need to add an additional
                     * reference to the buffer itself.
                     */
                    return_desc =
                        acpi_ut_create_integer_object((u64)
                                      temp_desc->
                                      buffer.
                                      pointer
                                      [operand
                                       [0]->
                                       reference.
                                       value]);
                    if (!return_desc) {
                        status = AE_NO_MEMORY;
                        goto cleanup;
                    }
                    break;

                case ACPI_TYPE_PACKAGE:

                    /*
                     * Return the referenced element of the package.  We must
                     * add another reference to the referenced object, however.
                     */
                    return_desc =
                        *(operand[0]->reference.where);
                    if (return_desc) {
                        acpi_ut_add_reference
                            (return_desc);
                    }
                    break;

                default:

                    ACPI_ERROR((AE_INFO,
                            "Unknown Index TargetType 0x%X in reference object %p",
                            operand[0]->reference.
                            target_type, operand[0]));
                    status = AE_AML_OPERAND_TYPE;
                    goto cleanup;
                }
                break;

            case ACPI_REFCLASS_REFOF:

                return_desc = operand[0]->reference.object;

                if (ACPI_GET_DESCRIPTOR_TYPE(return_desc) ==
                    ACPI_DESC_TYPE_NAMED) {
                    return_desc =
                        acpi_ns_get_attached_object((struct
                                     acpi_namespace_node
                                     *)
                                    return_desc);
                }

                /* Add another reference to the object! */

                acpi_ut_add_reference(return_desc);
                break;

            default:
                ACPI_ERROR((AE_INFO,
                        "Unknown class in reference(%p) - 0x%2.2X",
                        operand[0],
                        operand[0]->reference.class));

                status = AE_TYPE;
                goto cleanup;
            }
        }
        break;

    default:

        ACPI_ERROR((AE_INFO, "Unknown AML opcode 0x%X",
                walk_state->opcode));
        status = AE_AML_BAD_OPCODE;
        goto cleanup;
    }

      cleanup:

    /* Delete return object on error */

    if (ACPI_FAILURE(status)) {
        acpi_ut_remove_reference(return_desc);
    }

    /* Save return object on success */

    else {
        walk_state->result_obj = return_desc;
    }

    return_ACPI_STATUS(status);
}