2 FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS books - available as PDF or paperback *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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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 exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 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 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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56 #include "FreeRTOS.h"
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59 /*-----------------------------------------------------------
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60 * PUBLIC LIST API documented in list.h
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61 *----------------------------------------------------------*/
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63 void vListInitialise( xList *pxList )
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65 /* The list structure contains a list item which is used to mark the
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66 end of the list. To initialise the list the list end is inserted
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67 as the only list entry. */
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68 pxList->pxIndex = ( xListItem * ) &( pxList->xListEnd );
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70 /* The list end value is the highest possible value in the list to
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71 ensure it remains at the end of the list. */
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72 pxList->xListEnd.xItemValue = portMAX_DELAY;
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74 /* The list end next and previous pointers point to itself so we know
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75 when the list is empty. */
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76 pxList->xListEnd.pxNext = ( xListItem * ) &( pxList->xListEnd );
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77 pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd );
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79 pxList->uxNumberOfItems = 0;
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81 /*-----------------------------------------------------------*/
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83 void vListInitialiseItem( xListItem *pxItem )
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85 /* Make sure the list item is not recorded as being on a list. */
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86 pxItem->pvContainer = NULL;
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88 /*-----------------------------------------------------------*/
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90 void vListInsertEnd( xList *pxList, xListItem *pxNewListItem )
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92 volatile xListItem * pxIndex;
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94 /* Insert a new list item into pxList, but rather than sort the list,
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95 makes the new list item the last item to be removed by a call to
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96 pvListGetOwnerOfNextEntry. This means it has to be the item pointed to by
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97 the pxIndex member. */
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98 pxIndex = pxList->pxIndex;
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100 pxNewListItem->pxNext = pxIndex->pxNext;
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101 pxNewListItem->pxPrevious = pxList->pxIndex;
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102 pxIndex->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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103 pxIndex->pxNext = ( volatile xListItem * ) pxNewListItem;
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104 pxList->pxIndex = ( volatile xListItem * ) pxNewListItem;
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106 /* Remember which list the item is in. */
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107 pxNewListItem->pvContainer = ( void * ) pxList;
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109 ( pxList->uxNumberOfItems )++;
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111 /*-----------------------------------------------------------*/
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113 void vListInsert( xList *pxList, xListItem *pxNewListItem )
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115 volatile xListItem *pxIterator;
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116 portTickType xValueOfInsertion;
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118 /* Insert the new list item into the list, sorted in ulListItem order. */
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119 xValueOfInsertion = pxNewListItem->xItemValue;
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121 /* If the list already contains a list item with the same item value then
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122 the new list item should be placed after it. This ensures that TCB's which
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123 are stored in ready lists (all of which have the same ulListItem value)
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124 get an equal share of the CPU. However, if the xItemValue is the same as
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125 the back marker the iteration loop below will not end. This means we need
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126 to guard against this by checking the value first and modifying the
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127 algorithm slightly if necessary. */
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128 if( xValueOfInsertion == portMAX_DELAY )
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130 pxIterator = pxList->xListEnd.pxPrevious;
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134 /* *** NOTE ***********************************************************
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135 If you find your application is crashing here then likely causes are:
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136 1) Stack overflow -
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137 see http://www.freertos.org/Stacks-and-stack-overflow-checking.html
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138 2) Incorrect interrupt priority assignment, especially on Cortex M3
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139 parts where numerically high priority values denote low actual
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140 interrupt priories, which can seem counter intuitive. See
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141 configMAX_SYSCALL_INTERRUPT_PRIORITY on http://www.freertos.org/a00110.html
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142 3) Calling an API function from within a critical section or when
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143 the scheduler is suspended.
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144 4) Using a queue or semaphore before it has been initialised or
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145 before the scheduler has been started (are interrupts firing
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146 before vTaskStartScheduler() has been called?).
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147 See http://www.freertos.org/FAQHelp.html for more tips.
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148 **********************************************************************/
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150 for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext )
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152 /* There is nothing to do here, we are just iterating to the
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153 wanted insertion position. */
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157 pxNewListItem->pxNext = pxIterator->pxNext;
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158 pxNewListItem->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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159 pxNewListItem->pxPrevious = pxIterator;
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160 pxIterator->pxNext = ( volatile xListItem * ) pxNewListItem;
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162 /* Remember which list the item is in. This allows fast removal of the
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164 pxNewListItem->pvContainer = ( void * ) pxList;
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166 ( pxList->uxNumberOfItems )++;
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168 /*-----------------------------------------------------------*/
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170 void vListRemove( xListItem *pxItemToRemove )
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174 pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
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175 pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
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177 /* The list item knows which list it is in. Obtain the list from the list
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179 pxList = ( xList * ) pxItemToRemove->pvContainer;
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181 /* Make sure the index is left pointing to a valid item. */
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182 if( pxList->pxIndex == pxItemToRemove )
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184 pxList->pxIndex = pxItemToRemove->pxPrevious;
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187 pxItemToRemove->pvContainer = NULL;
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188 ( pxList->uxNumberOfItems )--;
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190 /*-----------------------------------------------------------*/
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