2 FreeRTOS.org V4.0.5 - Copyright (C) 2003-2006 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
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 See http://www.FreeRTOS.org for documentation, latest information, license
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28 and contact details. Please ensure to read the configuration and relevant
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29 port sections of the online documentation.
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30 ***************************************************************************
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36 + Removed the volatile modifier from the function parameters. This was
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37 only ever included to prevent compiler warnings. Now warnings are
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38 removed by casting parameters where the calls are made.
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40 + prvListGetOwnerOfNextEntry() and prvListGetOwnerOfHeadEntry() have been
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41 removed from the c file and added as macros to the h file.
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43 + uxNumberOfItems has been added to the list structure. This removes the
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44 need for a pointer comparison when checking if a list is empty, and so
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47 + Removed the NULL check in vListRemove(). This makes the call faster but
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48 necessitates any application code utilising the list implementation to
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49 ensure NULL pointers are not passed.
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53 + Double linked the lists to allow faster removal item removal.
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57 + Make use of the new portBASE_TYPE definition where ever appropriate.
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61 + API changes as described on the FreeRTOS.org WEB site.
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65 + Removed the pxHead member of the xList structure. This always pointed
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66 to the same place so has been removed to free a few bytes of RAM.
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68 + Introduced the xMiniListItem structure that does not include the
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69 xListItem members that are not required by the xListEnd member of a list.
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70 Again this was done to reduce RAM usage.
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72 + Changed the volatile definitions of some structure members to clean up
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73 the code where the list structures are used.
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77 + Optimised vListInsert() in the case when the wake time is the maximum
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82 #include "FreeRTOS.h"
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85 /*-----------------------------------------------------------
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86 * PUBLIC LIST API documented in list.h
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87 *----------------------------------------------------------*/
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89 void vListInitialise( xList *pxList )
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91 /* The list structure contains a list item which is used to mark the
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92 end of the list. To initialise the list the list end is inserted
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93 as the only list entry. */
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94 pxList->pxIndex = ( xListItem * ) &( pxList->xListEnd );
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96 /* The list end value is the highest possible value in the list to
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97 ensure it remains at the end of the list. */
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98 pxList->xListEnd.xItemValue = portMAX_DELAY;
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100 /* The list end next and previous pointers point to itself so we know
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101 when the list is empty. */
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102 pxList->xListEnd.pxNext = ( xListItem * ) &( pxList->xListEnd );
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103 pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd );
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105 pxList->uxNumberOfItems = 0;
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107 /*-----------------------------------------------------------*/
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109 void vListInitialiseItem( xListItem *pxItem )
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111 /* Make sure the list item is not recorded as being on a list. */
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112 pxItem->pvContainer = NULL;
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114 /*-----------------------------------------------------------*/
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116 void vListInsertEnd( xList *pxList, xListItem *pxNewListItem )
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118 volatile xListItem * pxIndex;
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120 /* Insert a new list item into pxList, but rather than sort the list,
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121 makes the new list item the last item to be removed by a call to
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122 pvListGetOwnerOfNextEntry. This means it has to be the item pointed to by
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123 the pxIndex member. */
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124 pxIndex = pxList->pxIndex;
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126 pxNewListItem->pxNext = pxIndex->pxNext;
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127 pxNewListItem->pxPrevious = pxList->pxIndex;
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128 pxIndex->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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129 pxIndex->pxNext = ( volatile xListItem * ) pxNewListItem;
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130 pxList->pxIndex = ( volatile xListItem * ) pxNewListItem;
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132 /* Remember which list the item is in. */
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133 pxNewListItem->pvContainer = ( void * ) pxList;
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135 ( pxList->uxNumberOfItems )++;
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137 /*-----------------------------------------------------------*/
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139 void vListInsert( xList *pxList, xListItem *pxNewListItem )
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141 volatile xListItem *pxIterator;
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142 portTickType xValueOfInsertion;
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144 /* Insert the new list item into the list, sorted in ulListItem order. */
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145 xValueOfInsertion = pxNewListItem->xItemValue;
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147 /* If the list already contains a list item with the same item value then
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148 the new list item should be placed after it. This ensures that TCB's which
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149 are stored in ready lists (all of which have the same ulListItem value)
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150 get an equal share of the CPU. However, if the xItemValue is the same as
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151 the back marker the iteration loop below will not end. This means we need
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152 to guard against this by checking the value first and modifying the
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153 algorithm slightly if necessary. */
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154 if( xValueOfInsertion == portMAX_DELAY )
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156 pxIterator = pxList->xListEnd.pxPrevious;
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160 for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext )
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162 /* There is nothing to do here, we are just iterating to the
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163 wanted insertion position. */
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167 pxNewListItem->pxNext = pxIterator->pxNext;
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168 pxNewListItem->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
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169 pxNewListItem->pxPrevious = pxIterator;
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170 pxIterator->pxNext = ( volatile xListItem * ) pxNewListItem;
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172 /* Remember which list the item is in. This allows fast removal of the
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174 pxNewListItem->pvContainer = ( void * ) pxList;
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176 ( pxList->uxNumberOfItems )++;
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178 /*-----------------------------------------------------------*/
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180 void vListRemove( xListItem *pxItemToRemove )
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184 pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
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185 pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
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187 /* The list item knows which list it is in. Obtain the list from the list
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189 pxList = ( xList * ) pxItemToRemove->pvContainer;
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191 /* Make sure the index is left pointing to a valid item. */
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192 if( pxList->pxIndex == pxItemToRemove )
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194 pxList->pxIndex = pxItemToRemove->pxPrevious;
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197 pxItemToRemove->pvContainer = NULL;
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198 ( pxList->uxNumberOfItems )--;
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200 /*-----------------------------------------------------------*/
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