00001 /* 00002 FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd. 00003 00004 *************************************************************************** 00005 * * 00006 * If you are: * 00007 * * 00008 * + New to FreeRTOS, * 00009 * + Wanting to learn FreeRTOS or multitasking in general quickly * 00010 * + Looking for basic training, * 00011 * + Wanting to improve your FreeRTOS skills and productivity * 00012 * * 00013 * then take a look at the FreeRTOS eBook * 00014 * * 00015 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" * 00016 * http://www.FreeRTOS.org/Documentation * 00017 * * 00018 * A pdf reference manual is also available. Both are usually delivered * 00019 * to your inbox within 20 minutes to two hours when purchased between 8am * 00020 * and 8pm GMT (although please allow up to 24 hours in case of * 00021 * exceptional circumstances). Thank you for your support! * 00022 * * 00023 *************************************************************************** 00024 00025 This file is part of the FreeRTOS distribution. 00026 00027 FreeRTOS is free software; you can redistribute it and/or modify it under 00028 the terms of the GNU General Public License (version 2) as published by the 00029 Free Software Foundation AND MODIFIED BY the FreeRTOS exception. 00030 ***NOTE*** The exception to the GPL is included to allow you to distribute 00031 a combined work that includes FreeRTOS without being obliged to provide the 00032 source code for proprietary components outside of the FreeRTOS kernel. 00033 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT 00034 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 00035 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 00036 more details. You should have received a copy of the GNU General Public 00037 License and the FreeRTOS license exception along with FreeRTOS; if not it 00038 can be viewed here: http://www.freertos.org/a00114.html and also obtained 00039 by writing to Richard Barry, contact details for whom are available on the 00040 FreeRTOS WEB site. 00041 00042 1 tab == 4 spaces! 00043 00044 http://www.FreeRTOS.org - Documentation, latest information, license and 00045 contact details. 00046 00047 http://www.SafeRTOS.com - A version that is certified for use in safety 00048 critical systems. 00049 00050 http://www.OpenRTOS.com - Commercial support, development, porting, 00051 licensing and training services. 00052 */ 00053 00054 00055 #include <stdlib.h> 00056 #include "FreeRTOS.h" 00057 #include "list.h" 00058 00059 /*----------------------------------------------------------- 00060 * PUBLIC LIST API documented in list.h 00061 *----------------------------------------------------------*/ 00062 00063 void vListInitialise( xList *pxList ) 00064 { 00065 /* The list structure contains a list item which is used to mark the 00066 end of the list. To initialise the list the list end is inserted 00067 as the only list entry. */ 00068 pxList->pxIndex = ( xListItem * ) &( pxList->xListEnd ); 00069 00070 /* The list end value is the highest possible value in the list to 00071 ensure it remains at the end of the list. */ 00072 pxList->xListEnd.xItemValue = portMAX_DELAY; 00073 00074 /* The list end next and previous pointers point to itself so we know 00075 when the list is empty. */ 00076 pxList->xListEnd.pxNext = ( xListItem * ) &( pxList->xListEnd ); 00077 pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd ); 00078 00079 pxList->uxNumberOfItems = 0; 00080 } 00081 /*-----------------------------------------------------------*/ 00082 00083 void vListInitialiseItem( xListItem *pxItem ) 00084 { 00085 /* Make sure the list item is not recorded as being on a list. */ 00086 pxItem->pvContainer = NULL; 00087 } 00088 /*-----------------------------------------------------------*/ 00089 00090 void vListInsertEnd( xList *pxList, xListItem *pxNewListItem ) 00091 { 00092 volatile xListItem * pxIndex; 00093 00094 /* Insert a new list item into pxList, but rather than sort the list, 00095 makes the new list item the last item to be removed by a call to 00096 pvListGetOwnerOfNextEntry. This means it has to be the item pointed to by 00097 the pxIndex member. */ 00098 pxIndex = pxList->pxIndex; 00099 00100 pxNewListItem->pxNext = pxIndex->pxNext; 00101 pxNewListItem->pxPrevious = pxList->pxIndex; 00102 pxIndex->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem; 00103 pxIndex->pxNext = ( volatile xListItem * ) pxNewListItem; 00104 pxList->pxIndex = ( volatile xListItem * ) pxNewListItem; 00105 00106 /* Remember which list the item is in. */ 00107 pxNewListItem->pvContainer = ( void * ) pxList; 00108 00109 ( pxList->uxNumberOfItems )++; 00110 } 00111 /*-----------------------------------------------------------*/ 00112 00113 void vListInsert( xList *pxList, xListItem *pxNewListItem ) 00114 { 00115 volatile xListItem *pxIterator; 00116 portTickType xValueOfInsertion; 00117 00118 /* Insert the new list item into the list, sorted in ulListItem order. */ 00119 xValueOfInsertion = pxNewListItem->xItemValue; 00120 00121 /* If the list already contains a list item with the same item value then 00122 the new list item should be placed after it. This ensures that TCB's which 00123 are stored in ready lists (all of which have the same ulListItem value) 00124 get an equal share of the CPU. However, if the xItemValue is the same as 00125 the back marker the iteration loop below will not end. This means we need 00126 to guard against this by checking the value first and modifying the 00127 algorithm slightly if necessary. */ 00128 if( xValueOfInsertion == portMAX_DELAY ) 00129 { 00130 pxIterator = pxList->xListEnd.pxPrevious; 00131 } 00132 else 00133 { 00134 /* *** NOTE *********************************************************** 00135 If you find your application is crashing here then likely causes are: 00136 1) Stack overflow - 00137 see http://www.freertos.org/Stacks-and-stack-overflow-checking.html 00138 2) Incorrect interrupt priority assignment, especially on Cortex M3 00139 parts where numerically high priority values denote low actual 00140 interrupt priories, which can seem counter intuitive. See 00141 configMAX_SYSCALL_INTERRUPT_PRIORITY on http://www.freertos.org/a00110.html 00142 3) Calling an API function from within a critical section or when 00143 the scheduler is suspended. 00144 4) Using a queue or semaphore before it has been initialised or 00145 before the scheduler has been started (are interrupts firing 00146 before vTaskStartScheduler() has been called?). 00147 See http://www.freertos.org/FAQHelp.html for more tips. 00148 **********************************************************************/ 00149 00150 for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext ) 00151 { 00152 /* There is nothing to do here, we are just iterating to the 00153 wanted insertion position. */ 00154 } 00155 } 00156 00157 pxNewListItem->pxNext = pxIterator->pxNext; 00158 pxNewListItem->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem; 00159 pxNewListItem->pxPrevious = pxIterator; 00160 pxIterator->pxNext = ( volatile xListItem * ) pxNewListItem; 00161 00162 /* Remember which list the item is in. This allows fast removal of the 00163 item later. */ 00164 pxNewListItem->pvContainer = ( void * ) pxList; 00165 00166 ( pxList->uxNumberOfItems )++; 00167 } 00168 /*-----------------------------------------------------------*/ 00169 00170 void vListRemove( xListItem *pxItemToRemove ) 00171 { 00172 xList * pxList; 00173 00174 pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious; 00175 pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext; 00176 00177 /* The list item knows which list it is in. Obtain the list from the list 00178 item. */ 00179 pxList = ( xList * ) pxItemToRemove->pvContainer; 00180 00181 /* Make sure the index is left pointing to a valid item. */ 00182 if( pxList->pxIndex == pxItemToRemove ) 00183 { 00184 pxList->pxIndex = pxItemToRemove->pxPrevious; 00185 } 00186 00187 pxItemToRemove->pvContainer = NULL; 00188 ( pxList->uxNumberOfItems )--; 00189 } 00190 /*-----------------------------------------------------------*/ 00191