1 | /* |
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2 | * CORE Message Queue Handler |
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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 CORE Message Queue Handler. |
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7 | * This core object provides task synchronization and communication functions |
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8 | * via messages passed to queue objects. |
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9 | * |
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10 | * COPYRIGHT (c) 1989-2007. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * The license and distribution terms for this file may be |
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14 | * found in the file LICENSE in this distribution or at |
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15 | * http://www.rtems.com/license/LICENSE. |
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16 | * |
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17 | * $Id$ |
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18 | */ |
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19 | |
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20 | #if HAVE_CONFIG_H |
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21 | #include "config.h" |
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22 | #endif |
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23 | |
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24 | #include <rtems/system.h> |
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25 | #include <rtems/score/chain.h> |
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26 | #include <rtems/score/isr.h> |
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27 | #include <rtems/score/object.h> |
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28 | #include <rtems/score/coremsg.h> |
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29 | #include <rtems/score/states.h> |
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30 | #include <rtems/score/thread.h> |
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31 | #include <rtems/score/wkspace.h> |
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32 | |
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33 | /*PAGE |
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34 | * |
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35 | * _CORE_message_queue_Seize |
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36 | * |
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37 | * This kernel routine dequeues a message, copies the message buffer to |
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38 | * a given destination buffer, and frees the message buffer to the |
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39 | * inactive message pool. The thread will be blocked if wait is true, |
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40 | * otherwise an error will be given to the thread if no messages are available. |
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41 | * |
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42 | * Input parameters: |
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43 | * the_message_queue - pointer to message queue |
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44 | * id - id of object we are waitig on |
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45 | * buffer - pointer to message buffer to be filled |
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46 | * size_p - pointer to the size of buffer to be filled |
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47 | * wait - true if wait is allowed, false otherwise |
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48 | * timeout - time to wait for a message |
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49 | * |
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50 | * Output parameters: NONE |
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51 | * |
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52 | * NOTE: Dependent on BUFFER_LENGTH |
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53 | * |
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54 | * INTERRUPT LATENCY: |
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55 | * available |
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56 | * wait |
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57 | */ |
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58 | |
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59 | void _CORE_message_queue_Seize( |
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60 | CORE_message_queue_Control *the_message_queue, |
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61 | Objects_Id id, |
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62 | void *buffer, |
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63 | size_t *size_p, |
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64 | bool wait, |
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65 | Watchdog_Interval timeout |
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66 | ) |
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67 | { |
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68 | ISR_Level level; |
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69 | CORE_message_queue_Buffer_control *the_message; |
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70 | Thread_Control *executing; |
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71 | Thread_Control *the_thread; |
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72 | |
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73 | executing = _Thread_Executing; |
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74 | executing->Wait.return_code = CORE_MESSAGE_QUEUE_STATUS_SUCCESSFUL; |
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75 | _ISR_Disable( level ); |
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76 | the_message = _CORE_message_queue_Get_pending_message( the_message_queue ); |
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77 | if ( the_message != NULL ) { |
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78 | the_message_queue->number_of_pending_messages -= 1; |
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79 | _ISR_Enable( level ); |
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80 | |
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81 | *size_p = the_message->Contents.size; |
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82 | _Thread_Executing->Wait.count = the_message->priority; |
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83 | _CORE_message_queue_Copy_buffer(the_message->Contents.buffer,buffer,*size_p); |
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84 | |
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85 | /* |
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86 | * There could be a thread waiting to send a message. If there |
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87 | * is not, then we can go ahead and free the buffer. |
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88 | * |
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89 | * NOTE: If we note that the queue was not full before this receive, |
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90 | * then we can avoid this dequeue. |
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91 | */ |
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92 | |
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93 | the_thread = _Thread_queue_Dequeue( &the_message_queue->Wait_queue ); |
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94 | if ( !the_thread ) { |
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95 | _CORE_message_queue_Free_message_buffer( the_message_queue, the_message ); |
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96 | return; |
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97 | } |
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98 | |
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99 | /* |
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100 | * There was a thread waiting to send a message. This code |
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101 | * puts the messages in the message queue on behalf of the |
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102 | * waiting task. |
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103 | */ |
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104 | |
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105 | the_message->priority = the_thread->Wait.count; |
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106 | the_message->Contents.size = (size_t) the_thread->Wait.option; |
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107 | _CORE_message_queue_Copy_buffer( |
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108 | the_thread->Wait.return_argument_second.immutable_object, |
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109 | the_message->Contents.buffer, |
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110 | the_message->Contents.size |
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111 | ); |
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112 | |
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113 | _CORE_message_queue_Insert_message( |
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114 | the_message_queue, |
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115 | the_message, |
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116 | the_message->priority |
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117 | ); |
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118 | return; |
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119 | } |
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120 | |
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121 | if ( !wait ) { |
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122 | _ISR_Enable( level ); |
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123 | executing->Wait.return_code = CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED_NOWAIT; |
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124 | return; |
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125 | } |
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126 | |
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127 | _Thread_queue_Enter_critical_section( &the_message_queue->Wait_queue ); |
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128 | executing->Wait.queue = &the_message_queue->Wait_queue; |
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129 | executing->Wait.id = id; |
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130 | executing->Wait.return_argument_second.mutable_object = buffer; |
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131 | executing->Wait.return_argument = size_p; |
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132 | /* Wait.count will be filled in with the message priority */ |
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133 | _ISR_Enable( level ); |
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134 | |
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135 | _Thread_queue_Enqueue( &the_message_queue->Wait_queue, timeout ); |
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136 | } |
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