2 FreeRTOS.org V5.3.1 - Copyright (C) 2003-2009 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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54 #include "FreeRTOS.h"
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57 /*-----------------------------------------------------------
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58 * PUBLIC LIST API documented in list.h
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59 *----------------------------------------------------------*/
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61 void vListInitialise( xList *pxList )
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63 /* The list structure contains a list item which is used to mark the
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64 end of the list. To initialise the list the list end is inserted
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65 as the only list entry. */
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66 pxList->pxIndex = ( xListItem * ) &( pxList->xListEnd );
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68 /* The list end value is the highest possible value in the list to
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69 ensure it remains at the end of the list. */
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70 pxList->xListEnd.xItemValue = portMAX_DELAY;
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72 /* The list end next and previous pointers point to itself so we know
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73 when the list is empty. */
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74 pxList->xListEnd.pxNext = ( xListItem * ) &( pxList->xListEnd );
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75 pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd );
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77 pxList->uxNumberOfItems = 0;
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79 /*-----------------------------------------------------------*/
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81 void vListInitialiseItem( xListItem *pxItem )
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83 /* Make sure the list item is not recorded as being on a list. */
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84 pxItem->pvContainer = NULL;
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86 /*-----------------------------------------------------------*/
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88 void vListInsertEnd( xList *pxList, xListItem *pxNewListItem )
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90 volatile xListItem * pxIndex;
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92 /* Insert a new list item into pxList, but rather than sort the list,
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93 makes the new list item the last item to be removed by a call to
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94 pvListGetOwnerOfNextEntry. This means it has to be the item pointed to by
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95 the pxIndex member. */
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96 pxIndex = pxList->pxIndex;
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98 pxNewListItem->pxNext = pxIndex->pxNext;
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99 pxNewListItem->pxPrevious = pxList->pxIndex;
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100 pxIndex->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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101 pxIndex->pxNext = ( volatile xListItem * ) pxNewListItem;
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102 pxList->pxIndex = ( volatile xListItem * ) pxNewListItem;
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104 /* Remember which list the item is in. */
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105 pxNewListItem->pvContainer = ( void * ) pxList;
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107 ( pxList->uxNumberOfItems )++;
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109 /*-----------------------------------------------------------*/
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111 void vListInsert( xList *pxList, xListItem *pxNewListItem )
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113 volatile xListItem *pxIterator;
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114 portTickType xValueOfInsertion;
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116 /* Insert the new list item into the list, sorted in ulListItem order. */
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117 xValueOfInsertion = pxNewListItem->xItemValue;
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119 /* If the list already contains a list item with the same item value then
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120 the new list item should be placed after it. This ensures that TCB's which
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121 are stored in ready lists (all of which have the same ulListItem value)
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122 get an equal share of the CPU. However, if the xItemValue is the same as
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123 the back marker the iteration loop below will not end. This means we need
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124 to guard against this by checking the value first and modifying the
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125 algorithm slightly if necessary. */
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126 if( xValueOfInsertion == portMAX_DELAY )
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128 pxIterator = pxList->xListEnd.pxPrevious;
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132 /* *** NOTE ***********************************************************
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133 If you find your application is crashing here then likely causes are:
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134 1) Stack overflow -
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135 see http://www.freertos.org/Stacks-and-stack-overflow-checking.html
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136 2) Incorrect interrupt priority assignment, especially on Cortex M3
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137 parts where numerically high priority values denote low actual
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138 interrupt priories, which can seem counter intuitive. See
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139 configMAX_SYSCALL_INTERRUPT_PRIORITY on http://www.freertos.org/a00110.html
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140 3) Calling an API function from within a critical section or when
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141 the scheduler is suspended.
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142 4) Using a queue or semaphore before it has been initialised or
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143 before the scheduler has been started (are interrupts firing
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144 before vTaskStartScheduler() has been called?).
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145 See http://www.freertos.org/FAQHelp.html for more tips.
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146 **********************************************************************/
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148 for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext )
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150 /* There is nothing to do here, we are just iterating to the
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151 wanted insertion position. */
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155 pxNewListItem->pxNext = pxIterator->pxNext;
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156 pxNewListItem->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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157 pxNewListItem->pxPrevious = pxIterator;
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158 pxIterator->pxNext = ( volatile xListItem * ) pxNewListItem;
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160 /* Remember which list the item is in. This allows fast removal of the
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162 pxNewListItem->pvContainer = ( void * ) pxList;
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164 ( pxList->uxNumberOfItems )++;
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166 /*-----------------------------------------------------------*/
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168 void vListRemove( xListItem *pxItemToRemove )
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172 pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
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173 pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
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175 /* The list item knows which list it is in. Obtain the list from the list
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177 pxList = ( xList * ) pxItemToRemove->pvContainer;
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179 /* Make sure the index is left pointing to a valid item. */
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180 if( pxList->pxIndex == pxItemToRemove )
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182 pxList->pxIndex = pxItemToRemove->pxPrevious;
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185 pxItemToRemove->pvContainer = NULL;
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186 ( pxList->uxNumberOfItems )--;
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188 /*-----------------------------------------------------------*/
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