1 | /* |
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2 | * Semaphore Manager |
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3 | * |
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4 | * DESCRIPTION: |
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5 | * |
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6 | * This package is the implementation of the Semaphore Manager. |
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7 | * This manager utilizes standard Dijkstra counting semaphores to provide |
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8 | * synchronization and mutual exclusion capabilities. |
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9 | * |
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10 | * Directives provided are: |
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11 | * |
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12 | * + create a semaphore |
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13 | * + get an ID of a semaphore |
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14 | * + delete a semaphore |
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15 | * + acquire a semaphore |
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16 | * + release a semaphore |
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17 | * |
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18 | * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. |
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19 | * On-Line Applications Research Corporation (OAR). |
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20 | * All rights assigned to U.S. Government, 1994. |
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21 | * |
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22 | * This material may be reproduced by or for the U.S. Government pursuant |
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23 | * to the copyright license under the clause at DFARS 252.227-7013. This |
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24 | * notice must appear in all copies of this file and its derivatives. |
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25 | * |
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26 | * $Id$ |
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27 | */ |
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28 | |
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29 | #include <rtems/system.h> |
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30 | #include <rtems/support.h> |
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31 | #include <rtems/attr.h> |
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32 | #include <rtems/config.h> |
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33 | #include <rtems/isr.h> |
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34 | #include <rtems/object.h> |
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35 | #include <rtems/options.h> |
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36 | #include <rtems/sem.h> |
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37 | #include <rtems/states.h> |
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38 | #include <rtems/thread.h> |
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39 | #include <rtems/threadq.h> |
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40 | #include <rtems/mpci.h> |
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41 | |
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42 | /*PAGE |
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43 | * |
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44 | * _Semaphore_Manager_initialization |
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45 | * |
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46 | * This routine initializes all semaphore manager related data structures. |
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47 | * |
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48 | * Input parameters: |
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49 | * maximum_semaphores - maximum configured semaphores |
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50 | * |
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51 | * Output parameters: NONE |
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52 | */ |
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53 | |
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54 | void _Semaphore_Manager_initialization( |
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55 | unsigned32 maximum_semaphores |
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56 | ) |
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57 | { |
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58 | _Objects_Initialize_information( |
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59 | &_Semaphore_Information, |
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60 | OBJECTS_RTEMS_SEMAPHORES, |
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61 | TRUE, |
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62 | maximum_semaphores, |
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63 | sizeof( Semaphore_Control ), |
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64 | FALSE, |
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65 | RTEMS_MAXIMUM_NAME_LENGTH, |
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66 | FALSE |
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67 | ); |
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68 | } |
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69 | |
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70 | /*PAGE |
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71 | * |
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72 | * rtems_semaphore_create |
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73 | * |
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74 | * This directive creates a semaphore and sets the initial value based |
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75 | * on the given count. A semaphore id is returned. |
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76 | * |
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77 | * Input parameters: |
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78 | * name - user defined semaphore name |
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79 | * count - initial count of semaphore |
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80 | * attribute_set - semaphore attributes |
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81 | * id - pointer to semaphore id |
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82 | * |
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83 | * Output parameters: |
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84 | * id - semaphore id |
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85 | * RTEMS_SUCCESSFUL - if successful |
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86 | * error code - if unsuccessful |
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87 | */ |
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88 | |
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89 | rtems_status_code rtems_semaphore_create( |
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90 | rtems_name name, |
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91 | unsigned32 count, |
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92 | rtems_attribute attribute_set, |
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93 | Objects_Id *id |
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94 | ) |
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95 | { |
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96 | register Semaphore_Control *the_semaphore; |
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97 | |
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98 | if ( !rtems_is_name_valid( name ) ) |
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99 | return ( RTEMS_INVALID_NAME ); |
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100 | |
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101 | if ( _Attributes_Is_global( attribute_set ) ) { |
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102 | |
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103 | if ( !_Configuration_Is_multiprocessing() ) |
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104 | return( RTEMS_MP_NOT_CONFIGURED ); |
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105 | |
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106 | if ( _Attributes_Is_inherit_priority( attribute_set ) ) |
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107 | return( RTEMS_NOT_DEFINED ); |
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108 | |
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109 | } else if ( _Attributes_Is_inherit_priority( attribute_set ) ) { |
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110 | |
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111 | if ( ! ( _Attributes_Is_binary_semaphore( attribute_set ) && |
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112 | _Attributes_Is_priority( attribute_set ) ) ) |
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113 | return( RTEMS_NOT_DEFINED ); |
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114 | |
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115 | } |
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116 | |
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117 | if ( _Attributes_Is_binary_semaphore( attribute_set ) && ( count > 1 ) ) |
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118 | return( RTEMS_INVALID_NUMBER ); |
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119 | |
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120 | _Thread_Disable_dispatch(); /* prevents deletion */ |
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121 | |
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122 | the_semaphore = _Semaphore_Allocate(); |
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123 | |
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124 | if ( !the_semaphore ) { |
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125 | _Thread_Enable_dispatch(); |
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126 | return( RTEMS_TOO_MANY ); |
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127 | } |
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128 | |
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129 | if ( _Attributes_Is_global( attribute_set ) && |
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130 | !( _Objects_MP_Open( &_Semaphore_Information, name, |
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131 | the_semaphore->Object.id, FALSE ) ) ) { |
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132 | _Semaphore_Free( the_semaphore ); |
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133 | _Thread_Enable_dispatch(); |
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134 | return( RTEMS_TOO_MANY ); |
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135 | } |
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136 | |
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137 | the_semaphore->attribute_set = attribute_set; |
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138 | the_semaphore->count = count; |
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139 | |
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140 | if ( _Attributes_Is_binary_semaphore( attribute_set ) && count == 0 ) { |
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141 | the_semaphore->nest_count = 1; |
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142 | the_semaphore->holder = _Thread_Executing; |
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143 | the_semaphore->holder_id = _Thread_Executing->Object.id; |
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144 | _Thread_Executing->resource_count++; |
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145 | } else { |
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146 | the_semaphore->nest_count = 0; |
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147 | the_semaphore->holder = NULL; |
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148 | the_semaphore->holder_id = 0; |
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149 | } |
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150 | |
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151 | _Thread_queue_Initialize( &the_semaphore->Wait_queue, |
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152 | attribute_set, STATES_WAITING_FOR_SEMAPHORE ); |
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153 | |
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154 | _Objects_Open( &_Semaphore_Information, &the_semaphore->Object, &name ); |
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155 | |
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156 | *id = the_semaphore->Object.id; |
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157 | |
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158 | if ( _Attributes_Is_global( attribute_set ) ) |
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159 | _Semaphore_MP_Send_process_packet( |
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160 | SEMAPHORE_MP_ANNOUNCE_CREATE, |
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161 | the_semaphore->Object.id, |
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162 | name, |
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163 | 0 /* Not used */ |
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164 | ); |
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165 | _Thread_Enable_dispatch(); |
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166 | return( RTEMS_SUCCESSFUL ); |
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167 | } |
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168 | |
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169 | /*PAGE |
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170 | * |
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171 | * rtems_semaphore_ident |
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172 | * |
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173 | * This directive returns the system ID associated with |
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174 | * the semaphore name. |
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175 | * |
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176 | * Input parameters: |
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177 | * name - user defined semaphore name |
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178 | * node - node(s) to be searched |
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179 | * id - pointer to semaphore id |
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180 | * |
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181 | * Output parameters: |
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182 | * *id - semaphore id |
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183 | * RTEMS_SUCCESSFUL - if successful |
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184 | * error code - if unsuccessful |
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185 | */ |
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186 | |
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187 | rtems_status_code rtems_semaphore_ident( |
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188 | rtems_name name, |
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189 | unsigned32 node, |
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190 | Objects_Id *id |
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191 | ) |
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192 | { |
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193 | return( _Objects_Name_to_id( &_Semaphore_Information, &name, node, id ) ); |
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194 | } |
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195 | |
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196 | /*PAGE |
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197 | * |
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198 | * rtems_semaphore_delete |
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199 | * |
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200 | * This directive allows a thread to delete a semaphore specified by |
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201 | * the semaphore id. The semaphore is freed back to the inactive |
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202 | * semaphore chain. |
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203 | * |
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204 | * Input parameters: |
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205 | * id - semaphore id |
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206 | * |
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207 | * Output parameters: |
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208 | * RTEMS_SUCCESSFUL - if successful |
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209 | * error code - if unsuccessful |
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210 | */ |
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211 | |
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212 | rtems_status_code rtems_semaphore_delete( |
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213 | Objects_Id id |
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214 | ) |
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215 | { |
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216 | register Semaphore_Control *the_semaphore; |
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217 | Objects_Locations location; |
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218 | |
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219 | the_semaphore = _Semaphore_Get( id, &location ); |
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220 | switch ( location ) { |
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221 | case OBJECTS_ERROR: |
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222 | return( RTEMS_INVALID_ID ); |
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223 | case OBJECTS_REMOTE: |
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224 | _Thread_Dispatch(); |
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225 | return( RTEMS_ILLEGAL_ON_REMOTE_OBJECT ); |
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226 | case OBJECTS_LOCAL: |
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227 | if ( _Attributes_Is_binary_semaphore( the_semaphore->attribute_set) && |
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228 | ( the_semaphore->count == 0 ) ) { |
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229 | _Thread_Enable_dispatch(); |
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230 | return( RTEMS_RESOURCE_IN_USE ); |
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231 | } |
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232 | |
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233 | _Objects_Close( &_Semaphore_Information, &the_semaphore->Object ); |
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234 | |
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235 | _Thread_queue_Flush( |
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236 | &the_semaphore->Wait_queue, |
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237 | _Semaphore_MP_Send_object_was_deleted |
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238 | ); |
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239 | |
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240 | _Semaphore_Free( the_semaphore ); |
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241 | |
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242 | if ( _Attributes_Is_global( the_semaphore->attribute_set ) ) { |
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243 | |
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244 | _Objects_MP_Close( &_Semaphore_Information, the_semaphore->Object.id ); |
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245 | |
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246 | _Semaphore_MP_Send_process_packet( |
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247 | SEMAPHORE_MP_ANNOUNCE_DELETE, |
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248 | the_semaphore->Object.id, |
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249 | 0, /* Not used */ |
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250 | 0 /* Not used */ |
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251 | ); |
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252 | } |
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253 | _Thread_Enable_dispatch(); |
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254 | return( RTEMS_SUCCESSFUL ); |
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255 | } |
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256 | |
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257 | return( RTEMS_INTERNAL_ERROR ); /* unreached - only to remove warnings */ |
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258 | } |
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259 | |
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260 | /*PAGE |
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261 | * |
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262 | * rtems_semaphore_obtain |
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263 | * |
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264 | * This directive allows a thread to acquire a semaphore. |
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265 | * |
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266 | * Input parameters: |
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267 | * id - semaphore id |
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268 | * option_set - wait option |
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269 | * timeout - number of ticks to wait (0 means wait forever) |
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270 | * |
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271 | * Output parameters: |
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272 | * RTEMS_SUCCESSFUL - if successful |
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273 | * error code - if unsuccessful |
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274 | */ |
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275 | |
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276 | rtems_status_code rtems_semaphore_obtain( |
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277 | Objects_Id id, |
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278 | unsigned32 option_set, |
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279 | rtems_interval timeout |
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280 | ) |
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281 | { |
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282 | register Semaphore_Control *the_semaphore; |
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283 | Objects_Locations location; |
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284 | |
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285 | the_semaphore = _Semaphore_Get( id, &location ); |
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286 | switch ( location ) { |
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287 | case OBJECTS_ERROR: |
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288 | return( RTEMS_INVALID_ID ); |
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289 | case OBJECTS_REMOTE: |
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290 | return _Semaphore_MP_Send_request_packet( |
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291 | SEMAPHORE_MP_OBTAIN_REQUEST, |
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292 | id, |
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293 | option_set, |
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294 | timeout |
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295 | ); |
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296 | case OBJECTS_LOCAL: |
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297 | if ( !_Semaphore_Seize( the_semaphore, option_set ) ) { |
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298 | if ( _Attributes_Is_inherit_priority( the_semaphore->attribute_set ) && |
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299 | the_semaphore->holder->current_priority > |
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300 | _Thread_Executing->current_priority ) { |
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301 | _Thread_Change_priority( |
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302 | the_semaphore->holder, _Thread_Executing->current_priority ); |
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303 | } |
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304 | _Thread_queue_Enqueue( &the_semaphore->Wait_queue, timeout ); |
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305 | } |
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306 | _Thread_Enable_dispatch(); |
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307 | return( _Thread_Executing->Wait.return_code ); |
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308 | } |
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309 | |
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310 | return( RTEMS_INTERNAL_ERROR ); /* unreached - only to remove warnings */ |
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311 | } |
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312 | |
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313 | /*PAGE |
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314 | * |
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315 | * rtems_semaphore_release |
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316 | * |
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317 | * This directive allows a thread to release a semaphore. |
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318 | * |
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319 | * Input parameters: |
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320 | * id - semaphore id |
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321 | * |
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322 | * Output parameters: |
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323 | * RTEMS_SUCCESSFUL - if successful |
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324 | * error code - if unsuccessful |
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325 | */ |
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326 | |
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327 | rtems_status_code rtems_semaphore_release( |
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328 | Objects_Id id |
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329 | ) |
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330 | { |
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331 | register Semaphore_Control *the_semaphore; |
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332 | Objects_Locations location; |
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333 | Thread_Control *the_thread; |
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334 | |
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335 | the_semaphore = _Semaphore_Get( id, &location ); |
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336 | switch ( location ) { |
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337 | case OBJECTS_ERROR: |
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338 | return( RTEMS_INVALID_ID ); |
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339 | case OBJECTS_REMOTE: |
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340 | return( |
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341 | _Semaphore_MP_Send_request_packet( |
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342 | SEMAPHORE_MP_RELEASE_REQUEST, |
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343 | id, |
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344 | 0, /* Not used */ |
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345 | MPCI_DEFAULT_TIMEOUT |
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346 | ) |
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347 | ); |
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348 | case OBJECTS_LOCAL: |
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349 | if ( _Attributes_Is_binary_semaphore( the_semaphore->attribute_set)) { |
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350 | |
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351 | if ( !_Objects_Are_ids_equal( |
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352 | _Thread_Executing->Object.id, the_semaphore->holder_id ) ) { |
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353 | _Thread_Enable_dispatch(); |
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354 | return( RTEMS_NOT_OWNER_OF_RESOURCE ); |
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355 | } |
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356 | |
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357 | the_semaphore->nest_count--; |
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358 | |
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359 | if ( the_semaphore->nest_count != 0 ) { |
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360 | _Thread_Enable_dispatch(); |
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361 | return( RTEMS_SUCCESSFUL ); |
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362 | } |
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363 | |
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364 | _Thread_Executing->resource_count--; |
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365 | the_semaphore->holder = NULL; |
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366 | the_semaphore->holder_id = 0; |
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367 | |
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368 | /* |
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369 | * Whether or not someone is waiting for the semaphore, an |
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370 | * inherited priority must be lowered if this is the last |
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371 | * semaphore (i.e. resource) this task has. |
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372 | */ |
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373 | |
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374 | if ( _Attributes_Is_inherit_priority(the_semaphore->attribute_set) && |
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375 | _Thread_Executing->resource_count == 0 && |
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376 | _Thread_Executing->real_priority != |
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377 | _Thread_Executing->current_priority ) { |
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378 | _Thread_Change_priority( |
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379 | _Thread_Executing, _Thread_Executing->real_priority ); |
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380 | } |
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381 | |
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382 | } |
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383 | |
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384 | if ( (the_thread = _Thread_queue_Dequeue(&the_semaphore->Wait_queue)) ) { |
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385 | |
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386 | if ( !_Objects_Is_local_id( the_thread->Object.id ) ) { |
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387 | the_thread->receive_packet->return_code = RTEMS_SUCCESSFUL; |
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388 | |
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389 | if ( _Attributes_Is_binary_semaphore(the_semaphore->attribute_set) ) { |
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390 | the_semaphore->holder = NULL; |
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391 | the_semaphore->holder_id = the_thread->Object.id; |
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392 | the_semaphore->nest_count = 1; |
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393 | } |
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394 | |
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395 | _Semaphore_MP_Send_response_packet( |
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396 | SEMAPHORE_MP_OBTAIN_RESPONSE, |
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397 | id, |
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398 | the_thread |
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399 | ); |
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400 | } else { |
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401 | |
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402 | if ( _Attributes_Is_binary_semaphore(the_semaphore->attribute_set) ) { |
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403 | the_semaphore->holder = the_thread; |
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404 | the_semaphore->holder_id = the_thread->Object.id; |
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405 | the_thread->resource_count++; |
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406 | the_semaphore->nest_count = 1; |
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407 | } |
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408 | |
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409 | /* |
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410 | * No special action for priority inheritance because the_thread |
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411 | * is guaranteed to be the highest priority thread waiting for |
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412 | * the semaphore. |
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413 | */ |
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414 | } |
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415 | } else |
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416 | the_semaphore->count += 1; |
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417 | |
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418 | _Thread_Enable_dispatch(); |
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419 | return( RTEMS_SUCCESSFUL ); |
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420 | } |
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421 | |
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422 | return( RTEMS_INTERNAL_ERROR ); /* unreached - only to remove warnings */ |
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423 | } |
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424 | |
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425 | /*PAGE |
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426 | * |
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427 | * _Semaphore_Seize |
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428 | * |
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429 | * This routine attempts to allocate a semaphore to the calling thread. |
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430 | * |
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431 | * Input parameters: |
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432 | * the_semaphore - pointer to semaphore control block |
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433 | * option_set - acquire semaphore options |
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434 | * |
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435 | * Output parameters: |
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436 | * TRUE - if semaphore allocated |
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437 | * FALSE - if semaphore NOT allocated |
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438 | * |
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439 | * INTERRUPT LATENCY: |
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440 | * available |
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441 | * wait |
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442 | */ |
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443 | |
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444 | boolean _Semaphore_Seize( |
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445 | Semaphore_Control *the_semaphore, |
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446 | rtems_option option_set |
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447 | ) |
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448 | { |
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449 | Thread_Control *executing; |
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450 | ISR_Level level; |
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451 | |
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452 | executing = _Thread_Executing; |
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453 | executing->Wait.return_code = RTEMS_SUCCESSFUL; |
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454 | _ISR_Disable( level ); |
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455 | if ( the_semaphore->count != 0 ) { |
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456 | the_semaphore->count -= 1; |
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457 | if ( _Attributes_Is_binary_semaphore( the_semaphore->attribute_set ) ) { |
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458 | the_semaphore->holder = executing; |
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459 | the_semaphore->holder_id = executing->Object.id; |
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460 | the_semaphore->nest_count = 1; |
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461 | executing->resource_count++; |
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462 | } |
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463 | _ISR_Enable( level ); |
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464 | return( TRUE ); |
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465 | } |
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466 | |
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467 | if ( _Options_Is_no_wait( option_set ) ) { |
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468 | _ISR_Enable( level ); |
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469 | executing->Wait.return_code = RTEMS_UNSATISFIED; |
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470 | return( TRUE ); |
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471 | } |
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472 | |
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473 | if ( _Attributes_Is_binary_semaphore( the_semaphore->attribute_set ) ) { |
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474 | if ( _Objects_Are_ids_equal( |
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475 | _Thread_Executing->Object.id, the_semaphore->holder_id ) ) { |
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476 | the_semaphore->nest_count++; |
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477 | _ISR_Enable( level ); |
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478 | return( TRUE ); |
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479 | } |
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480 | } |
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481 | |
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482 | the_semaphore->Wait_queue.sync = TRUE; |
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483 | executing->Wait.queue = &the_semaphore->Wait_queue; |
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484 | executing->Wait.id = the_semaphore->Object.id; |
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485 | executing->Wait.option_set = option_set; |
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486 | _ISR_Enable( level ); |
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487 | return( FALSE ); |
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488 | } |
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