2 FreeRTOS V7.5.2 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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6 ***************************************************************************
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8 * FreeRTOS provides completely free yet professionally developed, *
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9 * robust, strictly quality controlled, supported, and cross *
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10 * platform software that has become a de facto standard. *
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12 * Help yourself get started quickly and support the FreeRTOS *
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13 * project by purchasing a FreeRTOS tutorial book, reference *
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14 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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18 ***************************************************************************
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20 This file is part of the FreeRTOS distribution.
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22 FreeRTOS is free software; you can redistribute it and/or modify it under
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23 the terms of the GNU General Public License (version 2) as published by the
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24 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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26 >>! NOTE: The modification to the GPL is included to allow you to distribute
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27 >>! a combined work that includes FreeRTOS without being obliged to provide
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28 >>! the source code for proprietary components outside of the FreeRTOS
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31 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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32 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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33 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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34 link: http://www.freertos.org/a00114.html
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38 ***************************************************************************
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40 * Having a problem? Start by reading the FAQ "My application does *
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41 * not run, what could be wrong?" *
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43 * http://www.FreeRTOS.org/FAQHelp.html *
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45 ***************************************************************************
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47 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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48 license and Real Time Engineers Ltd. contact details.
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50 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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51 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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52 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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54 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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55 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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56 licenses offer ticketed support, indemnification and middleware.
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58 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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59 engineered and independently SIL3 certified version for use in safety and
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60 mission critical applications that require provable dependability.
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66 * A sample implementation of pvPortMalloc() and vPortFree() that combines
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67 * (coalescences) adjacent memory blocks as they are freed, and in so doing
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68 * limits memory fragmentation.
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70 * See heap_1.c, heap_2.c and heap_3.c for alternative implementations, and the
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71 * memory management pages of http://www.FreeRTOS.org for more information.
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75 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
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76 all the API functions to use the MPU wrappers. That should only be done when
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77 task.h is included from an application file. */
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78 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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80 #include "FreeRTOS.h"
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83 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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85 /* Block sizes must not get too small. */
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86 #define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )
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88 /* Assumes 8bit bytes! */
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89 #define heapBITS_PER_BYTE ( ( size_t ) 8 )
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91 /* A few bytes might be lost to byte aligning the heap start address. */
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92 #define heapADJUSTED_HEAP_SIZE ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )
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94 /* Allocate the memory for the heap. */
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95 static unsigned char ucHeap[ configTOTAL_HEAP_SIZE ];
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97 /* Define the linked list structure. This is used to link free blocks in order
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98 of their memory address. */
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99 typedef struct A_BLOCK_LINK
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101 struct A_BLOCK_LINK *pxNextFreeBlock; /*<< The next free block in the list. */
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102 size_t xBlockSize; /*<< The size of the free block. */
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105 /*-----------------------------------------------------------*/
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108 * Inserts a block of memory that is being freed into the correct position in
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109 * the list of free memory blocks. The block being freed will be merged with
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110 * the block in front it and/or the block behind it if the memory blocks are
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111 * adjacent to each other.
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113 static void prvInsertBlockIntoFreeList( xBlockLink *pxBlockToInsert );
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116 * Called automatically to setup the required heap structures the first time
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117 * pvPortMalloc() is called.
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119 static void prvHeapInit( void );
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121 /*-----------------------------------------------------------*/
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123 /* The size of the structure placed at the beginning of each allocated memory
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124 block must by correctly byte aligned. */
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125 static const unsigned short heapSTRUCT_SIZE = ( ( sizeof ( xBlockLink ) + ( portBYTE_ALIGNMENT - 1 ) ) & ~portBYTE_ALIGNMENT_MASK );
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127 /* Ensure the pxEnd pointer will end up on the correct byte alignment. */
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128 static const size_t xTotalHeapSize = ( ( size_t ) heapADJUSTED_HEAP_SIZE ) & ( ( size_t ) ~portBYTE_ALIGNMENT_MASK );
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130 /* Create a couple of list links to mark the start and end of the list. */
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131 static xBlockLink xStart, *pxEnd = NULL;
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133 /* Keeps track of the number of free bytes remaining, but says nothing about
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135 static size_t xFreeBytesRemaining = ( ( size_t ) heapADJUSTED_HEAP_SIZE ) & ( ( size_t ) ~portBYTE_ALIGNMENT_MASK );
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137 /* Gets set to the top bit of an size_t type. When this bit in the xBlockSize
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138 member of an xBlockLink structure is set then the block belongs to the
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139 application. When the bit is free the block is still part of the free heap
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141 static size_t xBlockAllocatedBit = 0;
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143 /*-----------------------------------------------------------*/
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145 void *pvPortMalloc( size_t xWantedSize )
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147 xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;
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148 void *pvReturn = NULL;
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152 /* If this is the first call to malloc then the heap will require
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153 initialisation to setup the list of free blocks. */
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154 if( pxEnd == NULL )
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159 /* Check the requested block size is not so large that the top bit is
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160 set. The top bit of the block size member of the xBlockLink structure
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161 is used to determine who owns the block - the application or the
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162 kernel, so it must be free. */
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163 if( ( xWantedSize & xBlockAllocatedBit ) == 0 )
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165 /* The wanted size is increased so it can contain a xBlockLink
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166 structure in addition to the requested amount of bytes. */
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167 if( xWantedSize > 0 )
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169 xWantedSize += heapSTRUCT_SIZE;
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171 /* Ensure that blocks are always aligned to the required number
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173 if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )
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175 /* Byte alignment required. */
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176 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
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180 if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
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182 /* Traverse the list from the start (lowest address) block until
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183 one of adequate size is found. */
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184 pxPreviousBlock = &xStart;
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185 pxBlock = xStart.pxNextFreeBlock;
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186 while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock != NULL ) )
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188 pxPreviousBlock = pxBlock;
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189 pxBlock = pxBlock->pxNextFreeBlock;
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192 /* If the end marker was reached then a block of adequate size
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194 if( pxBlock != pxEnd )
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196 /* Return the memory space pointed to - jumping over the
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197 xBlockLink structure at its start. */
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198 pvReturn = ( void * ) ( ( ( unsigned char * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );
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200 /* This block is being returned for use so must be taken out
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201 of the list of free blocks. */
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202 pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;
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204 /* If the block is larger than required it can be split into
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206 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
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208 /* This block is to be split into two. Create a new
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209 block following the number of bytes requested. The void
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210 cast is used to prevent byte alignment warnings from the
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212 pxNewBlockLink = ( void * ) ( ( ( unsigned char * ) pxBlock ) + xWantedSize );
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214 /* Calculate the sizes of two blocks split from the
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216 pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
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217 pxBlock->xBlockSize = xWantedSize;
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219 /* Insert the new block into the list of free blocks. */
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220 prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
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223 xFreeBytesRemaining -= pxBlock->xBlockSize;
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225 /* The block is being returned - it is allocated and owned
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226 by the application and has no "next" block. */
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227 pxBlock->xBlockSize |= xBlockAllocatedBit;
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228 pxBlock->pxNextFreeBlock = NULL;
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233 traceMALLOC( pvReturn, xWantedSize );
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237 #if( configUSE_MALLOC_FAILED_HOOK == 1 )
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239 if( pvReturn == NULL )
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241 extern void vApplicationMallocFailedHook( void );
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242 vApplicationMallocFailedHook();
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249 /*-----------------------------------------------------------*/
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251 void vPortFree( void *pv )
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253 unsigned char *puc = ( unsigned char * ) pv;
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254 xBlockLink *pxLink;
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258 /* The memory being freed will have an xBlockLink structure immediately
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260 puc -= heapSTRUCT_SIZE;
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262 /* This casting is to keep the compiler from issuing warnings. */
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263 pxLink = ( void * ) puc;
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265 /* Check the block is actually allocated. */
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266 configASSERT( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 );
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267 configASSERT( pxLink->pxNextFreeBlock == NULL );
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269 if( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 )
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271 if( pxLink->pxNextFreeBlock == NULL )
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273 /* The block is being returned to the heap - it is no longer
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275 pxLink->xBlockSize &= ~xBlockAllocatedBit;
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279 /* Add this block to the list of free blocks. */
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280 xFreeBytesRemaining += pxLink->xBlockSize;
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281 prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );
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282 traceFREE( pv, pxLink->xBlockSize );
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289 /*-----------------------------------------------------------*/
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291 size_t xPortGetFreeHeapSize( void )
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293 return xFreeBytesRemaining;
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295 /*-----------------------------------------------------------*/
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297 void vPortInitialiseBlocks( void )
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299 /* This just exists to keep the linker quiet. */
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301 /*-----------------------------------------------------------*/
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303 static void prvHeapInit( void )
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305 xBlockLink *pxFirstFreeBlock;
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306 unsigned char *pucHeapEnd, *pucAlignedHeap;
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308 /* Ensure the heap starts on a correctly aligned boundary. */
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309 pucAlignedHeap = ( unsigned char * ) ( ( ( portPOINTER_SIZE_TYPE ) &ucHeap[ portBYTE_ALIGNMENT ] ) & ( ( portPOINTER_SIZE_TYPE ) ~portBYTE_ALIGNMENT_MASK ) );
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311 /* xStart is used to hold a pointer to the first item in the list of free
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312 blocks. The void cast is used to prevent compiler warnings. */
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313 xStart.pxNextFreeBlock = ( void * ) pucAlignedHeap;
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314 xStart.xBlockSize = ( size_t ) 0;
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316 /* pxEnd is used to mark the end of the list of free blocks and is inserted
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317 at the end of the heap space. */
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318 pucHeapEnd = pucAlignedHeap + xTotalHeapSize;
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319 pucHeapEnd -= heapSTRUCT_SIZE;
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320 pxEnd = ( void * ) pucHeapEnd;
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321 configASSERT( ( ( ( unsigned long ) pxEnd ) & ( ( unsigned long ) portBYTE_ALIGNMENT_MASK ) ) == 0UL );
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322 pxEnd->xBlockSize = 0;
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323 pxEnd->pxNextFreeBlock = NULL;
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325 /* To start with there is a single free block that is sized to take up the
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326 entire heap space, minus the space taken by pxEnd. */
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327 pxFirstFreeBlock = ( void * ) pucAlignedHeap;
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328 pxFirstFreeBlock->xBlockSize = xTotalHeapSize - heapSTRUCT_SIZE;
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329 pxFirstFreeBlock->pxNextFreeBlock = pxEnd;
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331 /* The heap now contains pxEnd. */
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332 xFreeBytesRemaining -= heapSTRUCT_SIZE;
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334 /* Work out the position of the top bit in a size_t variable. */
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335 xBlockAllocatedBit = ( ( size_t ) 1 ) << ( ( sizeof( size_t ) * heapBITS_PER_BYTE ) - 1 );
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337 /*-----------------------------------------------------------*/
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339 static void prvInsertBlockIntoFreeList( xBlockLink *pxBlockToInsert )
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341 xBlockLink *pxIterator;
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342 unsigned char *puc;
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344 /* Iterate through the list until a block is found that has a higher address
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345 than the block being inserted. */
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346 for( pxIterator = &xStart; pxIterator->pxNextFreeBlock < pxBlockToInsert; pxIterator = pxIterator->pxNextFreeBlock )
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348 /* Nothing to do here, just iterate to the right position. */
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351 /* Do the block being inserted, and the block it is being inserted after
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352 make a contiguous block of memory? */
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353 puc = ( unsigned char * ) pxIterator;
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354 if( ( puc + pxIterator->xBlockSize ) == ( unsigned char * ) pxBlockToInsert )
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356 pxIterator->xBlockSize += pxBlockToInsert->xBlockSize;
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357 pxBlockToInsert = pxIterator;
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360 /* Do the block being inserted, and the block it is being inserted before
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361 make a contiguous block of memory? */
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362 puc = ( unsigned char * ) pxBlockToInsert;
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363 if( ( puc + pxBlockToInsert->xBlockSize ) == ( unsigned char * ) pxIterator->pxNextFreeBlock )
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365 if( pxIterator->pxNextFreeBlock != pxEnd )
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367 /* Form one big block from the two blocks. */
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368 pxBlockToInsert->xBlockSize += pxIterator->pxNextFreeBlock->xBlockSize;
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369 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock->pxNextFreeBlock;
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373 pxBlockToInsert->pxNextFreeBlock = pxEnd;
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378 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;
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381 /* If the block being inserted plugged a gab, so was merged with the block
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382 before and the block after, then it's pxNextFreeBlock pointer will have
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383 already been set, and should not be set here as that would make it point
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385 if( pxIterator != pxBlockToInsert )
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387 pxIterator->pxNextFreeBlock = pxBlockToInsert;
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