drivers/acpi/executer/exoparg1.c

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

/*
 * Copyright (C) 2000 - 2005, R. Byron Moore
 * 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 <acpi/acparser.h>
#include <acpi/acdispat.h>
#include <acpi/acinterp.h>
#include <acpi/amlcode.h>
#include <acpi/acnamesp.h>


#define _COMPONENT          ACPI_EXECUTER
	 ACPI_MODULE_NAME    ("exoparg1")


/*!
 * Naming convention for AML interpreter execution routines.
 *
 * The routines that begin execution of AML opcodes are named with a common
 * convention based upon the number of arguments, the number of target operands,
 * and whether or not a value is returned:
 *
 *      AcpiExOpcode_xA_yT_zR
 *
 * Where:
 *
 * xA - ARGUMENTS:    The number of arguments (input operands) that are
 *                    required for this opcode type (0 through 6 args).
 * yT - TARGETS:      The number of targets (output operands) that are required
 *                    for this opcode type (0, 1, or 2 targets).
 * zR - RETURN VALUE: Indicates whether this opcode type returns a value
 *                    as the function return (0 or 1).
 *
 * The AcpiExOpcode* functions are called via the Dispatcher component with
 * fully resolved operands.
!*/

/*******************************************************************************
 *
 * 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_internal_object (ACPI_TYPE_INTEGER);
		if (!return_desc) {
			status = AE_NO_MEMORY;
			goto cleanup;
		}

		return_desc->integer.value = acpi_os_get_timer ();
		break;

	default:                /*  Unknown opcode  */

		ACPI_REPORT_ERROR (("acpi_ex_opcode_0A_0T_1R: Unknown opcode %X\n",
			walk_state->opcode));
		status = AE_AML_BAD_OPCODE;
		break;
	}

cleanup:

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

	/* Delete return object on error */

	if (ACPI_FAILURE (status)) {
		acpi_ut_remove_reference (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_suspend (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_REPORT_ERROR (("acpi_ex_opcode_1A_0T_0R: Unknown opcode %X\n",
			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_REPORT_ERROR (("acpi_ex_opcode_1A_1T_0R: Unknown opcode %X\n",
			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;
	acpi_integer                    power_of_ten;
	acpi_integer                    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_DEBUG_PRINT ((ACPI_DB_ERROR,
						"BCD digit too large (not decimal): 0x%X\n",
						temp32));

					status = AE_AML_NUMERIC_OVERFLOW;
					goto cleanup;
				}

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

				return_desc->integer.value += (((acpi_integer) 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 |= (((acpi_integer) temp32) <<
						   ACPI_MUL_4 (i));
			}

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

			if (digit > 0) {
				ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
					"Integer too large to convert to BCD: %8.8X%8.8X\n",
					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_INTEGER_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_DEBUG_PRINT ((ACPI_DB_ERROR,
			"%s is obsolete and not implemented\n",
			acpi_ps_get_opcode_name (walk_state->opcode)));
		status = AE_SUPPORT;
		goto cleanup;


	default:                        /* Unknown opcode */

		ACPI_REPORT_ERROR (("acpi_ex_opcode_1A_1T_1R: Unknown opcode %X\n",
			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:

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

	/* Delete return object on error */

	if (ACPI_FAILURE (status)) {
		acpi_ut_remove_reference (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;
	acpi_integer                    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_internal_object (ACPI_TYPE_INTEGER);
		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_INTEGER_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_DEBUG_PRINT ((ACPI_DB_ERROR, "%s: bad operand(s) %s\n",
				acpi_ps_get_opcode_name (walk_state->opcode),
				acpi_format_exception(status)));

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

		return_desc->integer.value = type;
		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_BUFFER:
			value = temp_desc->buffer.length;
			break;

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

		case ACPI_TYPE_PACKAGE:
			value = temp_desc->package.count;
			break;

		default:
			ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
				"size_of - Operand is not Buf/Int/Str/Pkg - found type %s\n",
				acpi_ut_get_type_name (type)));
			status = AE_AML_OPERAND_TYPE;
			goto cleanup;
		}

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

		return_desc->integer.value = value;
		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) {
			switch (ACPI_GET_OBJECT_TYPE (operand[0])) {
			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.opcode) {
				case AML_LOCAL_OP:
				case AML_ARG_OP:

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

					status = acpi_ds_method_data_get_value (operand[0]->reference.opcode,
							 operand[0]->reference.offset, 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 AML_REF_OF_OP:

					/* 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:

				/*
				 * 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 nee
				 *    to resolve the node to a value.
				 */
				status = acpi_ns_get_node_by_path (operand[0]->string.pointer,
						  walk_state->scope_info->scope.node, 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;


			default:

				status = AE_AML_OPERAND_TYPE;
				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]);
		}
		else {
			/*
			 * This must be a reference object produced by either the Index() or
			 * ref_of() operator
			 */
			switch (operand[0]->reference.opcode) {
			case AML_INDEX_OP:

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

					/*
					 * 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->integer.value =
						temp_desc->buffer.pointer[operand[0]->reference.offset];
					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) {
						/*
						 * We can't return a NULL dereferenced value.  This is
						 * an uninitialized package element and is thus a
						 * severe error.
						 */
						ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
							"NULL package element obj %p\n",
							operand[0]));
						status = AE_AML_UNINITIALIZED_ELEMENT;
						goto cleanup;
					}

					acpi_ut_add_reference (return_desc);
					break;


				default:

					ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
						"Unknown Index target_type %X in obj %p\n",
						operand[0]->reference.target_type, operand[0]));
					status = AE_AML_OPERAND_TYPE;
					goto cleanup;
				}
				break;


			case AML_REF_OF_OP:

				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_DEBUG_PRINT ((ACPI_DB_ERROR,
					"Unknown opcode in ref(%p) - %X\n",
					operand[0], operand[0]->reference.opcode));

				status = AE_TYPE;
				goto cleanup;
			}
		}
		break;


	default:

		ACPI_REPORT_ERROR (("acpi_ex_opcode_1A_0T_1R: Unknown opcode %X\n",
			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);
	}

	walk_state->result_obj = return_desc;
	return_ACPI_STATUS (status);
}