1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup ScoreChain |
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5 | * |
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6 | * @brief Chain Handler API |
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7 | */ |
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8 | |
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9 | /* |
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10 | * Copyright (c) 2010 embedded brains GmbH. |
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11 | * |
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12 | * COPYRIGHT (c) 1989-2006. |
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13 | * On-Line Applications Research Corporation (OAR). |
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14 | * |
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15 | * The license and distribution terms for this file may be |
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16 | * found in the file LICENSE in this distribution or at |
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17 | * http://www.rtems.org/license/LICENSE. |
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18 | */ |
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19 | |
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20 | #ifndef _RTEMS_SCORE_CHAIN_H |
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21 | #define _RTEMS_SCORE_CHAIN_H |
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22 | |
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23 | #ifdef __cplusplus |
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24 | extern "C" { |
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25 | #endif |
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26 | |
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27 | /** |
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28 | * @defgroup ScoreChain Chain Handler |
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29 | * |
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30 | * @ingroup Score |
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31 | * |
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32 | * The Chain Handler is used to manage sets of entities. This handler |
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33 | * provides two data structures. The Chain Node data structure is included |
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34 | * as the first part of every data structure that will be placed on |
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35 | * a chain. The second data structure is Chain Control which is used |
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36 | * to manage a set of Chain Nodes. |
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37 | */ |
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38 | /**@{*/ |
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39 | |
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40 | /** |
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41 | * @typedef Chain_Node |
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42 | * |
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43 | * This type definition promotes the name for the Chain Node used by |
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44 | * all RTEMS code. It is a separate type definition because a forward |
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45 | * reference is required to define it. See @ref Chain_Node_struct for |
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46 | * detailed information. |
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47 | */ |
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48 | typedef struct Chain_Node_struct Chain_Node; |
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49 | |
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50 | /** |
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51 | * @struct Chain_Node_struct |
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52 | * |
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53 | * This is used to manage each element (node) which is placed |
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54 | * on a chain. |
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55 | * |
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56 | * @note Typically, a more complicated structure will use the |
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57 | * chain package. The more complicated structure will |
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58 | * include a chain node as the first element in its |
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59 | * control structure. It will then call the chain package |
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60 | * with a pointer to that node element. The node pointer |
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61 | * and the higher level structure start at the same address |
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62 | * so the user can cast the pointers back and forth. |
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63 | * |
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64 | */ |
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65 | struct Chain_Node_struct { |
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66 | /** This points to the node after this one on this chain. */ |
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67 | Chain_Node *next; |
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68 | /** This points to the node immediate prior to this one on this chain. */ |
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69 | Chain_Node *previous; |
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70 | }; |
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71 | |
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72 | /** |
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73 | * @struct Chain_Control |
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74 | * |
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75 | * This is used to manage a chain. A chain consists of a doubly |
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76 | * linked list of zero or more nodes. |
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77 | * |
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78 | * @note This implementation does not require special checks for |
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79 | * manipulating the first and last elements on the chain. |
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80 | * To accomplish this the @a Chain_Control structure is |
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81 | * treated as two overlapping @ref Chain_Node structures. |
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82 | */ |
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83 | typedef union { |
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84 | struct { |
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85 | Chain_Node Node; |
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86 | Chain_Node *fill; |
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87 | } Head; |
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88 | |
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89 | struct { |
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90 | Chain_Node *fill; |
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91 | Chain_Node Node; |
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92 | } Tail; |
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93 | } Chain_Control; |
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94 | |
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95 | /**@}*/ |
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96 | |
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97 | #ifdef __cplusplus |
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98 | } |
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99 | #endif |
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100 | |
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101 | #endif |
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102 | /* end of include file */ |
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