drivers/acpi/parser/pswalk.c

   1 /******************************************************************************
   2  *
   3  * Module Name: pswalk - Parser routines to walk parsed op tree(s)
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2006, R. Byron Moore
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <acpi/acpi.h>
  45 #include <acpi/acparser.h>
  46
  47 #define _COMPONENT          ACPI_PARSER
  48 ACPI_MODULE_NAME("pswalk")
  49
  50 /*******************************************************************************
  51  *
  52  * FUNCTION:    acpi_ps_delete_parse_tree
  53  *
  54  * PARAMETERS:  subtree_root        - Root of tree (or subtree) to delete
  55  *
  56  * RETURN:      None
  57  *
  58  * DESCRIPTION: Delete a portion of or an entire parse tree.
  59  *
  60  ******************************************************************************/
  61 void acpi_ps_delete_parse_tree(union acpi_parse_object *subtree_root)
  62 {
  63         union acpi_parse_object *op = subtree_root;
  64         union acpi_parse_object *next = NULL;
  65         union acpi_parse_object *parent = NULL;
  66
  67         ACPI_FUNCTION_TRACE_PTR("ps_delete_parse_tree", subtree_root);
  68
  69         /* Visit all nodes in the subtree */
  70
  71         while (op) {
  72
  73                 /* Check if we are not ascending */
  74
  75                 if (op != parent) {
  76
  77                         /* Look for an argument or child of the current op */
  78
  79                         next = acpi_ps_get_arg(op, 0);
  80                         if (next) {
  81
  82                                 /* Still going downward in tree (Op is not completed yet) */
  83
  84                                 op = next;
  85                                 continue;
  86                         }
  87                 }
  88
  89                 /* No more children, this Op is complete. */
  90
  91                 next = op->common.next;
  92                 parent = op->common.parent;
  93
  94                 acpi_ps_free_op(op);
  95
  96                 /* If we are back to the starting point, the walk is complete. */
  97
  98                 if (op == subtree_root) {
  99                         return_VOID;
 100                 }
 101                 if (next) {
 102                         op = next;
 103                 } else {
 104                         op = parent;
 105                 }
 106         }
 107
 108         return_VOID;
 109 }