// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
 *
 * Module Name: dscontrol - Support for execution control opcodes -
 *                          if/else/while/return
 *
 * Copyright (C) 2000 - 2025, Intel Corp.
 *
 *****************************************************************************/

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

#define _COMPONENT          ACPI_DISPATCHER
ACPI_MODULE_NAME("dscontrol")

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_exec_begin_control_op
 *
 * PARAMETERS:  walk_list       - The list that owns the walk stack
 *              op              - The control Op
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Handles all control ops encountered during control method
 *              execution.
 *
 ******************************************************************************/
acpi_status
acpi_ds_exec_begin_control_op(struct acpi_walk_state *walk_state,
                              union acpi_parse_object *op)
{
        acpi_status status = AE_OK;
        union acpi_generic_state *control_state;

        ACPI_FUNCTION_NAME(ds_exec_begin_control_op);

        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "Op=%p Opcode=%2.2X State=%p\n",
                          op, op->common.aml_opcode, walk_state));

        switch (op->common.aml_opcode) {
        case AML_WHILE_OP:
                /*
                 * If this is an additional iteration of a while loop, continue.
                 * There is no need to allocate a new control state.
                 */
                if (walk_state->control_state) {
                        if (walk_state->control_state->control.
                            aml_predicate_start ==
                            (walk_state->parser_state.aml - 1)) {

                                /* Reset the state to start-of-loop */

                                walk_state->control_state->common.state =
                                    ACPI_CONTROL_CONDITIONAL_EXECUTING;
                                break;
                        }
                }

                ACPI_FALLTHROUGH;

        case AML_IF_OP:
                /*
                 * IF/WHILE: Create a new control state to manage these
                 * constructs. We need to manage these as a stack, in order
                 * to handle nesting.
                 */
                control_state = acpi_ut_create_control_state();
                if (!control_state) {
                        status = AE_NO_MEMORY;
                        break;
                }
                /*
                 * Save a pointer to the predicate for multiple executions
                 * of a loop
                 */
                control_state->control.aml_predicate_start =
                    walk_state->parser_state.aml - 1;
                control_state->control.package_end =
                    walk_state->parser_state.pkg_end;
                control_state->control.opcode = op->common.aml_opcode;
                control_state->control.loop_timeout = acpi_os_get_timer() +
                    ((u64)acpi_gbl_max_loop_iterations * ACPI_100NSEC_PER_SEC);

                /* Push the control state on this walk's control stack */

                acpi_ut_push_generic_state(&walk_state->control_state,
                                           control_state);
                break;

        case AML_ELSE_OP:

                /* Predicate is in the state object */
                /* If predicate is true, the IF was executed, ignore ELSE part */

                if (walk_state->last_predicate) {
                        status = AE_CTRL_TRUE;
                }

                break;

        case AML_RETURN_OP:

                break;

        default:

                break;
        }

        return (status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_exec_end_control_op
 *
 * PARAMETERS:  walk_list       - The list that owns the walk stack
 *              op              - The control Op
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Handles all control ops encountered during control method
 *              execution.
 *
 ******************************************************************************/

acpi_status
acpi_ds_exec_end_control_op(struct acpi_walk_state *walk_state,
                            union acpi_parse_object *op)
{
        acpi_status status = AE_OK;
        union acpi_generic_state *control_state;

        ACPI_FUNCTION_NAME(ds_exec_end_control_op);

        switch (op->common.aml_opcode) {
        case AML_IF_OP:

                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[IF_OP] Op=%p\n", op));

                /*
                 * Save the result of the predicate in case there is an
                 * ELSE to come
                 */
                walk_state->last_predicate =
                    (u8)walk_state->control_state->common.value;

                /*
                 * Pop the control state that was created at the start
                 * of the IF and free it
                 */
                control_state =
                    acpi_ut_pop_generic_state(&walk_state->control_state);
                acpi_ut_delete_generic_state(control_state);
                break;

        case AML_ELSE_OP:

                break;

        case AML_WHILE_OP:

                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[WHILE_OP] Op=%p\n", op));

                control_state = walk_state->control_state;
                if (control_state->common.value) {

                        /* Predicate was true, the body of the loop was just executed */

                        /*
                         * This infinite loop detection mechanism allows the interpreter
                         * to escape possibly infinite loops. This can occur in poorly
                         * written AML when the hardware does not respond within a while
                         * loop and the loop does not implement a timeout.
                         */
                        if (ACPI_TIME_AFTER(acpi_os_get_timer(),
                                            control_state->control.
                                            loop_timeout)) {
                                status = AE_AML_LOOP_TIMEOUT;
                                break;
                        }

                        /*
                         * Go back and evaluate the predicate and maybe execute the loop
                         * another time
                         */
                        status = AE_CTRL_PENDING;
                        walk_state->aml_last_while =
                            control_state->control.aml_predicate_start;
                        break;
                }

                /* Predicate was false, terminate this while loop */

                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                                  "[WHILE_OP] termination! Op=%p\n", op));

                /* Pop this control state and free it */

                control_state =
                    acpi_ut_pop_generic_state(&walk_state->control_state);
                acpi_ut_delete_generic_state(control_state);
                break;

        case AML_RETURN_OP:

                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                                  "[RETURN_OP] Op=%p Arg=%p\n", op,
                                  op->common.value.arg));

                /*
                 * One optional operand -- the return value
                 * It can be either an immediate operand or a result that
                 * has been bubbled up the tree
                 */
                if (op->common.value.arg) {

                        /* Since we have a real Return(), delete any implicit return */

                        acpi_ds_clear_implicit_return(walk_state);

                        /* Return statement has an immediate operand */

                        status =
                            acpi_ds_create_operands(walk_state,
                                                    op->common.value.arg);
                        if (ACPI_FAILURE(status)) {
                                return (status);
                        }

                        /*
                         * If value being returned is a Reference (such as
                         * an arg or local), resolve it now because it may
                         * cease to exist at the end of the method.
                         */
                        status =
                            acpi_ex_resolve_to_value(&walk_state->operands[0],
                                                     walk_state);
                        if (ACPI_FAILURE(status)) {
                                return (status);
                        }

                        /*
                         * Get the return value and save as the last result
                         * value. This is the only place where walk_state->return_desc
                         * is set to anything other than zero!
                         */
                        walk_state->return_desc = walk_state->operands[0];
                } else if (walk_state->result_count) {

                        /* Since we have a real Return(), delete any implicit return */

                        acpi_ds_clear_implicit_return(walk_state);

                        /*
                         * The return value has come from a previous calculation.
                         *
                         * If value being returned is a Reference (such as
                         * an arg or local), resolve it now because it may
                         * cease to exist at the end of the method.
                         *
                         * Allow references created by the Index operator to return
                         * unchanged.
                         */
                        if ((ACPI_GET_DESCRIPTOR_TYPE
                             (walk_state->results->results.obj_desc[0]) ==
                             ACPI_DESC_TYPE_OPERAND)
                            && ((walk_state->results->results.obj_desc[0])->
                                common.type == ACPI_TYPE_LOCAL_REFERENCE)
                            && ((walk_state->results->results.obj_desc[0])->
                                reference.class != ACPI_REFCLASS_INDEX)) {
                                status =
                                    acpi_ex_resolve_to_value(&walk_state->
                                                             results->results.
                                                             obj_desc[0],
                                                             walk_state);
                                if (ACPI_FAILURE(status)) {
                                        return (status);
                                }
                        }

                        walk_state->return_desc =
                            walk_state->results->results.obj_desc[0];
                } else {
                        /* No return operand */

                        if (walk_state->num_operands) {
                                acpi_ut_remove_reference(walk_state->
                                                         operands[0]);
                        }

                        walk_state->operands[0] = NULL;
                        walk_state->num_operands = 0;
                        walk_state->return_desc = NULL;
                }

                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                                  "Completed RETURN_OP State=%p, RetVal=%p\n",
                                  walk_state, walk_state->return_desc));

                /* End the control method execution right now */

                status = AE_CTRL_TERMINATE;
                break;

        case AML_NOOP_OP:

                /* Just do nothing! */

                break;

        case AML_BREAKPOINT_OP:

                acpi_db_signal_break_point(walk_state);

                /* Call to the OSL in case OS wants a piece of the action */

                status = acpi_os_signal(ACPI_SIGNAL_BREAKPOINT,
                                        "Executed AML Breakpoint opcode");
                break;

        case AML_BREAK_OP:
        case AML_CONTINUE_OP:   /* ACPI 2.0 */

                /* Pop and delete control states until we find a while */

                while (walk_state->control_state &&
                       (walk_state->control_state->control.opcode !=
                        AML_WHILE_OP)) {
                        control_state =
                            acpi_ut_pop_generic_state(&walk_state->
                                                      control_state);
                        acpi_ut_delete_generic_state(control_state);
                }

                /* No while found? */

                if (!walk_state->control_state) {
                        return (AE_AML_NO_WHILE);
                }

                /* Was: walk_state->aml_last_while = walk_state->control_state->Control.aml_predicate_start; */

                walk_state->aml_last_while =
                    walk_state->control_state->control.package_end;

                /* Return status depending on opcode */

                if (op->common.aml_opcode == AML_BREAK_OP) {
                        status = AE_CTRL_BREAK;
                } else {
                        status = AE_CTRL_CONTINUE;
                }
                break;

        default:

                ACPI_ERROR((AE_INFO, "Unknown control opcode=0x%X Op=%p",
                            op->common.aml_opcode, op));

                status = AE_AML_BAD_OPCODE;
                break;
        }

        return (status);
}