portable/MemMang/heap_4.c - third_party/github/FreeRTOS/FreeRTOS-Kernel - Git at Google

 /*
  * FreeRTOS Kernel V10.3.1
  * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
  * this software and associated documentation files (the "Software"), to deal in
  * the Software without restriction, including without limitation the rights to
  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
  * the Software, and to permit persons to whom the Software is furnished to do so,
  * subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in all
  * copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
  * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
  * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  * http://www.FreeRTOS.org
  * http://aws.amazon.com/freertos
  *
  * 1 tab == 4 spaces!
  */

 /*
  * 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>

 /* 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

 #if( configSUPPORT_DYNAMIC_ALLOCATION == 0 )
 	#error This file must not be used if configSUPPORT_DYNAMIC_ALLOCATION is 0
 #endif

 /* Block sizes must not get too small. */
 #define heapMINIMUM_BLOCK_SIZE	( ( size_t ) ( xHeapStructSize << 1 ) )

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

 /* Allocate the memory for the heap. */
 #if( configAPPLICATION_ALLOCATED_HEAP == 1 )
 	/* The application writer has already defined the array used for the RTOS
 	heap - probably so it can be placed in a special segment or address. */
 	extern uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
 #else
 	static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
 #endif /* configAPPLICATION_ALLOCATED_HEAP */

 /* 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 size_t xHeapStructSize	= ( sizeof( BlockLink_t ) + ( ( size_t ) ( portBYTE_ALIGNMENT - 1 ) ) ) & ~( ( 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 calls to allocate and free memory as well as the
 number of free bytes remaining, but says nothing about fragmentation. */
 static size_t xFreeBytesRemaining = 0U;
 static size_t xMinimumEverFreeBytesRemaining = 0U;
 static size_t xNumberOfSuccessfulAllocations = 0;
 static size_t xNumberOfSuccessfulFrees = 0;

 /* 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 *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 += xHeapStructSize;

 				/* 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 ) );
 					configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 );
 				}
 				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 ) + xHeapStructSize );

 					/* 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 );
 						configASSERT( ( ( ( size_t ) pxNewBlockLink ) & portBYTE_ALIGNMENT_MASK ) == 0 );

 						/* 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. */
 					pxBlock->xBlockSize |= xBlockAllocatedBit;
 					pxBlock->pxNextFreeBlock = NULL;
 					xNumberOfSuccessfulAllocations++;
 				}
 				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

 	configASSERT( ( ( ( size_t ) pvReturn ) & ( size_t ) portBYTE_ALIGNMENT_MASK ) == 0 );
 	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 -= xHeapStructSize;

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

 		/* Check the block is actually allocated. */
 		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 ) );
 					xNumberOfSuccessfulFrees++;
 				}
 				( 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. */
 }
 /*-----------------------------------------------------------*/

 static void prvHeapInit( void )
 {
 BlockLink_t *pxFirstFreeBlock;
 uint8_t *pucAlignedHeap;
 size_t uxAddress;
 size_t xTotalHeapSize = configTOTAL_HEAP_SIZE;

 	/* Ensure the heap starts on a correctly aligned boundary. */
 	uxAddress = ( size_t ) ucHeap;

 	if( ( uxAddress & portBYTE_ALIGNMENT_MASK ) != 0 )
 	{
 		uxAddress += ( portBYTE_ALIGNMENT - 1 );
 		uxAddress &= ~( ( size_t ) portBYTE_ALIGNMENT_MASK );
 		xTotalHeapSize -= uxAddress - ( size_t ) ucHeap;
 	}

 	pucAlignedHeap = ( uint8_t * ) uxAddress;

 	/* 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 * ) pucAlignedHeap;
 	xStart.xBlockSize = ( size_t ) 0;

 	/* pxEnd is used to mark the end of the list of free blocks and is inserted
 	at the end of the heap space. */
 	uxAddress = ( ( size_t ) pucAlignedHeap ) + xTotalHeapSize;
 	uxAddress -= xHeapStructSize;
 	uxAddress &= ~( ( size_t ) portBYTE_ALIGNMENT_MASK );
 	pxEnd = ( void * ) uxAddress;
 	pxEnd->xBlockSize = 0;
 	pxEnd->pxNextFreeBlock = NULL;

 	/* To start with there is a single free block that is sized to take up the
 	entire heap space, minus the space taken by pxEnd. */
 	pxFirstFreeBlock = ( void * ) pucAlignedHeap;
 	pxFirstFreeBlock->xBlockSize = uxAddress - ( size_t ) pxFirstFreeBlock;
 	pxFirstFreeBlock->pxNextFreeBlock = pxEnd;

 	/* Only one block exists - and it covers the entire usable heap space. */
 	xMinimumEverFreeBytesRemaining = pxFirstFreeBlock->xBlockSize;
 	xFreeBytesRemaining = pxFirstFreeBlock->xBlockSize;

 	/* 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 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();
 	}
 }
 /*-----------------------------------------------------------*/

 void vPortGetHeapStats( HeapStats_t *pxHeapStats )
 {
 BlockLink_t *pxBlock;
 size_t xBlocks = 0, xMaxSize = 0, xMinSize = portMAX_DELAY; /* portMAX_DELAY used as a portable way of getting the maximum value. */

 	vTaskSuspendAll();
 	{
 		pxBlock = xStart.pxNextFreeBlock;

 		/* pxBlock will be NULL if the heap has not been initialised.  The heap
 		is initialised automatically when the first allocation is made. */
 		if( pxBlock != NULL )
 		{
 			do
 			{
 				/* Increment the number of blocks and record the largest block seen
 				so far. */
 				xBlocks++;

 				if( pxBlock->xBlockSize > xMaxSize )
 				{
 					xMaxSize = pxBlock->xBlockSize;
 				}

 				if( pxBlock->xBlockSize < xMinSize )
 				{
 					xMinSize = pxBlock->xBlockSize;
 				}

 				/* Move to the next block in the chain until the last block is
 				reached. */
 				pxBlock = pxBlock->pxNextFreeBlock;
 			} while( pxBlock != pxEnd );
 		}
 	}
 	xTaskResumeAll();

 	pxHeapStats->xSizeOfLargestFreeBlockInBytes = xMaxSize;
 	pxHeapStats->xSizeOfSmallestFreeBlockInBytes = xMinSize;
 	pxHeapStats->xNumberOfFreeBlocks = xBlocks;

 	taskENTER_CRITICAL();
 	{
 		pxHeapStats->xAvailableHeapSpaceInBytes = xFreeBytesRemaining;
 		pxHeapStats->xNumberOfSuccessfulAllocations = xNumberOfSuccessfulAllocations;
 		pxHeapStats->xNumberOfSuccessfulFrees = xNumberOfSuccessfulFrees;
 		pxHeapStats->xMinimumEverFreeBytesRemaining = xMinimumEverFreeBytesRemaining;
 	}
 	taskEXIT_CRITICAL();
 }
	/*
	* FreeRTOS Kernel V10.3.1
	* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy of
	* this software and associated documentation files (the "Software"), to deal in
	* the Software without restriction, including without limitation the rights to
	* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
	* the Software, and to permit persons to whom the Software is furnished to do so,
	* subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in all
	* copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
	* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
	* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
	* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*
	* http://www.FreeRTOS.org
	* http://aws.amazon.com/freertos
	*
	* 1 tab == 4 spaces!
	*/

	/*
	* 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>

	/* 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

	#if( configSUPPORT_DYNAMIC_ALLOCATION == 0 )
	#error This file must not be used if configSUPPORT_DYNAMIC_ALLOCATION is 0
	#endif

	/* Block sizes must not get too small. */
	#define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( xHeapStructSize << 1 ) )

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

	/* Allocate the memory for the heap. */
	#if( configAPPLICATION_ALLOCATED_HEAP == 1 )
	/* The application writer has already defined the array used for the RTOS
	heap - probably so it can be placed in a special segment or address. */
	extern uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
	#else
	static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
	#endif /* configAPPLICATION_ALLOCATED_HEAP */

	/* 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 size_t xHeapStructSize = ( sizeof( BlockLink_t ) + ( ( size_t ) ( portBYTE_ALIGNMENT - 1 ) ) ) & ~( ( 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 calls to allocate and free memory as well as the
	number of free bytes remaining, but says nothing about fragmentation. */
	static size_t xFreeBytesRemaining = 0U;
	static size_t xMinimumEverFreeBytesRemaining = 0U;
	static size_t xNumberOfSuccessfulAllocations = 0;
	static size_t xNumberOfSuccessfulFrees = 0;

	/* 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 *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 += xHeapStructSize;

	/* 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 ) );
	configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 );
	}
	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 ) + xHeapStructSize );

	/* 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 );
	configASSERT( ( ( ( size_t ) pxNewBlockLink ) & portBYTE_ALIGNMENT_MASK ) == 0 );

	/* 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. */
	pxBlock->xBlockSize \|= xBlockAllocatedBit;
	pxBlock->pxNextFreeBlock = NULL;
	xNumberOfSuccessfulAllocations++;
	}
	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

	configASSERT( ( ( ( size_t ) pvReturn ) & ( size_t ) portBYTE_ALIGNMENT_MASK ) == 0 );
	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 -= xHeapStructSize;

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

	/* Check the block is actually allocated. */
	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 ) );
	xNumberOfSuccessfulFrees++;
	}
	( 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. */
	}
	/-----------------------------------------------------------/

	static void prvHeapInit( void )
	{
	BlockLink_t *pxFirstFreeBlock;
	uint8_t *pucAlignedHeap;
	size_t uxAddress;
	size_t xTotalHeapSize = configTOTAL_HEAP_SIZE;

	/* Ensure the heap starts on a correctly aligned boundary. */
	uxAddress = ( size_t ) ucHeap;

	if( ( uxAddress & portBYTE_ALIGNMENT_MASK ) != 0 )
	{
	uxAddress += ( portBYTE_ALIGNMENT - 1 );
	uxAddress &= ~( ( size_t ) portBYTE_ALIGNMENT_MASK );
	xTotalHeapSize -= uxAddress - ( size_t ) ucHeap;
	}

	pucAlignedHeap = ( uint8_t * ) uxAddress;

	/* 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 * ) pucAlignedHeap;
	xStart.xBlockSize = ( size_t ) 0;

	/* pxEnd is used to mark the end of the list of free blocks and is inserted
	at the end of the heap space. */
	uxAddress = ( ( size_t ) pucAlignedHeap ) + xTotalHeapSize;
	uxAddress -= xHeapStructSize;
	uxAddress &= ~( ( size_t ) portBYTE_ALIGNMENT_MASK );
	pxEnd = ( void * ) uxAddress;
	pxEnd->xBlockSize = 0;
	pxEnd->pxNextFreeBlock = NULL;

	/* To start with there is a single free block that is sized to take up the
	entire heap space, minus the space taken by pxEnd. */
	pxFirstFreeBlock = ( void * ) pucAlignedHeap;
	pxFirstFreeBlock->xBlockSize = uxAddress - ( size_t ) pxFirstFreeBlock;
	pxFirstFreeBlock->pxNextFreeBlock = pxEnd;

	/* Only one block exists - and it covers the entire usable heap space. */
	xMinimumEverFreeBytesRemaining = pxFirstFreeBlock->xBlockSize;
	xFreeBytesRemaining = pxFirstFreeBlock->xBlockSize;

	/* 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 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();
	}
	}
	/-----------------------------------------------------------/

	void vPortGetHeapStats( HeapStats_t *pxHeapStats )
	{
	BlockLink_t *pxBlock;
	size_t xBlocks = 0, xMaxSize = 0, xMinSize = portMAX_DELAY; /* portMAX_DELAY used as a portable way of getting the maximum value. */

	vTaskSuspendAll();
	{
	pxBlock = xStart.pxNextFreeBlock;

	/* pxBlock will be NULL if the heap has not been initialised. The heap
	is initialised automatically when the first allocation is made. */
	if( pxBlock != NULL )
	{
	do
	{
	/* Increment the number of blocks and record the largest block seen
	so far. */
	xBlocks++;

	if( pxBlock->xBlockSize > xMaxSize )
	{
	xMaxSize = pxBlock->xBlockSize;
	}

	if( pxBlock->xBlockSize < xMinSize )
	{
	xMinSize = pxBlock->xBlockSize;
	}

	/* Move to the next block in the chain until the last block is
	reached. */
	pxBlock = pxBlock->pxNextFreeBlock;
	} while( pxBlock != pxEnd );
	}
	}
	xTaskResumeAll();

	pxHeapStats->xSizeOfLargestFreeBlockInBytes = xMaxSize;
	pxHeapStats->xSizeOfSmallestFreeBlockInBytes = xMinSize;
	pxHeapStats->xNumberOfFreeBlocks = xBlocks;

	taskENTER_CRITICAL();
	{
	pxHeapStats->xAvailableHeapSpaceInBytes = xFreeBytesRemaining;
	pxHeapStats->xNumberOfSuccessfulAllocations = xNumberOfSuccessfulAllocations;
	pxHeapStats->xNumberOfSuccessfulFrees = xNumberOfSuccessfulFrees;
	pxHeapStats->xMinimumEverFreeBytesRemaining = xMinimumEverFreeBytesRemaining;
	}
	taskEXIT_CRITICAL();
	}