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jeremybenn |
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). Thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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***NOTE*** The exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*
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* A sample implementation of pvPortMalloc() and vPortFree() that permits
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* allocated blocks to be freed, but does not combine adjacent free blocks
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* into a single larger block.
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*
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* See heap_1.c and heap_3.c for alternative implementations, and the memory
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* management pages of http://www.FreeRTOS.org for more information.
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*/
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#include <stdlib.h>
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/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
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all the API functions to use the MPU wrappers. That should only be done when
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task.h is included from an application file. */
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#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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#include "FreeRTOS.h"
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#include "task.h"
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#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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/* Allocate the memory for the heap. The struct is used to force byte
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alignment without using any non-portable code. */
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static union xRTOS_HEAP
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{
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#if portBYTE_ALIGNMENT == 8
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volatile portDOUBLE dDummy;
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#else
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volatile unsigned long ulDummy;
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#endif
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unsigned char ucHeap[ configTOTAL_HEAP_SIZE ];
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} xHeap;
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/* Define the linked list structure. This is used to link free blocks in order
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of their size. */
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typedef struct A_BLOCK_LINK
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{
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struct A_BLOCK_LINK *pxNextFreeBlock; /*<< The next free block in the list. */
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size_t xBlockSize; /*<< The size of the free block. */
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} xBlockLink;
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static const unsigned short heapSTRUCT_SIZE = ( sizeof( xBlockLink ) + portBYTE_ALIGNMENT - ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );
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#define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )
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/* Create a couple of list links to mark the start and end of the list. */
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static xBlockLink xStart, xEnd;
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/* Keeps track of the number of free bytes remaining, but says nothing about
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fragmentation. */
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static size_t xFreeBytesRemaining = configTOTAL_HEAP_SIZE;
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/* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */
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/*
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* Insert a block into the list of free blocks - which is ordered by size of
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* the block. Small blocks at the start of the list and large blocks at the end
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* of the list.
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*/
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#define prvInsertBlockIntoFreeList( pxBlockToInsert ) \
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{ \
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xBlockLink *pxIterator; \
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size_t xBlockSize; \
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\
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xBlockSize = pxBlockToInsert->xBlockSize; \
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\
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/* Iterate through the list until a block is found that has a larger size */ \
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/* than the block we are inserting. */ \
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for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \
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{ \
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/* There is nothing to do here - just iterate to the correct position. */ \
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} \
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\
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/* Update the list to include the block being inserted in the correct */ \
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/* position. */ \
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pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock; \
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pxIterator->pxNextFreeBlock = pxBlockToInsert; \
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}
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/*-----------------------------------------------------------*/
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#define prvHeapInit() \
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{ \
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xBlockLink *pxFirstFreeBlock; \
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\
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/* xStart is used to hold a pointer to the first item in the list of free */ \
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/* blocks. The void cast is used to prevent compiler warnings. */ \
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xStart.pxNextFreeBlock = ( void * ) xHeap.ucHeap; \
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xStart.xBlockSize = ( size_t ) 0; \
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\
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/* xEnd is used to mark the end of the list of free blocks. */ \
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xEnd.xBlockSize = configTOTAL_HEAP_SIZE; \
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xEnd.pxNextFreeBlock = NULL; \
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\
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/* To start with there is a single free block that is sized to take up the \
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entire heap space. */ \
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pxFirstFreeBlock = ( void * ) xHeap.ucHeap; \
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pxFirstFreeBlock->xBlockSize = configTOTAL_HEAP_SIZE; \
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pxFirstFreeBlock->pxNextFreeBlock = &xEnd; \
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}
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/*-----------------------------------------------------------*/
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void *pvPortMalloc( size_t xWantedSize )
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{
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xBlockLink *pxBlock, *pxPreviousBlock, *pxNewBlockLink;
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static portBASE_TYPE xHeapHasBeenInitialised = pdFALSE;
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void *pvReturn = NULL;
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vTaskSuspendAll();
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{
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/* If this is the first call to malloc then the heap will require
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initialisation to setup the list of free blocks. */
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if( xHeapHasBeenInitialised == pdFALSE )
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{
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prvHeapInit();
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xHeapHasBeenInitialised = pdTRUE;
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}
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/* The wanted size is increased so it can contain a xBlockLink
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structure in addition to the requested amount of bytes. */
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if( xWantedSize > 0 )
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{
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xWantedSize += heapSTRUCT_SIZE;
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/* Ensure that blocks are always aligned to the required number of bytes. */
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if( xWantedSize & portBYTE_ALIGNMENT_MASK )
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{
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/* Byte alignment required. */
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xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
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}
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}
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if( ( xWantedSize > 0 ) && ( xWantedSize < configTOTAL_HEAP_SIZE ) )
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{
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/* Blocks are stored in byte order - traverse the list from the start
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(smallest) block until one of adequate size is found. */
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pxPreviousBlock = &xStart;
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pxBlock = xStart.pxNextFreeBlock;
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while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock ) )
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{
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pxPreviousBlock = pxBlock;
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pxBlock = pxBlock->pxNextFreeBlock;
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}
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/* If we found the end marker then a block of adequate size was not found. */
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if( pxBlock != &xEnd )
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{
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/* Return the memory space - jumping over the xBlockLink structure
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at its start. */
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pvReturn = ( void * ) ( ( ( unsigned char * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );
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/* This block is being returned for use so must be taken our of the
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list of free blocks. */
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pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;
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/* If the block is larger than required it can be split into two. */
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if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
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{
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/* This block is to be split into two. Create a new block
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following the number of bytes requested. The void cast is
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used to prevent byte alignment warnings from the compiler. */
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pxNewBlockLink = ( void * ) ( ( ( unsigned char * ) pxBlock ) + xWantedSize );
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/* Calculate the sizes of two blocks split from the single
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block. */
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pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
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pxBlock->xBlockSize = xWantedSize;
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/* Insert the new block into the list of free blocks. */
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prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
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}
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xFreeBytesRemaining -= pxBlock->xBlockSize;
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}
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}
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}
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xTaskResumeAll();
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#if( configUSE_MALLOC_FAILED_HOOK == 1 )
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{
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if( pvReturn == NULL )
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{
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extern void vApplicationMallocFailedHook( void );
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vApplicationMallocFailedHook();
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}
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}
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#endif
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return pvReturn;
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}
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/*-----------------------------------------------------------*/
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void vPortFree( void *pv )
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{
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unsigned char *puc = ( unsigned char * ) pv;
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xBlockLink *pxLink;
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if( pv )
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{
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/* The memory being freed will have an xBlockLink structure immediately
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before it. */
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puc -= heapSTRUCT_SIZE;
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/* This casting is to keep the compiler from issuing warnings. */
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pxLink = ( void * ) puc;
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vTaskSuspendAll();
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{
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/* Add this block to the list of free blocks. */
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prvInsertBlockIntoFreeList( ( ( xBlockLink * ) pxLink ) );
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xFreeBytesRemaining += pxLink->xBlockSize;
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}
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xTaskResumeAll();
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}
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}
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/*-----------------------------------------------------------*/
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size_t xPortGetFreeHeapSize( void )
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{
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return xFreeBytesRemaining;
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}
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/*-----------------------------------------------------------*/
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void vPortInitialiseBlocks( void )
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{
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/* This just exists to keep the linker quiet. */
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}
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