heap_1.c

00001 /*
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00003     All rights reserved
00004 
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00006 
00007     ***************************************************************************
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00019     ***************************************************************************
00020 
00021     This file is part of the FreeRTOS distribution.
00022 
00023     FreeRTOS is free software; you can redistribute it and/or modify it under
00024     the terms of the GNU General Public License (version 2) as published by the
00025     Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
00026 
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00039     ***************************************************************************
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00063     1 tab == 4 spaces!
00064 */
00065 
00066 
00067 /*
00068  * The simplest possible implementation of pvPortMalloc().  Note that this
00069  * implementation does NOT allow allocated memory to be freed again.
00070  *
00071  * See heap_2.c, heap_3.c and heap_4.c for alternative implementations, and the
00072  * memory management pages of http://www.FreeRTOS.org for more information.
00073  */
00074 #include <stdlib.h>
00075 
00076 /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
00077 all the API functions to use the MPU wrappers.  That should only be done when
00078 task.h is included from an application file. */
00079 #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
00080 
00081 #include "FreeRTOS.h"
00082 #include "task.h"
00083 
00084 #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
00085 
00086 /* A few bytes might be lost to byte aligning the heap start address. */
00087 #define configADJUSTED_HEAP_SIZE    ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )
00088 
00089 /* Allocate the memory for the heap. */
00090 static unsigned char ucHeap[ configTOTAL_HEAP_SIZE ];
00091 static size_t xNextFreeByte = ( size_t ) 0;
00092 
00093 /*-----------------------------------------------------------*/
00094 
00095 void *pvPortMalloc( size_t xWantedSize )
00096 {
00097 void *pvReturn = NULL;
00098 static unsigned char *pucAlignedHeap = NULL;
00099 
00100     /* Ensure that blocks are always aligned to the required number of bytes. */
00101     #if portBYTE_ALIGNMENT != 1
00102         if( xWantedSize & portBYTE_ALIGNMENT_MASK )
00103         {
00104             /* Byte alignment required. */
00105             xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
00106         }
00107     #endif
00108 
00109     vTaskSuspendAll();
00110     {
00111         if( pucAlignedHeap == NULL )
00112         {
00113             /* Ensure the heap starts on a correctly aligned boundary. */
00114             pucAlignedHeap = ( unsigned char * ) ( ( ( portPOINTER_SIZE_TYPE ) &ucHeap[ portBYTE_ALIGNMENT ] ) & ( ( portPOINTER_SIZE_TYPE ) ~portBYTE_ALIGNMENT_MASK ) );
00115         }
00116 
00117         /* Check there is enough room left for the allocation. */
00118         if( ( ( xNextFreeByte + xWantedSize ) < configADJUSTED_HEAP_SIZE ) &&
00119             ( ( xNextFreeByte + xWantedSize ) > xNextFreeByte ) )/* Check for overflow. */
00120         {
00121             /* Return the next free byte then increment the index past this
00122             block. */
00123             pvReturn = pucAlignedHeap + xNextFreeByte;
00124             xNextFreeByte += xWantedSize;
00125         }
00126 
00127         traceMALLOC( pvReturn, xWantedSize );
00128     }   
00129     xTaskResumeAll();
00130 
00131     #if( configUSE_MALLOC_FAILED_HOOK == 1 )
00132     {
00133         if( pvReturn == NULL )
00134         {
00135             extern void vApplicationMallocFailedHook( void );
00136             vApplicationMallocFailedHook();
00137         }
00138     }
00139     #endif
00140 
00141     return pvReturn;
00142 }
00143 /*-----------------------------------------------------------*/
00144 
00145 void vPortFree( void *pv )
00146 {
00147     /* Memory cannot be freed using this scheme.  See heap_2.c, heap_3.c and
00148     heap_4.c for alternative implementations, and the memory management pages of
00149     http://www.FreeRTOS.org for more information. */
00150     ( void ) pv;
00151 
00152     /* Force an assert as it is invalid to call this function. */
00153     configASSERT( pv == NULL );
00154 }
00155 /*-----------------------------------------------------------*/
00156 
00157 void vPortInitialiseBlocks( void )
00158 {
00159     /* Only required when static memory is not cleared. */
00160     xNextFreeByte = ( size_t ) 0;
00161 }
00162 /*-----------------------------------------------------------*/
00163 
00164 size_t xPortGetFreeHeapSize( void )
00165 {
00166     return ( configADJUSTED_HEAP_SIZE - xNextFreeByte );
00167 }
00168 
00169 
00170