2 FreeRTOS V7.2.0 - Copyright (C) 2012 Real Time Engineers Ltd.
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5 ***************************************************************************
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7 * FreeRTOS tutorial books are available in pdf and paperback. *
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8 * Complete, revised, and edited pdf reference manuals are also *
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11 * Purchasing FreeRTOS documentation will not only help you, by *
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12 * ensuring you get running as quickly as possible and with an *
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13 * in-depth knowledge of how to use FreeRTOS, it will also help *
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14 * the FreeRTOS project to continue with its mission of providing *
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15 * professional grade, cross platform, de facto standard solutions *
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16 * for microcontrollers - completely free of charge! *
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18 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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20 * Thank you for using FreeRTOS, and thank you for your support! *
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22 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 >>>NOTE<<< The modification to the GPL is included to allow you to
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31 distribute a combined work that includes FreeRTOS without being obliged to
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32 provide the source code for proprietary components outside of the FreeRTOS
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33 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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34 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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35 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 ***************************************************************************
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46 * Having a problem? Start by reading the FAQ "My application does *
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47 * not run, what could be wrong? *
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49 * http://www.FreeRTOS.org/FAQHelp.html *
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51 ***************************************************************************
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54 http://www.FreeRTOS.org - Documentation, training, latest information,
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55 license and contact details.
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57 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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58 including FreeRTOS+Trace - an indispensable productivity tool.
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60 Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
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61 the code with commercial support, indemnification, and middleware, under
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62 the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
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63 provide a safety engineered and independently SIL3 certified version under
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64 the SafeRTOS brand: http://www.SafeRTOS.com.
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69 #include "FreeRTOS.h"
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72 /*-----------------------------------------------------------
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73 * PUBLIC LIST API documented in list.h
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74 *----------------------------------------------------------*/
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76 void vListInitialise( xList *pxList )
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78 /* The list structure contains a list item which is used to mark the
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79 end of the list. To initialise the list the list end is inserted
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80 as the only list entry. */
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81 pxList->pxIndex = ( xListItem * ) &( pxList->xListEnd );
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83 /* The list end value is the highest possible value in the list to
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84 ensure it remains at the end of the list. */
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85 pxList->xListEnd.xItemValue = portMAX_DELAY;
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87 /* The list end next and previous pointers point to itself so we know
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88 when the list is empty. */
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89 pxList->xListEnd.pxNext = ( xListItem * ) &( pxList->xListEnd );
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90 pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd );
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92 pxList->uxNumberOfItems = ( unsigned portBASE_TYPE ) 0U;
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94 /*-----------------------------------------------------------*/
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96 void vListInitialiseItem( xListItem *pxItem )
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98 /* Make sure the list item is not recorded as being on a list. */
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99 pxItem->pvContainer = NULL;
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101 /*-----------------------------------------------------------*/
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103 void vListInsertEnd( xList *pxList, xListItem *pxNewListItem )
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105 volatile xListItem * pxIndex;
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107 /* Insert a new list item into pxList, but rather than sort the list,
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108 makes the new list item the last item to be removed by a call to
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109 pvListGetOwnerOfNextEntry. This means it has to be the item pointed to by
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110 the pxIndex member. */
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111 pxIndex = pxList->pxIndex;
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113 pxNewListItem->pxNext = pxIndex->pxNext;
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114 pxNewListItem->pxPrevious = pxList->pxIndex;
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115 pxIndex->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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116 pxIndex->pxNext = ( volatile xListItem * ) pxNewListItem;
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117 pxList->pxIndex = ( volatile xListItem * ) pxNewListItem;
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119 /* Remember which list the item is in. */
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120 pxNewListItem->pvContainer = ( void * ) pxList;
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122 ( pxList->uxNumberOfItems )++;
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124 /*-----------------------------------------------------------*/
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126 void vListInsert( xList *pxList, xListItem *pxNewListItem )
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128 volatile xListItem *pxIterator;
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129 portTickType xValueOfInsertion;
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131 /* Insert the new list item into the list, sorted in ulListItem order. */
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132 xValueOfInsertion = pxNewListItem->xItemValue;
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134 /* If the list already contains a list item with the same item value then
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135 the new list item should be placed after it. This ensures that TCB's which
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136 are stored in ready lists (all of which have the same ulListItem value)
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137 get an equal share of the CPU. However, if the xItemValue is the same as
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138 the back marker the iteration loop below will not end. This means we need
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139 to guard against this by checking the value first and modifying the
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140 algorithm slightly if necessary. */
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141 if( xValueOfInsertion == portMAX_DELAY )
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143 pxIterator = pxList->xListEnd.pxPrevious;
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147 /* *** NOTE ***********************************************************
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148 If you find your application is crashing here then likely causes are:
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149 1) Stack overflow -
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150 see http://www.freertos.org/Stacks-and-stack-overflow-checking.html
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151 2) Incorrect interrupt priority assignment, especially on Cortex-M3
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152 parts where numerically high priority values denote low actual
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153 interrupt priories, which can seem counter intuitive. See
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154 configMAX_SYSCALL_INTERRUPT_PRIORITY on http://www.freertos.org/a00110.html
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155 3) Calling an API function from within a critical section or when
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156 the scheduler is suspended.
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157 4) Using a queue or semaphore before it has been initialised or
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158 before the scheduler has been started (are interrupts firing
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159 before vTaskStartScheduler() has been called?).
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160 See http://www.freertos.org/FAQHelp.html for more tips.
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161 **********************************************************************/
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163 for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext )
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165 /* There is nothing to do here, we are just iterating to the
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166 wanted insertion position. */
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170 pxNewListItem->pxNext = pxIterator->pxNext;
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171 pxNewListItem->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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172 pxNewListItem->pxPrevious = pxIterator;
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173 pxIterator->pxNext = ( volatile xListItem * ) pxNewListItem;
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175 /* Remember which list the item is in. This allows fast removal of the
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177 pxNewListItem->pvContainer = ( void * ) pxList;
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179 ( pxList->uxNumberOfItems )++;
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181 /*-----------------------------------------------------------*/
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183 void vListRemove( xListItem *pxItemToRemove )
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187 pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
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188 pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
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190 /* The list item knows which list it is in. Obtain the list from the list
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192 pxList = ( xList * ) pxItemToRemove->pvContainer;
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194 /* Make sure the index is left pointing to a valid item. */
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195 if( pxList->pxIndex == pxItemToRemove )
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197 pxList->pxIndex = pxItemToRemove->pxPrevious;
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200 pxItemToRemove->pvContainer = NULL;
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201 ( pxList->uxNumberOfItems )--;
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203 /*-----------------------------------------------------------*/
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