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/*
FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
***************************************************************************
***************************************************************************
Please ensure to read the configuration and relevant port sections of the
online documentation.
http://www.FreeRTOS.org - Documentation, latest information, license and
contact details.
http://www.SafeRTOS.com - A version that is certified for use in safety
critical systems.
http://www.OpenRTOS.com - Commercial support, development, porting,
licensing and training services.
*/
/*
* A sample implementation of pvPortMalloc() and vPortFree() that permits
* allocated blocks to be freed, but does not combine adjacent free blocks
* into a single larger block.
*
* See heap_1.c and heap_3.c for alternative implementations, and the memory
* management pages of http://www.FreeRTOS.org for more information.
*/
#include <stdlib.h>
#include "FreeRTOS.h"
#include "task.h"
/* Setup the correct byte alignment mask for the defined byte alignment. */
#if portBYTE_ALIGNMENT == 8
#define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0007 )
#endif
#if portBYTE_ALIGNMENT == 4
#define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0003 )
#endif
#if portBYTE_ALIGNMENT == 2
#define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0001 )
#endif
#if portBYTE_ALIGNMENT == 1
#define heapBYTE_ALIGNMENT_MASK ( ( size_t ) 0x0000 )
#endif
#ifndef heapBYTE_ALIGNMENT_MASK
#error "Invalid portBYTE_ALIGNMENT definition"
#endif
/* Allocate the memory for the heap. The struct is used to force byte
alignment without using any non-portable code. */
static struct xRTOS_HEAP
{
unsigned portLONG ulDummy;
unsigned portCHAR ucHeap[ configTOTAL_HEAP_SIZE ];
} xHeap;
/* Define the linked list structure. This is used to link free blocks in order
of their size. */
typedef struct A_BLOCK_LINK
{
struct A_BLOCK_LINK *pxNextFreeBlock; /*<< The next free block in the list. */
size_t xBlockSize; /*<< The size of the free block. */
} xBlockLink;
static const unsigned portSHORT heapSTRUCT_SIZE = ( sizeof( xBlockLink ) + ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );
#define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )
/* Create a couple of list links to mark the start and end of the list. */
static xBlockLink xStart, xEnd;
/* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */
/*
* Insert a block into the list of free blocks - which is ordered by size of
* the block. Small blocks at the start of the list and large blocks at the end
* of the list.
*/
#define prvInsertBlockIntoFreeList( pxBlockToInsert ) \
{ \
xBlockLink *pxIterator; \
size_t xBlockSize; \
\
xBlockSize = pxBlockToInsert->xBlockSize; \
\
/* Iterate through the list until a block is found that has a larger size */ \
/* than the block we are inserting. */ \
for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \
{ \
/* There is nothing to do here - just iterate to the correct position. */ \
} \
\
/* Update the list to include the block being inserted in the correct */ \
/* position. */ \
pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock; \
pxIterator->pxNextFreeBlock = pxBlockToInsert; \
}
/*-----------------------------------------------------------*/
#define prvHeapInit() \
{ \
xBlockLink *pxFirstFreeBlock; \
\
/* xStart is used to hold a pointer to the first item in the list of free */ \
/* blocks. The void cast is used to prevent compiler warnings. */ \
xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap; \
xStart.xBlockSize = ( size_t ) 0; \
\
/* xEnd is used to mark the end of the list of free blocks. */ \
xEnd.xBlockSize = configTOTAL_HEAP_SIZE; \
xEnd.pxNextFreeBlock = NULL; \
\
/* To start with there is a single free block that is sized to take up the \
entire heap space. */ \
pxFirstFreeBlock = ( void * ) xHeap.ucHeap; \
pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE; \
pxFirstFreeBlock->pxNextFreeBlock = &xEnd; \
}
/*-----------------------------------------------------------*/
void *pvPortMalloc( size_t xWantedSize )
{
xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;
static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;
void *pvReturn = NULL;
vTaskSuspendAll();
{
/* If this is the first call to malloc then the heap will require
initialisation to setup the list of free blocks. */
if( xHeapHasBeenInitialised == pdFALSE )
{
prvHeapInit();
xHeapHasBeenInitialised = pdTRUE;
}
/* The wanted size is increased so it can contain a xBlockLink
structure in addition to the requested amount of bytes. */
if( xWantedSize > 0 )
{
xWantedSize += heapSTRUCT_SIZE;
/* Ensure that blocks are always aligned to the required number of bytes. */
if( xWantedSize & heapBYTE_ALIGNMENT_MASK )
{
/* Byte alignment required. */
xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & heapBYTE_ALIGNMENT_MASK ) );
}
}
if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )
{
/* Blocks are stored in byte order - traverse the list from the start
(smallest) block until one of adequate size is found. */
pxPreviousBlock = &xStart;
pxBlock = xStart.pxNextFreeBlock;
while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )
{
pxPreviousBlock = pxBlock;
pxBlock = pxBlock->pxNextFreeBlock;
}
/* If we found the end marker then a block of adequate size was not found. */
if( pxBlock != &xEnd )
{
/* Return the memory space - jumping over the xBlockLink structure
at its start. */
pvReturn = ( void * ) ( ( ( unsigned portCHAR * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );
/* This block is being returned for use so must be taken our of the
list of free blocks. */
pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;
/* If the block is larger than required it can be split into two. */
if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
{
/* This block is to be split into two. Create a new block
following the number of bytes requested. The void cast is
used to prevent byte alignment warnings from the compiler. */
pxNewBlockLink = ( void * ) ( ( ( unsigned portCHAR * ) pxBlock ) + xWantedSize );
/* Calculate the sizes of two blocks split from the single
block. */
pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
pxBlock->xBlockSize = xWantedSize;
/* Insert the new block into the list of free blocks. */
prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
}
}
}
}
xTaskResumeAll();
return pvReturn;
}
/*-----------------------------------------------------------*/
void vPortFree( void *pv )
{
unsigned portCHAR *puc = ( unsigned portCHAR * ) pv;
xBlockLink *pxLink;
if( pv )
{
/* The memory being freed will have an xBlockLink structure immediately
before it. */
puc -= heapSTRUCT_SIZE;
/* This casting is to keep the compiler from issuing warnings. */
pxLink = ( void * ) puc;
vTaskSuspendAll();
{
/* Add this block to the list of free blocks. */
prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );
}
xTaskResumeAll();
}
}
/*-----------------------------------------------------------*/
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