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 RTEMSScoreSemaphore |
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7 | * |
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8 | * @brief This header file provides interfaces of the |
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9 | * @ref RTEMSScoreSemaphore which are only used by the implementation. |
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10 | */ |
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11 | |
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12 | /* |
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13 | * COPYRIGHT (c) 1989-2006. |
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14 | * On-Line Applications Research Corporation (OAR). |
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15 | * |
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16 | * Redistribution and use in source and binary forms, with or without |
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17 | * modification, are permitted provided that the following conditions |
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18 | * are met: |
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19 | * 1. Redistributions of source code must retain the above copyright |
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20 | * notice, this list of conditions and the following disclaimer. |
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21 | * 2. Redistributions in binary form must reproduce the above copyright |
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22 | * notice, this list of conditions and the following disclaimer in the |
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23 | * documentation and/or other materials provided with the distribution. |
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24 | * |
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25 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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26 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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27 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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28 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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29 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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30 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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31 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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32 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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33 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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34 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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35 | * POSSIBILITY OF SUCH DAMAGE. |
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36 | */ |
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37 | |
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38 | #ifndef _RTEMS_SCORE_CORESEMIMPL_H |
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39 | #define _RTEMS_SCORE_CORESEMIMPL_H |
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40 | |
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41 | #include <rtems/score/coresem.h> |
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42 | #include <rtems/score/objectimpl.h> |
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43 | #include <rtems/score/threaddispatch.h> |
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44 | #include <rtems/score/threadimpl.h> |
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45 | #include <rtems/score/threadqimpl.h> |
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46 | #include <rtems/score/statesimpl.h> |
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47 | #include <rtems/score/status.h> |
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48 | |
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49 | #ifdef __cplusplus |
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50 | extern "C" { |
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51 | #endif |
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52 | |
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53 | /** |
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54 | * @addtogroup RTEMSScoreSemaphore |
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55 | * |
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56 | * @{ |
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57 | */ |
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58 | |
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59 | /** |
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60 | * @brief Initializes the semaphore based on the parameters passed. |
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61 | * |
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62 | * This package is the implementation of the CORE Semaphore Handler. |
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63 | * This core object utilizes standard Dijkstra counting semaphores to provide |
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64 | * synchronization and mutual exclusion capabilities. |
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65 | * |
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66 | * This routine initializes the semaphore based on the parameters passed. |
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67 | * |
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68 | * @param[out] the_semaphore The semaphore to initialize. |
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69 | * @param initial_value The initial count of the semaphore. |
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70 | */ |
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71 | void _CORE_semaphore_Initialize( |
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72 | CORE_semaphore_Control *the_semaphore, |
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73 | uint32_t initial_value |
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74 | ); |
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75 | |
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76 | /** |
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77 | * @brief Acquires the semaphore critical. |
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78 | * |
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79 | * This routine acquires the semaphore. |
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80 | * |
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81 | * @param[in, out] the_semaphore The semaphore to acquire. |
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82 | * @param queue_context The thread queue context. |
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83 | */ |
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84 | static inline void _CORE_semaphore_Acquire_critical( |
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85 | CORE_semaphore_Control *the_semaphore, |
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86 | Thread_queue_Context *queue_context |
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87 | ) |
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88 | { |
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89 | _Thread_queue_Acquire_critical( &the_semaphore->Wait_queue, queue_context ); |
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90 | } |
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91 | |
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92 | /** |
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93 | * @brief Releases the semaphore. |
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94 | * |
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95 | * This routine releases the semaphore. |
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96 | * |
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97 | * @param[in, out] the_semaphore The semaphore to release. |
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98 | * @param queue_context The thread queue context. |
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99 | */ |
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100 | static inline void _CORE_semaphore_Release( |
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101 | CORE_semaphore_Control *the_semaphore, |
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102 | Thread_queue_Context *queue_context |
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103 | ) |
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104 | { |
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105 | _Thread_queue_Release( &the_semaphore->Wait_queue, queue_context ); |
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106 | } |
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107 | |
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108 | /** |
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109 | * @brief Destroys the semaphore. |
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110 | * |
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111 | * This routine destroys the semaphore. |
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112 | * |
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113 | * @param[out] the_semaphore The semaphore to destroy. |
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114 | * @param operations The thread queue operations. |
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115 | * @param queue_context The thread queue context. |
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116 | */ |
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117 | static inline void _CORE_semaphore_Destroy( |
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118 | CORE_semaphore_Control *the_semaphore, |
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119 | const Thread_queue_Operations *operations, |
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120 | Thread_queue_Context *queue_context |
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121 | ) |
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122 | { |
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123 | _Thread_queue_Flush_critical( |
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124 | &the_semaphore->Wait_queue.Queue, |
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125 | operations, |
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126 | _Thread_queue_Flush_status_object_was_deleted, |
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127 | queue_context |
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128 | ); |
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129 | _Thread_queue_Destroy( &the_semaphore->Wait_queue ); |
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130 | } |
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131 | |
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132 | /** |
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133 | * @brief Surrenders a unit to the semaphore. |
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134 | * |
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135 | * This routine frees a unit to the semaphore. If a task was blocked waiting |
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136 | * for a unit from this semaphore, then that task will be readied and the unit |
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137 | * given to that task. Otherwise, the unit will be returned to the semaphore. |
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138 | * |
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139 | * @param[in, out] the_semaphore is the semaphore to surrender |
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140 | * @param operations The thread queue operations. |
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141 | * @param maximum_count The maximum number of units in the semaphore. |
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142 | * @param queue_context is a temporary variable used to contain the ISR |
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143 | * disable level cookie. |
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144 | * |
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145 | * @retval STATUS_SUCCESSFUL The unit was successfully freed to the semaphore. |
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146 | * @retval STATUS_MAXIMUM_COUNT_EXCEEDED The maximum number of units was exceeded. |
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147 | */ |
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148 | static inline Status_Control _CORE_semaphore_Surrender( |
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149 | CORE_semaphore_Control *the_semaphore, |
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150 | const Thread_queue_Operations *operations, |
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151 | uint32_t maximum_count, |
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152 | Thread_queue_Context *queue_context |
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153 | ) |
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154 | { |
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155 | Status_Control status; |
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156 | Thread_queue_Heads *heads; |
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157 | |
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158 | status = STATUS_SUCCESSFUL; |
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159 | |
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160 | _CORE_semaphore_Acquire_critical( the_semaphore, queue_context ); |
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161 | |
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162 | heads = the_semaphore->Wait_queue.Queue.heads; |
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163 | |
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164 | if ( heads != NULL ) { |
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165 | _Thread_queue_Surrender_no_priority( |
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166 | &the_semaphore->Wait_queue.Queue, |
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167 | heads, |
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168 | queue_context, |
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169 | operations |
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170 | ); |
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171 | } else { |
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172 | if ( the_semaphore->count < maximum_count ) |
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173 | the_semaphore->count += 1; |
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174 | else |
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175 | status = STATUS_MAXIMUM_COUNT_EXCEEDED; |
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176 | |
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177 | _CORE_semaphore_Release( the_semaphore, queue_context ); |
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178 | } |
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179 | |
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180 | return status; |
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181 | } |
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182 | |
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183 | /** |
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184 | * @brief Returns the current count associated with the semaphore. |
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185 | * |
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186 | * @param the_semaphore The semaphore to obtain the count of. |
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187 | * |
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188 | * @return the current count of this semaphore. |
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189 | */ |
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190 | static inline uint32_t _CORE_semaphore_Get_count( |
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191 | const CORE_semaphore_Control *the_semaphore |
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192 | ) |
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193 | { |
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194 | return the_semaphore->count; |
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195 | } |
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196 | |
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197 | /** |
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198 | * @brief Seizes the semaphore |
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199 | * |
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200 | * This routine attempts to receive a unit from the_semaphore. |
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201 | * If a unit is available or if the wait flag is false, then the routine |
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202 | * returns. Otherwise, the calling task is blocked until a unit becomes |
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203 | * available. |
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204 | * |
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205 | * @param[in, out] the_semaphore The semaphore to obtain. |
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206 | * @param operations The thread queue operations. |
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207 | * @param executing The currently executing thread. |
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208 | * @param wait Indicates whether the calling thread is willing to wait. |
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209 | * @param queue_context is a temporary variable used to contain the ISR |
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210 | * disable level cookie. |
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211 | * |
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212 | * @retval STATUS_SUCCESSFUL The semaphore was successfully seized. |
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213 | * @retval STATUS_UNSATISFIED The semaphore is currently not free and the |
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214 | * calling thread not willing to wait. |
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215 | * @retval STATUS_TIMEOUT A timeout occurred. |
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216 | */ |
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217 | static inline Status_Control _CORE_semaphore_Seize( |
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218 | CORE_semaphore_Control *the_semaphore, |
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219 | const Thread_queue_Operations *operations, |
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220 | Thread_Control *executing, |
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221 | bool wait, |
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222 | Thread_queue_Context *queue_context |
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223 | ) |
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224 | { |
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225 | _Assert( _ISR_Get_level() != 0 ); |
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226 | |
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227 | _CORE_semaphore_Acquire_critical( the_semaphore, queue_context ); |
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228 | if ( the_semaphore->count != 0 ) { |
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229 | the_semaphore->count -= 1; |
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230 | _CORE_semaphore_Release( the_semaphore, queue_context ); |
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231 | return STATUS_SUCCESSFUL; |
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232 | } |
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233 | |
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234 | if ( !wait ) { |
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235 | _CORE_semaphore_Release( the_semaphore, queue_context ); |
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236 | return STATUS_UNSATISFIED; |
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237 | } |
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238 | |
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239 | _Thread_queue_Context_set_thread_state( |
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240 | queue_context, |
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241 | STATES_WAITING_FOR_SEMAPHORE |
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242 | ); |
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243 | _Thread_queue_Enqueue( |
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244 | &the_semaphore->Wait_queue.Queue, |
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245 | operations, |
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246 | executing, |
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247 | queue_context |
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248 | ); |
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249 | return _Thread_Wait_get_status( executing ); |
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250 | } |
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251 | |
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252 | /** @} */ |
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253 | |
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254 | #ifdef __cplusplus |
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255 | } |
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256 | #endif |
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257 | |
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258 | #endif |
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259 | /* end of include file */ |
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