heap_6.c

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*/

/*
 * A sample implementation of pvPortMalloc() and vPortFree() that combines
 * (coalescences) adjacent memory blocks as they are freed, and in so doing
 * limits memory fragmentation.
 *
 * See heap_1.c, heap_2.c and heap_3.c for alternative implementations, and the
 * memory management pages of http://www.FreeRTOS.org for more information.
 */
#include <stdlib.h>
void * memmove ( void * destination, const void * source, size_t num );

/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
all the API functions to use the MPU wrappers.  That should only be done when
task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

#include "FreeRTOS.h"
#include "task.h"

#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE

/* Block sizes must not get too small. */
#define heapMINIMUM_BLOCK_SIZE	( ( size_t ) ( heapSTRUCT_SIZE * 2 ) )

/* Assumes 8bit bytes! */
#define heapBITS_PER_BYTE		( ( size_t ) 8 )

/* A few bytes might be lost to byte aligning the heap start address. */
#define heapADJUSTED_HEAP_SIZE	( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )

#define HEAP_MAGIC 0xabcddcba
#define heapMAGIC_SIZE 4

/* Allocate the memory for the heap. */
#include "heap_regions.h"

typedef struct HeapRegion
{
	uint8_t *pucStartAddress; // << Start address of a block of memory that will be part of the heap.
	size_t xSizeInBytes;	 // << Size of the block of memory.
} HeapRegion_t;

/* Define the linked list structure.  This is used to link free blocks in order
of their memory address. */
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. */
} BlockLink_t;

/*-----------------------------------------------------------*/

/*
 * Inserts a block of memory that is being freed into the correct position in
 * the list of free memory blocks.  The block being freed will be merged with
 * the block in front it and/or the block behind it if the memory blocks are
 * adjacent to each other.
 */
static void prvInsertBlockIntoFreeList( BlockLink_t *pxBlockToInsert );

/*
 * Called automatically to setup the required heap structures the first time
 * pvPortMalloc() is called.
 */
static void prvHeapInit( void );

/*-----------------------------------------------------------*/

/* The size of the structure placed at the beginning of each allocated memory
block must by correctly byte aligned. */
static const uint16_t heapSTRUCT_SIZE	= ( ( sizeof ( BlockLink_t ) + ( portBYTE_ALIGNMENT - 1 ) ) & ~portBYTE_ALIGNMENT_MASK );

/* Ensure the pxEnd pointer will end up on the correct byte alignment. */
static const size_t xTotalHeapSize = ( ( size_t ) heapADJUSTED_HEAP_SIZE ) & ( ( size_t ) ~portBYTE_ALIGNMENT_MASK );

/* Create a couple of list links to mark the start and end of the list. */
static BlockLink_t xStart, *pxEnd = NULL;

/* Keeps track of the number of free bytes remaining, but says nothing about
fragmentation. */
static size_t xFreeBytesRemaining = ( ( size_t ) heapADJUSTED_HEAP_SIZE ) & ( ( size_t ) ~portBYTE_ALIGNMENT_MASK );
static size_t xMinimumEverFreeBytesRemaining = ( ( size_t ) heapADJUSTED_HEAP_SIZE ) & ( ( size_t ) ~portBYTE_ALIGNMENT_MASK );

/* Gets set to the top bit of an size_t type.  When this bit in the xBlockSize
member of an BlockLink_t structure is set then the block belongs to the
application.  When the bit is free the block is still part of the free heap
space. */
static size_t xBlockAllocatedBit = 0;

/*-----------------------------------------------------------*/
void pvPortHeapViz( char * c, int n ) {
	long i,blocksz = heapADJUSTED_HEAP_SIZE / (n-1);
	vTaskSuspendAll();
	BlockLink_t * pxBlock = xStart.pxNextFreeBlock;
	while(  ( pxBlock->pxNextFreeBlock != NULL ) )
	{
		for(i=(pxBlock-&xStart)/blocksz;i<(pxBlock-&xStart+pxBlock->xBlockSize)/blocksz;++i){
			c[i] = ' ';
		}
		pxBlock = pxBlock->pxNextFreeBlock;
	}
	( void ) xTaskResumeAll();
}

void *pvPortRealloc( void *pv, size_t xWantedSize )
{
uint8_t *puc = ( uint8_t * ) pv;
BlockLink_t *pxLink, *pxNewBlockLink;

	if( xWantedSize == 0 ) {
		vPortFree(pv);
		return NULL;
	}

	if( pv != NULL )
	{
		vTaskSuspendAll();

		/* The memory will have an BlockLink_t structure immediately
		before it. */
		puc -= heapSTRUCT_SIZE;

		/* This casting is to keep the compiler from issuing warnings. */
		pxLink = ( void * ) puc;

		/* Check the block is actually allocated. */
		#define B(x) (x & ~xBlockAllocatedBit)
		configASSERT( *(int*)(puc+B(pxLink->xBlockSize)-4) == HEAP_MAGIC );
		configASSERT( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 );
		configASSERT( pxLink->pxNextFreeBlock == NULL );

		xWantedSize += heapSTRUCT_SIZE;
		xWantedSize += heapMAGIC_SIZE;

		/* Ensure that blocks are always aligned to the required number
		of bytes. */
		if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )
		{
			/* Byte alignment required. */
			xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}

		if( xWantedSize == B(pxLink->xBlockSize) ) {
			( void ) xTaskResumeAll();
			return pv;
		} else if( xWantedSize < B(pxLink->xBlockSize) ) { //realloc'ing down (or maybe reallocing up but was given a really large block to start, consider tracking used size as well as block size)
			if(xWantedSize < heapMINIMUM_BLOCK_SIZE || B(pxLink->xBlockSize) - xWantedSize < heapMINIMUM_BLOCK_SIZE) {
				//don't change anything - the block is already too small and there's not enough space being freed to make a new block
				( void ) xTaskResumeAll();
				return pv;
			}

			size_t diff =  B(pxLink->xBlockSize) - xWantedSize;

			//split the block and insert the new one into the free list
			pxNewBlockLink = ( void * ) ( ( ( uint8_t * ) pxLink ) + xWantedSize );

			/* Calculate the sizes of two blocks split from the
			single block. */
			pxNewBlockLink->xBlockSize = diff;
			xFreeBytesRemaining += diff;
			pxLink->xBlockSize = xWantedSize|xBlockAllocatedBit;
			*(int*)(puc+xWantedSize-4) = HEAP_MAGIC;

			/* Insert the new block into the list of free blocks. */
			prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );

			traceFREE( pv, diff );
			( void ) xTaskResumeAll();
			return pv;
		} else {
			//make sure it's not too much...
			if( puc + xWantedSize > (uint8_t*)pxEnd ) {
				( void ) xTaskResumeAll();
				return NULL;
			}
			size_t original_size = B(pxLink->xBlockSize);
			size_t diff = xWantedSize - original_size;

			//increasing size...
			pxNewBlockLink = (BlockLink_t*)(puc+B(pxLink->xBlockSize));
			if( !(pxNewBlockLink->xBlockSize&xBlockAllocatedBit)
					&& xWantedSize<B(pxLink->xBlockSize)+B(pxNewBlockLink->xBlockSize) ) //see if we can grab the next block...
			{
				/*  Walk the free list to find the previous link so we can remove the next block from the list */
				BlockLink_t * pxPreviousBlock = &xStart;
				BlockLink_t * pxBlock = xStart.pxNextFreeBlock;
				BlockLink_t * pxDest = (BlockLink_t*)(puc+xWantedSize);

				while( ( pxBlock !=  pxNewBlockLink) && ( pxBlock->pxNextFreeBlock != NULL ) )
				{
					pxPreviousBlock = pxBlock;
					pxBlock = pxBlock->pxNextFreeBlock;
				}
				*pxDest = *pxNewBlockLink;
				pxDest->xBlockSize -= diff;
				pxPreviousBlock->pxNextFreeBlock = pxDest;
				pxLink->xBlockSize = xWantedSize|xBlockAllocatedBit;
				*(int*)(puc+xWantedSize-4) = HEAP_MAGIC;

				xFreeBytesRemaining -= diff;

				traceMALLOC( pv, diff );
				( void ) xTaskResumeAll();
				return pv;
			}
			//got to memmove... didn't find enough contiguous blocks
			{
				void * mem = pvPortMalloc(xWantedSize);
				if( mem ) {
					memmove(mem, pv, B(pxLink->xBlockSize) - heapSTRUCT_SIZE);
					vPortFree(pv);
					( void ) xTaskResumeAll();
					return mem;
				}
				( void ) xTaskResumeAll();
				return NULL;
			}
		}
	} else {
		return pvPortMalloc(xWantedSize);
	}
}

void *pvPortMalloc( size_t xWantedSize )
{
BlockLink_t *pxBlock, *pxPreviousBlock, *pxNewBlockLink;
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( pxEnd == NULL )
		{
			prvHeapInit();
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}

		/* Check the requested block size is not so large that the top bit is
		set.  The top bit of the block size member of the BlockLink_t structure
		is used to determine who owns the block - the application or the
		kernel, so it must be free. */
		if( ( xWantedSize & xBlockAllocatedBit ) == 0 )
		{
			/* The wanted size is increased so it can contain a BlockLink_t
			structure in addition to the requested amount of bytes. */
			if( xWantedSize > 0 )
			{
				xWantedSize += heapSTRUCT_SIZE;
				xWantedSize += heapMAGIC_SIZE;

				/* Ensure that blocks are always aligned to the required number
				of bytes. */
				if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )
				{
					/* Byte alignment required. */
					xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
				}
				else
				{
					mtCOVERAGE_TEST_MARKER();
				}
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}

			if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
			{
				/* Traverse the list from the start	(lowest address) block until
				one	of adequate size is found. */
				pxPreviousBlock = &xStart;
				pxBlock = xStart.pxNextFreeBlock;
				while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock != NULL ) )
				{
					pxPreviousBlock = pxBlock;
					pxBlock = pxBlock->pxNextFreeBlock;
				}

				/* If the end marker was reached then a block of adequate size
				was	not found. */
				if( pxBlock != pxEnd )
				{
					/* Return the memory space pointed to - jumping over the
					BlockLink_t structure at its start. */
					pvReturn = ( void * ) ( ( ( uint8_t * ) pxPreviousBlock->pxNextFreeBlock ) + heapSTRUCT_SIZE );

					/* This block is being returned for use so must be taken out
					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 * ) ( ( ( uint8_t * ) 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 ) );
					}
					else
					{
						mtCOVERAGE_TEST_MARKER();
					}

					xFreeBytesRemaining -= pxBlock->xBlockSize;

					if( xFreeBytesRemaining < xMinimumEverFreeBytesRemaining )
					{
						xMinimumEverFreeBytesRemaining = xFreeBytesRemaining;
					}
					else
					{
						mtCOVERAGE_TEST_MARKER();
					}

					/* The block is being returned - it is allocated and owned
					by the application and has no "next" block. */
					*(int*)(((char*)pxBlock)+pxBlock->xBlockSize-4) = HEAP_MAGIC;
					pxBlock->xBlockSize |= xBlockAllocatedBit;
					pxBlock->pxNextFreeBlock = NULL;
				}
				else
				{
					mtCOVERAGE_TEST_MARKER();
				}
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}

		traceMALLOC( pvReturn, xWantedSize );
	}
	( void ) xTaskResumeAll();

	#if( configUSE_MALLOC_FAILED_HOOK == 1 )
	{
		if( pvReturn == NULL )
		{
			extern void vApplicationMallocFailedHook( void );
			vApplicationMallocFailedHook();
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}
	}
	#endif

	return pvReturn;
}
/*-----------------------------------------------------------*/

void vPortFree( void *pv )
{
uint8_t *puc = ( uint8_t * ) pv;
BlockLink_t *pxLink;

	if( pv != NULL )
	{
		/* The memory being freed will have an BlockLink_t structure immediately
		before it. */
		puc -= heapSTRUCT_SIZE;

		/* This casting is to keep the compiler from issuing warnings. */
		pxLink = ( void * ) puc;

		/* Check the block is actually allocated. */
		configASSERT( *(int*)(puc+B(pxLink->xBlockSize)-4) == HEAP_MAGIC );
		configASSERT( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 );
		configASSERT( pxLink->pxNextFreeBlock == NULL );

		if( ( pxLink->xBlockSize & xBlockAllocatedBit ) != 0 )
		{
			if( pxLink->pxNextFreeBlock == NULL )
			{
				/* The block is being returned to the heap - it is no longer
				allocated. */
				pxLink->xBlockSize &= ~xBlockAllocatedBit;

				vTaskSuspendAll();
				{
					/* Add this block to the list of free blocks. */
					xFreeBytesRemaining += pxLink->xBlockSize;
					traceFREE( pv, pxLink->xBlockSize );
					prvInsertBlockIntoFreeList( ( ( BlockLink_t * ) pxLink ) );
				}
				( void ) xTaskResumeAll();
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}
	}
}
/*-----------------------------------------------------------*/

size_t xPortGetFreeHeapSize( void )
{
	return xFreeBytesRemaining;
}
/*-----------------------------------------------------------*/

size_t xPortGetMinimumEverFreeHeapSize( void )
{
	return xMinimumEverFreeBytesRemaining;
}
/*-----------------------------------------------------------*/

void vPortInitialiseBlocks( void )
{
	/* This just exists to keep the linker quiet. */
}
/*-----------------------------------------------------------*/

void vPortDefineHeapRegions( const HeapRegion_t * const pxHeapRegions )
{
BlockLink_t *pxFirstFreeBlockInRegion = NULL, *pxPreviousFreeBlock;
uint8_t *pucAlignedHeap;
size_t xTotalRegionSize, xTotalHeapSize = 0;
BaseType_t xDefinedRegions = 0;
size_t ulAddress;
const HeapRegion_t *pxHeapRegion;

	/* Can only call once! */
	configASSERT( pxEnd == NULL );

	pxHeapRegion = &( pxHeapRegions[ xDefinedRegions ] );

	while( pxHeapRegion->xSizeInBytes > 0 )
	{
		xTotalRegionSize = pxHeapRegion->xSizeInBytes;

		/* Ensure the heap region starts on a correctly aligned boundary. */
		ulAddress = ( size_t ) pxHeapRegion->pucStartAddress;
		if( ( ulAddress & portBYTE_ALIGNMENT_MASK ) != 0 )
		{
			ulAddress += ( portBYTE_ALIGNMENT - 1 );
			ulAddress &= ~portBYTE_ALIGNMENT_MASK;

			/* Adjust the size for the bytes lost to alignment. */
			xTotalRegionSize -= ulAddress - ( size_t ) pxHeapRegion->pucStartAddress;
		}

		pucAlignedHeap = ( uint8_t * ) (void*) ulAddress;

		/* Set xStart if it has not already been set. */
		if( xDefinedRegions == 0 )
		{
			/* 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 = ( BlockLink_t * ) pucAlignedHeap;
			xStart.xBlockSize = ( size_t ) 0;
		}
		else
		{
			/* Should only get here if one region has already been added to the
			heap. */
			configASSERT( pxEnd != NULL );

			/* Check blocks are passed in with increasing start addresses. */
			configASSERT( ulAddress > ( size_t ) pxEnd );
		}

		/* Remember the location of the end marker in the previous region, if
		any. */
		pxPreviousFreeBlock = pxEnd;

		/* pxEnd is used to mark the end of the list of free blocks and is
		inserted at the end of the region space. */
		ulAddress = ( ( size_t ) pucAlignedHeap ) + xTotalRegionSize;
		ulAddress -= heapSTRUCT_SIZE;
		ulAddress &= ~portBYTE_ALIGNMENT_MASK;
		pxEnd = ( BlockLink_t * ) ulAddress;
		pxEnd->xBlockSize = 0;
		pxEnd->pxNextFreeBlock = NULL;

		/* To start with there is a single free block in this region that is
		sized to take up the entire heap region minus the space taken by the
		free block structure. */
		pxFirstFreeBlockInRegion = ( BlockLink_t * ) pucAlignedHeap;
		pxFirstFreeBlockInRegion->xBlockSize = ulAddress - ( size_t ) pxFirstFreeBlockInRegion;
		pxFirstFreeBlockInRegion->pxNextFreeBlock = pxEnd;

		/* If this is not the first region that makes up the entire heap space
		then link the previous region to this region. */
		if( pxPreviousFreeBlock != NULL )
		{
			pxPreviousFreeBlock->pxNextFreeBlock = pxFirstFreeBlockInRegion;
		}

		xTotalHeapSize += pxFirstFreeBlockInRegion->xBlockSize;

		/* Move onto the next HeapRegion_t structure. */
		xDefinedRegions++;
		pxHeapRegion = &( pxHeapRegions[ xDefinedRegions ] );
	}

	xMinimumEverFreeBytesRemaining = xTotalHeapSize;
	xFreeBytesRemaining = xTotalHeapSize;

	/* Check something was actually defined before it is accessed. */
	configASSERT( xTotalHeapSize );

	/* Work out the position of the top bit in a size_t variable. */
	xBlockAllocatedBit = ( ( size_t ) 1 ) << ( ( sizeof( size_t ) * heapBITS_PER_BYTE ) - 1 );
}

static void prvHeapInit( void )
{
	HeapRegion_t xHeapRegions[NUM_HEAP_REGIONS+1];

	heap_regions_init(xHeapRegions);

	vPortDefineHeapRegions( xHeapRegions );
}
/*-----------------------------------------------------------*/

static void prvInsertBlockIntoFreeList( BlockLink_t *pxBlockToInsert )
{
BlockLink_t *pxIterator;
uint8_t *puc;

	/* Iterate through the list until a block is found that has a higher address
	than the block being inserted. */
	for( pxIterator = &xStart; pxIterator->pxNextFreeBlock < pxBlockToInsert; pxIterator = pxIterator->pxNextFreeBlock )
	{
		/* Nothing to do here, just iterate to the right position. */
	}

	/* Do the block being inserted, and the block it is being inserted after
	make a contiguous block of memory? */
	puc = ( uint8_t * ) pxIterator;
	if( ( puc + pxIterator->xBlockSize ) == ( uint8_t * ) pxBlockToInsert )
	{
		pxIterator->xBlockSize += pxBlockToInsert->xBlockSize;
		pxBlockToInsert = pxIterator;
	}
	else
	{
		mtCOVERAGE_TEST_MARKER();
	}

	/* Do the block being inserted, and the block it is being inserted before
	make a contiguous block of memory? */
	puc = ( uint8_t * ) pxBlockToInsert;
	if( ( puc + pxBlockToInsert->xBlockSize ) == ( uint8_t * ) pxIterator->pxNextFreeBlock )
	{
		if( pxIterator->pxNextFreeBlock != pxEnd )
		{
			/* Form one big block from the two blocks. */
			pxBlockToInsert->xBlockSize += pxIterator->pxNextFreeBlock->xBlockSize;
			pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock->pxNextFreeBlock;
		}
		else
		{
			pxBlockToInsert->pxNextFreeBlock = pxEnd;
		}
	}
	else
	{
		pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;
	}

	/* If the block being inserted plugged a gab, so was merged with the block
	before and the block after, then it's pxNextFreeBlock pointer will have
	already been set, and should not be set here as that would make it point
	to itself. */
	if( pxIterator != pxBlockToInsert )
	{
		pxIterator->pxNextFreeBlock = pxBlockToInsert;
	}
	else
	{
		mtCOVERAGE_TEST_MARKER();
	}
}