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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53 * A sample implementation of pvPortMalloc() and vPortFree() that permits
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54 * allocated blocks to be freed, but does not combine adjacent free blocks
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55 * into a single larger block.
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57 * See heap_1.c and heap_3.c for alternative implementations, and the memory
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58 * management pages of http://www.FreeRTOS.org for more information.
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62 #include "FreeRTOS.h"
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65 /* Setup the correct byte alignment mask for the defined byte alignment. */
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67 #if portBYTE_ALIGNMENT == 8
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68 #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0007 )
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71 #if portBYTE_ALIGNMENT == 4
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72 #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0003 )
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75 #if portBYTE_ALIGNMENT == 2
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76 #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0001 )
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79 #if portBYTE_ALIGNMENT == 1
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80 #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0000 )
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83 #ifndef heapBYTE_ALIGNMENT_MASK
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84 #error "Invalid portBYTE_ALIGNMENT definition"
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87 /* Allocate the memory for the heap. The struct is used to force byte
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88 alignment without using any non-portable code. */
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89 static union xRTOS_HEAP
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91 volatile unsigned portLONG ulDummy;
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92 unsigned portCHAR ucHeap[ configTOTAL_HEAP_SIZE ];
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95 /* Define the linked list structure. This is used to link free blocks in order
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97 typedef struct A_BLOCK_LINK
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99 struct A_BLOCK_LINK *pxNextFreeBlock; /*<< The next free block in the list. */
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100 size_t xBlockSize; /*<< The size of the free block. */
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104 static const unsigned portSHORT heapSTRUCT_SIZE = ( sizeof( xBlockLink ) + ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );
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105 #define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )
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107 /* Create a couple of list links to mark the start and end of the list. */
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108 static xBlockLink xStart, xEnd;
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110 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */
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113 * Insert a block into the list of free blocks - which is ordered by size of
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114 * the block. Small blocks at the start of the list and large blocks at the end
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117 #define prvInsertBlockIntoFreeList( pxBlockToInsert ) \
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119 xBlockLink *pxIterator; \
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120 size_t xBlockSize; \
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122 xBlockSize = pxBlockToInsert->xBlockSize; \
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124 /* Iterate through the list until a block is found that has a larger size */ \
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125 /* than the block we are inserting. */ \
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126 for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \
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128 /* There is nothing to do here - just iterate to the correct position. */ \
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131 /* Update the list to include the block being inserted in the correct */ \
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133 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock; \
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134 pxIterator->pxNextFreeBlock = pxBlockToInsert; \
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136 /*-----------------------------------------------------------*/
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138 #define prvHeapInit() \
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140 xBlockLink *pxFirstFreeBlock; \
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142 /* xStart is used to hold a pointer to the first item in the list of free */ \
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143 /* blocks. The void cast is used to prevent compiler warnings. */ \
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144 xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap; \
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145 xStart.xBlockSize = ( size_t ) 0; \
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147 /* xEnd is used to mark the end of the list of free blocks. */ \
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148 xEnd.xBlockSize = configTOTAL_HEAP_SIZE; \
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149 xEnd.pxNextFreeBlock = NULL; \
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151 /* To start with there is a single free block that is sized to take up the \
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152 entire heap space. */ \
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153 pxFirstFreeBlock = ( void * ) xHeap.ucHeap; \
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154 pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE; \
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155 pxFirstFreeBlock->pxNextFreeBlock = &xEnd; \
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157 /*-----------------------------------------------------------*/
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159 void *pvPortMalloc( size_t xWantedSize )
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161 xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;
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162 static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;
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163 void *pvReturn = NULL;
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167 /* If this is the first call to malloc then the heap will require
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168 initialisation to setup the list of free blocks. */
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169 if( xHeapHasBeenInitialised == pdFALSE )
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172 xHeapHasBeenInitialised = pdTRUE;
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175 /* The wanted size is increased so it can contain a xBlockLink
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176 structure in addition to the requested amount of bytes. */
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177 if( xWantedSize > 0 )
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179 xWantedSize += heapSTRUCT_SIZE;
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181 /* Ensure that blocks are always aligned to the required number of bytes. */
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182 if( xWantedSize & heapBYTE_ALIGNMENT_MASK )
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184 /* Byte alignment required. */
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185 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & heapBYTE_ALIGNMENT_MASK ) );
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189 if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )
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191 /* Blocks are stored in byte order - traverse the list from the start
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192 (smallest) block until one of adequate size is found. */
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193 pxPreviousBlock = &xStart;
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194 pxBlock = xStart.pxNextFreeBlock;
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195 while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )
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197 pxPreviousBlock = pxBlock;
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198 pxBlock = pxBlock->pxNextFreeBlock;
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201 /* If we found the end marker then a block of adequate size was not found. */
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202 if( pxBlock != &xEnd )
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204 /* Return the memory space - jumping over the xBlockLink structure
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206 pvReturn = ( void * ) ( ( ( unsigned portCHAR * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );
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208 /* This block is being returned for use so must be taken our of the
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209 list of free blocks. */
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210 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;
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212 /* If the block is larger than required it can be split into two. */
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213 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
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215 /* This block is to be split into two. Create a new block
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216 following the number of bytes requested. The void cast is
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217 used to prevent byte alignment warnings from the compiler. */
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218 pxNewBlockLink = ( void * ) ( ( ( unsigned portCHAR * ) pxBlock ) + xWantedSize );
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220 /* Calculate the sizes of two blocks split from the single
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222 pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
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223 pxBlock->xBlockSize = xWantedSize;
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225 /* Insert the new block into the list of free blocks. */
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226 prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
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235 /*-----------------------------------------------------------*/
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237 void vPortFree( void *pv )
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239 unsigned portCHAR *puc = ( unsigned portCHAR * ) pv;
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240 xBlockLink *pxLink;
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244 /* The memory being freed will have an xBlockLink structure immediately
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246 puc -= heapSTRUCT_SIZE;
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248 /* This casting is to keep the compiler from issuing warnings. */
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249 pxLink = ( void * ) puc;
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253 /* Add this block to the list of free blocks. */
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254 prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );
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259 /*-----------------------------------------------------------*/
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