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1 #ifndef CYGONCE_KERNEL_LLISTT_HXX |
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2 #define CYGONCE_KERNEL_LLISTT_HXX |
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3 |
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4 //========================================================================== |
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5 // |
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6 // llistt.hxx |
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7 // |
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8 // Llistt linked list template class declarations |
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9 // |
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10 //========================================================================== |
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11 //####COPYRIGHTBEGIN#### |
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12 // |
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13 // ------------------------------------------- |
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14 // The contents of this file are subject to the Cygnus eCos Public License |
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15 // Version 1.0 (the "License"); you may not use this file except in |
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16 // compliance with the License. You may obtain a copy of the License at |
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17 // http://sourceware.cygnus.com/ecos |
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18 // |
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19 // Software distributed under the License is distributed on an "AS IS" |
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20 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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21 // License for the specific language governing rights and limitations under |
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22 // the License. |
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23 // |
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24 // The Original Code is eCos - Embedded Cygnus Operating System, released |
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25 // September 30, 1998. |
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26 // |
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27 // The Initial Developer of the Original Code is Cygnus. Portions created |
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28 // by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved. |
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29 // ------------------------------------------- |
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30 // |
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31 //####COPYRIGHTEND#### |
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32 //========================================================================== |
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33 //#####DESCRIPTIONBEGIN#### |
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34 // |
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35 // Author(s): hmt |
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36 // Contributors: hmt |
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37 // Date: 1998-02-10 |
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38 // Purpose: Define Llistt template class |
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39 // Description: The classes defined here provide the APIs for llistts. |
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40 // Usage: #include <cyg/kernel/llistt.hxx> |
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41 // |
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42 // |
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43 //####DESCRIPTIONEND#### |
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44 // |
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45 //========================================================================== |
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46 |
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47 #include <cyg/kernel/ktypes.h> |
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48 #include <cyg/infra/cyg_ass.h> // assertion macros |
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49 #include <cyg/kernel/thread.hxx> |
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50 |
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51 // ------------------------------------------------------------------------- |
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52 // A simple linked list template; each item also contains a pointer of type |
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53 // T, and you can search for a particular T* in a list. |
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54 // |
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55 // It is intended that this list be amenable to the trick of using the |
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56 // address of the pointer that is the list head, cast to an item pointer, |
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57 // as the "zeroth" element of the list; prev of the first item is the |
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58 // address of the head pointer, and inserting before the first item works |
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59 // correctly. For this reason, a "getprev" is not provided; iteration may |
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60 // only be forwards, until a NULL is found. |
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61 // |
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62 // It is expected that derived classes will be used to hold other |
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63 // information than just the T* but that is beyond our discussion here; |
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64 // only the T* can be searched for using code provided here. |
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65 // |
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66 // This module is NOT thread-safe; it is expected that all clients will be |
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67 // seeing that that themselves. |
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68 |
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69 template <class T> |
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70 class Cyg_Llistt |
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71 { |
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72 private: |
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73 Cyg_Llistt<T> *next, *prev; |
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74 T *tptr; |
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75 |
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76 private: |
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77 // make initialisation _without_ a T* impossible. |
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78 Cyg_Llistt<T> &operator=(Cyg_Llistt<T> &); |
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79 Cyg_Llistt(Cyg_Llistt<T> &); |
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80 Cyg_Llistt(); |
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81 |
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82 public: |
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83 |
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84 CYGDBG_DEFINE_CHECK_THIS |
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85 |
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86 Cyg_Llistt( T *tvalue ) // Constructor |
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87 { |
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88 tptr = tvalue; |
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89 next = prev = NULL; |
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90 } |
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91 |
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92 ~Cyg_Llistt() // Destructor |
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93 { |
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94 CYG_ASSERT( NULL == next, "bad item next - still in list" ); |
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95 CYG_ASSERT( NULL == prev, "bad item prev - still in list" ); |
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96 } |
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97 |
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98 // iterator, basically. |
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99 Cyg_Llistt<T> * getnext() { return next; } |
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100 |
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101 // get the value |
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102 T * getitem() { return tptr; } |
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103 |
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104 // look up a particular T value in the llist |
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105 static Cyg_Llistt<T> * |
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106 find( Cyg_Llistt<T> *list, T *tvalue ) |
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107 { |
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108 for ( ; list ; list = list->next ) { |
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109 if ( list->tptr == tvalue ) |
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110 break; |
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111 } |
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112 return list; |
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113 } |
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114 |
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115 // unlink an item from the list |
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116 void |
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117 unlink() |
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118 { |
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119 CYG_ASSERT( prev, "not in a list" ); |
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120 prev->next = next; |
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121 if ( next ) { |
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122 next->prev = prev; |
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123 } |
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124 next = prev = NULL; |
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125 } |
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126 |
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127 // insert a new item in the list after "this" |
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128 void |
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129 insertafter( Cyg_Llistt<T> *item ) |
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130 { |
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131 CYG_ASSERT( item, "null item" ); |
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132 CYG_ASSERT( NULL == item->next, "bad item next - already linked" ); |
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133 CYG_ASSERT( NULL == item->prev, "bad item prev - already linked" ); |
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134 item->next = next; |
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135 item->prev = this; |
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136 if ( next ) |
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137 next->prev = item; |
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138 next = item; |
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139 } |
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140 |
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141 // insert a new item in the list before "this" |
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142 void |
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143 insertbefore( Cyg_Llistt<T> *item ) |
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144 { |
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145 CYG_ASSERT( prev, "this not in a list" ); |
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146 CYG_ASSERT( item, "null item" ); |
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147 CYG_ASSERT( NULL == item->next, "bad item next - already linked" ); |
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148 CYG_ASSERT( NULL == item->prev, "bad item prev - already linked" ); |
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149 item->prev = prev; |
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150 item->next = this; |
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151 prev->next = item; |
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152 prev = item; |
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153 } |
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154 }; |
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155 |
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156 |
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157 |
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158 // ------------------------------------------------------------------------- |
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159 #endif // ifndef CYGONCE_KERNEL_LLISTT_HXX |
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160 // EOF llistt.hxx |
