1 | /* SPDX-License-Identifier: BSD-2-Clause */ |
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2 | |
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3 | /** |
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4 | * @file |
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5 | * |
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6 | * @ingroup RTEMSScoreChain |
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7 | * |
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8 | * @brief This header file provides interfaces of the |
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9 | * @ref RTEMSScoreChain which are used by the implementation and the API. |
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10 | */ |
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11 | |
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12 | /* |
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13 | * Copyright (c) 2010 embedded brains GmbH. |
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14 | * |
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15 | * COPYRIGHT (c) 1989-2006. |
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16 | * On-Line Applications Research Corporation (OAR). |
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17 | * |
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18 | * Redistribution and use in source and binary forms, with or without |
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19 | * modification, are permitted provided that the following conditions |
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20 | * are met: |
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21 | * 1. Redistributions of source code must retain the above copyright |
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22 | * notice, this list of conditions and the following disclaimer. |
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23 | * 2. Redistributions in binary form must reproduce the above copyright |
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24 | * notice, this list of conditions and the following disclaimer in the |
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25 | * documentation and/or other materials provided with the distribution. |
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26 | * |
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27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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28 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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29 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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30 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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31 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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32 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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33 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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34 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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35 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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36 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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37 | * POSSIBILITY OF SUCH DAMAGE. |
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38 | */ |
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39 | |
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40 | #ifndef _RTEMS_SCORE_CHAIN_H |
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41 | #define _RTEMS_SCORE_CHAIN_H |
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42 | |
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43 | #ifdef __cplusplus |
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44 | extern "C" { |
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45 | #endif |
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46 | |
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47 | /** |
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48 | * @defgroup RTEMSScoreChain Chain Handler |
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49 | * |
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50 | * @ingroup RTEMSScore |
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51 | * |
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52 | * @brief This group contains the Chain Handler implementation. |
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53 | * |
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54 | * The Chain Handler is used to manage sets of entities. This handler |
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55 | * provides two data structures. The Chain Node data structure is included |
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56 | * as the first part of every data structure that will be placed on |
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57 | * a chain. The second data structure is Chain Control which is used |
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58 | * to manage a set of Chain Nodes. |
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59 | * |
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60 | * @{ |
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61 | */ |
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62 | |
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63 | /** |
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64 | * @brief This structure represents a chain node. |
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65 | * |
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66 | * This is used to manage each element (node) which is placed |
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67 | * on a chain. |
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68 | * |
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69 | * @note Typically, a more complicated structure will use the |
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70 | * chain package. The more complicated structure will |
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71 | * include a chain node as the first element in its |
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72 | * control structure. It will then call the chain package |
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73 | * with a pointer to that node element. The node pointer |
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74 | * and the higher level structure start at the same address |
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75 | * so the user can cast the pointers back and forth. |
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76 | * |
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77 | */ |
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78 | typedef struct Chain_Node { |
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79 | /** This points to the node after this one on this chain. */ |
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80 | struct Chain_Node *next; |
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81 | /** This points to the node immediate prior to this one on this chain. */ |
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82 | struct Chain_Node *previous; |
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83 | } Chain_Node; |
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84 | |
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85 | /** |
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86 | * @brief This union represents a chain control block. |
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87 | * |
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88 | * This is used to manage a chain. A chain consists of a doubly |
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89 | * linked list of zero or more nodes. |
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90 | * |
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91 | * @note This implementation does not require special checks for |
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92 | * manipulating the first and last elements on the chain. |
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93 | * To accomplish this the @a Chain_Control structure is |
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94 | * treated as two overlapping @ref Chain_Node structures. |
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95 | */ |
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96 | typedef union { |
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97 | struct { |
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98 | Chain_Node Node; |
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99 | Chain_Node *fill; |
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100 | } Head; |
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101 | |
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102 | struct { |
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103 | Chain_Node *fill; |
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104 | Chain_Node Node; |
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105 | } Tail; |
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106 | } Chain_Control; |
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107 | |
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108 | /** @} */ |
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109 | |
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110 | #ifdef __cplusplus |
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111 | } |
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112 | #endif |
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113 | |
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114 | #endif |
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115 | /* end of include file */ |
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