2 FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 This file is part of the FreeRTOS distribution.
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6 FreeRTOS is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License (version 2) as published by the
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8 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 without being obliged to provide the
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11 source code for proprietary components outside of the FreeRTOS kernel.
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12 Alternative commercial license and support terms are also available upon
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13 request. See the licensing section of http://www.FreeRTOS.org for full
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16 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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18 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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21 You should have received a copy of the GNU General Public License along
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22 with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
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23 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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26 ***************************************************************************
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28 * The FreeRTOS eBook and reference manual are available to purchase for a *
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29 * small fee. Help yourself get started quickly while also helping the *
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30 * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details *
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32 ***************************************************************************
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36 Please ensure to read the configuration and relevant port sections of the
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37 online documentation.
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39 http://www.FreeRTOS.org - Documentation, latest information, license and
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42 http://www.SafeRTOS.com - A version that is certified for use in safety
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45 http://www.OpenRTOS.com - Commercial support, development, porting,
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46 licensing and training services.
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50 * A sample implementation of pvPortMalloc() and vPortFree() that permits
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51 * allocated blocks to be freed, but does not combine adjacent free blocks
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52 * into a single larger block.
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54 * See heap_1.c and heap_3.c for alternative implementations, and the memory
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55 * management pages of http://www.FreeRTOS.org for more information.
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59 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
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60 all the API functions to use the MPU wrappers. That should only be done when
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61 task.h is included from an application file. */
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62 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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64 #include "FreeRTOS.h"
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67 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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69 /* Allocate the memory for the heap. The struct is used to force byte
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70 alignment without using any non-portable code. */
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71 static union xRTOS_HEAP
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73 #if portBYTE_ALIGNMENT == 8
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74 volatile portDOUBLE dDummy;
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76 volatile unsigned long ulDummy;
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78 unsigned char ucHeap[ configTOTAL_HEAP_SIZE ];
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81 /* Define the linked list structure. This is used to link free blocks in order
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83 typedef struct A_BLOCK_LINK
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85 struct A_BLOCK_LINK *pxNextFreeBlock; /*<< The next free block in the list. */
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86 size_t xBlockSize; /*<< The size of the free block. */
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90 static const unsigned short heapSTRUCT_SIZE = ( sizeof( xBlockLink ) + portBYTE_ALIGNMENT - ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );
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91 #define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )
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93 /* Create a couple of list links to mark the start and end of the list. */
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94 static xBlockLink xStart, xEnd;
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96 /* Keeps track of the number of free bytes remaining, but says nothing about
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98 static size_t xFreeBytesRemaining;
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100 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */
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103 * Insert a block into the list of free blocks - which is ordered by size of
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104 * the block. Small blocks at the start of the list and large blocks at the end
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107 #define prvInsertBlockIntoFreeList( pxBlockToInsert ) \
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109 xBlockLink *pxIterator; \
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110 size_t xBlockSize; \
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112 xBlockSize = pxBlockToInsert->xBlockSize; \
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114 /* Iterate through the list until a block is found that has a larger size */ \
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115 /* than the block we are inserting. */ \
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116 for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \
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118 /* There is nothing to do here - just iterate to the correct position. */ \
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121 /* Update the list to include the block being inserted in the correct */ \
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123 pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock; \
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124 pxIterator->pxNextFreeBlock = pxBlockToInsert; \
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126 /*-----------------------------------------------------------*/
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128 #define prvHeapInit() \
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130 xBlockLink *pxFirstFreeBlock; \
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132 /* xStart is used to hold a pointer to the first item in the list of free */ \
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133 /* blocks. The void cast is used to prevent compiler warnings. */ \
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134 xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap; \
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135 xStart.xBlockSize = ( size_t ) 0; \
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137 /* xEnd is used to mark the end of the list of free blocks. */ \
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138 xEnd.xBlockSize = configTOTAL_HEAP_SIZE; \
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139 xEnd.pxNextFreeBlock = NULL; \
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141 /* To start with there is a single free block that is sized to take up the \
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142 entire heap space. */ \
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143 pxFirstFreeBlock = ( void * ) xHeap.ucHeap; \
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144 pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE; \
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145 pxFirstFreeBlock->pxNextFreeBlock = &xEnd; \
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147 xFreeBytesRemaining = configTOTAL_HEAP_SIZE; \
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149 /*-----------------------------------------------------------*/
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151 void *pvPortMalloc( size_t xWantedSize )
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153 xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;
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154 static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;
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155 void *pvReturn = NULL;
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159 /* If this is the first call to malloc then the heap will require
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160 initialisation to setup the list of free blocks. */
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161 if( xHeapHasBeenInitialised == pdFALSE )
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164 xHeapHasBeenInitialised = pdTRUE;
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167 /* The wanted size is increased so it can contain a xBlockLink
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168 structure in addition to the requested amount of bytes. */
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169 if( xWantedSize > 0 )
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171 xWantedSize += heapSTRUCT_SIZE;
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173 /* Ensure that blocks are always aligned to the required number of bytes. */
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174 if( xWantedSize & portBYTE_ALIGNMENT_MASK )
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176 /* Byte alignment required. */
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177 xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
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181 if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )
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183 /* Blocks are stored in byte order - traverse the list from the start
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184 (smallest) block until one of adequate size is found. */
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185 pxPreviousBlock = &xStart;
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186 pxBlock = xStart.pxNextFreeBlock;
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187 while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )
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189 pxPreviousBlock = pxBlock;
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190 pxBlock = pxBlock->pxNextFreeBlock;
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193 /* If we found the end marker then a block of adequate size was not found. */
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194 if( pxBlock != &xEnd )
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196 /* Return the memory space - jumping over the xBlockLink structure
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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 our of the
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201 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 two. */
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205 if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
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207 /* This block is to be split into two. Create a new block
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208 following the number of bytes requested. The void cast is
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209 used to prevent byte alignment warnings from the compiler. */
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210 pxNewBlockLink = ( void * ) ( ( ( unsigned char * ) pxBlock ) + xWantedSize );
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212 /* Calculate the sizes of two blocks split from the single
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214 pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
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215 pxBlock->xBlockSize = xWantedSize;
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217 /* Insert the new block into the list of free blocks. */
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218 prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
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221 xFreeBytesRemaining -= xWantedSize;
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227 #if( configUSE_MALLOC_FAILED_HOOK == 1 )
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229 if( pvReturn == NULL )
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231 extern void vApplicationMallocFailedHook( void );
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232 vApplicationMallocFailedHook();
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239 /*-----------------------------------------------------------*/
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241 void vPortFree( void *pv )
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243 unsigned char *puc = ( unsigned char * ) pv;
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244 xBlockLink *pxLink;
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248 /* The memory being freed will have an xBlockLink structure immediately
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250 puc -= heapSTRUCT_SIZE;
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252 /* This casting is to keep the compiler from issuing warnings. */
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253 pxLink = ( void * ) puc;
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257 /* Add this block to the list of free blocks. */
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258 prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );
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259 xFreeBytesRemaining += pxLink->xBlockSize;
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264 /*-----------------------------------------------------------*/
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266 size_t xPortGetFreeHeapSize( void )
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268 return xFreeBytesRemaining;
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270 /*-----------------------------------------------------------*/
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272 void vPortInitialiseBlocks( void )
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274 /* This just exists to keep the linker quiet. */
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