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   1 /*
   2         FreeRTOS.org V4.3.1 - Copyright (C) 2003-2007 Richard Barry.
   3
   4         This file is part of the FreeRTOS.org distribution.
   5
   6         FreeRTOS.org is free software; you can redistribute it and/or modify
   7         it under the terms of the GNU General Public License as published by
   8         the Free Software Foundation; either version 2 of the License, or
   9         (at your option) any later version.
  10
  11         FreeRTOS.org is distributed in the hope that it will be useful,
  12         but WITHOUT ANY WARRANTY; without even the implied warranty of
  13         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14         GNU General Public License for more details.
  15
  16         You should have received a copy of the GNU General Public License
  17         along with FreeRTOS.org; if not, write to the Free Software
  18         Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19
  20         A special exception to the GPL can be applied should you wish to distribute
  21         a combined work that includes FreeRTOS.org, without being obliged to provide
  22         the source code for any proprietary components.  See the licensing section
  23         of http://www.FreeRTOS.org for full details of how and when the exception
  24         can be applied.
  25
  26         ***************************************************************************
  27         See http://www.FreeRTOS.org for documentation, latest information, license
  28         and contact details.  Please ensure to read the configuration and relevant
  29         port sections of the online documentation.
  30
  31         Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
  32         with commercial development and support options.
  33         ***************************************************************************
  34 */
  35
  36 /*
  37  * A sample implementation of pvPortMalloc() and vPortFree() that permits
  38  * allocated blocks to be freed, but does not combine adjacent free blocks
  39  * into a single larger block.
  40  *
  41  * See heap_1.c and heap_3.c for alternative implementations, and the memory
  42  * management pages of http://www.FreeRTOS.org for more information.
  43  */
  44 #include <stdlib.h>
  45
  46 #include "FreeRTOS.h"
  47 #include "task.h"
  48
  49 /* Setup the correct byte alignment mask for the defined byte alignment. */
  50
  51 #if portBYTE_ALIGNMENT == 8
  52         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0007 )
  53 #endif
  54
  55 #if portBYTE_ALIGNMENT == 4
  56         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0003 )
  57 #endif
  58
  59 #if portBYTE_ALIGNMENT == 2
  60         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0001 )
  61 #endif
  62
  63 #if portBYTE_ALIGNMENT == 1
  64         #define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0000 )
  65 #endif
  66
  67 #ifndef heapBYTE_ALIGNMENT_MASK
  68         #error "Invalid portBYTE_ALIGNMENT definition"
  69 #endif
  70
  71 /* Allocate the memory for the heap.  The struct is used to force byte
  72 alignment without using any non-portable code. */
  73 static struct xRTOS_HEAP
  74 {
  75         unsigned portLONG ulDummy;
  76         unsigned portCHAR ucHeap[ configTOTAL_HEAP_SIZE ];
  77 } xHeap;
  78
  79 /* Define the linked list structure.  This is used to link free blocks in order
  80 of their size. */
  81 typedef struct A_BLOCK_LINK
  82 {
  83         struct A_BLOCK_LINK *pxNextFreeBlock;   /*<< The next free block in the list. */
  84         size_t xBlockSize;                                              /*<< The size of the free block. */
  85 } xBlockLink;
  86
  87
  88 static const unsigned portSHORT  heapSTRUCT_SIZE        = ( sizeof( xBlockLink ) + ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );
  89 #define heapMINIMUM_BLOCK_SIZE  ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )
  90
  91 /* Create a couple of list links to mark the start and end of the list. */
  92 static xBlockLink xStart, xEnd;
  93
  94 /* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */
  95
  96 /*
  97  * Insert a block into the list of free blocks - which is ordered by size of
  98  * the block.  Small blocks at the start of the list and large blocks at the end
  99  * of the list.
 100  */
 101 #define prvInsertBlockIntoFreeList( pxBlockToInsert )                                                           \
 102 {                                                                                                                                                                       \
 103 xBlockLink *pxIterator;                                                                                                                         \
 104 size_t xBlockSize;                                                                                                                                      \
 105                                                                                                                                                                         \
 106         xBlockSize = pxBlockToInsert->xBlockSize;                                                                               \
 107                                                                                                                                                                         \
 108         /* Iterate through the list until a block is found that has a larger size */    \
 109         /* than the block we are inserting. */                                                                                  \
 110         for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock )     \
 111         {                                                                                                                                                               \
 112                 /* There is nothing to do here - just iterate to the correct position. */       \
 113         }                                                                                                                                                               \
 114                                                                                                                                                                         \
 115         /* Update the list to include the block being inserted in the correct */                \
 116         /* position. */                                                                                                                                 \
 117         pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;                                 \
 118         pxIterator->pxNextFreeBlock = pxBlockToInsert;                                                                  \
 119 }
 120 /*-----------------------------------------------------------*/
 121
 122 #define prvHeapInit()                                                                                                                           \
 123 {                                                                                                                                                                       \
 124 xBlockLink *pxFirstFreeBlock;                                                                                                           \
 125                                                                                                                                                                         \
 126         /* xStart is used to hold a pointer to the first item in the list of free */    \
 127         /* blocks.  The void cast is used to prevent compiler warnings. */                              \
 128         xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap;                                                               \
 129         xStart.xBlockSize = ( size_t ) 0;                                                                                               \
 130                                                                                                                                                                         \
 131         /* xEnd is used to mark the end of the list of free blocks. */                                  \
 132         xEnd.xBlockSize = configTOTAL_HEAP_SIZE;                                                                                \
 133         xEnd.pxNextFreeBlock = NULL;                                                                                                    \
 134                                                                                                                                                                         \
 135         /* To start with there is a single free block that is sized to take up the              \
 136         entire heap space. */                                                                                                                   \
 137         pxFirstFreeBlock = ( void * ) xHeap.ucHeap;                                                                             \
 138         pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE;                                                   \
 139         pxFirstFreeBlock->pxNextFreeBlock = &xEnd;                                                                              \
 140 }
 141 /*-----------------------------------------------------------*/
 142
 143 #if ( INCLUDE_vPortUsedMem == 1 )
 144
 145 void vPortUsedMem(int *bytesFree, int *bytesUsed, int *blocksFree)
 146 {
 147   xBlockLink *pxBlock = &xStart;
 148
 149   *bytesFree = 0;
 150   *bytesUsed = 0;
 151   *blocksFree = 0;
 152
 153   vTaskSuspendAll();
 154
 155   while ((pxBlock) && (pxBlock != &xEnd))
 156   {
 157     *bytesFree += pxBlock->xBlockSize;
 158     pxBlock = pxBlock->pxNextFreeBlock;
 159     ++*blocksFree;
 160   }
 161
 162   xTaskResumeAll();
 163
 164   *bytesUsed = configTOTAL_HEAP_SIZE - *bytesFree;
 165 }
 166
 167 #endif
 168 /*-----------------------------------------------------------*/
 169
 170 void *pvPortMalloc( size_t xWantedSize )
 171 {
 172   xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;
 173   static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;
 174   void *pvReturn = NULL;
 175
 176   vTaskSuspendAll();
 177   {
 178     /* If this is the first call to malloc then the heap will require
 179        initialisation to setup the list of free blocks. */
 180     if( xHeapHasBeenInitialised == pdFALSE )
 181     {
 182       prvHeapInit();
 183       xHeapHasBeenInitialised = pdTRUE;
 184     }
 185
 186     /* The wanted size is increased so it can contain a xBlockLink
 187        structure in addition to the requested amount of bytes. */
 188     if( xWantedSize > 0 )
 189     {
 190       xWantedSize += heapSTRUCT_SIZE;
 191
 192       /* Ensure that blocks are always aligned to the required number of bytes. */
 193       if( xWantedSize & heapBYTE_ALIGNMENT_MASK )
 194       {
 195         /* Byte alignment required. */
 196         xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & heapBYTE_ALIGNMENT_MASK ) );
 197       }
 198     }
 199
 200     if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )
 201     {
 202       /* Blocks are stored in byte order - traverse the list from the start
 203          (smallest) block until one of adequate size is found. */
 204       pxPreviousBlock = &xStart;
 205       pxBlock = xStart.pxNextFreeBlock;
 206       while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )
 207       {
 208         pxPreviousBlock = pxBlock;
 209         pxBlock = pxBlock->pxNextFreeBlock;
 210       }
 211
 212       /* If we found the end marker then a block of adequate size was not found. */
 213       if( pxBlock != &xEnd )
 214       {
 215         /* Return the memory space - jumping over the xBlockLink structure
 216            at its start. */
 217         pvReturn = ( void * ) ( ( ( unsigned portCHAR * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );
 218
 219         /* This block is being returned for use so must be taken our of the
 220            list of free blocks. */
 221         pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;
 222
 223         /* If the block is larger than required it can be split into two. */
 224         if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
 225         {
 226           /* This block is to be split into two.  Create a new block
 227              following the number of bytes requested. The void cast is
 228              used to prevent byte alignment warnings from the compiler. */
 229           pxNewBlockLink = ( void * ) ( ( ( unsigned portCHAR * ) pxBlock ) + xWantedSize );
 230
 231           /* Calculate the sizes of two blocks split from the single
 232              block. */
 233           pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
 234           pxBlock->xBlockSize = xWantedSize;
 235
 236           /* Insert the new block into the list of free blocks. */
 237           prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
 238         }
 239       }
 240     }
 241   }
 242   xTaskResumeAll();
 243
 244   return pvReturn;
 245 }
 246 /*-----------------------------------------------------------*/
 247
 248 void vPortFree( void *pv )
 249 {
 250 unsigned portCHAR *puc = ( unsigned portCHAR * ) pv;
 251 xBlockLink *pxLink;
 252
 253         if( pv )
 254         {
 255                 /* The memory being freed will have an xBlockLink structure immediately
 256                 before it. */
 257                 puc -= heapSTRUCT_SIZE;
 258
 259                 /* This casting is to keep the compiler from issuing warnings. */
 260                 pxLink = ( void * ) puc;
 261
 262                 vTaskSuspendAll();
 263                 {
 264                         /* Add this block to the list of free blocks. */
 265                         prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );
 266                 }
 267                 xTaskResumeAll();
 268         }
 269 }
 270 /*-----------------------------------------------------------*/
 271