FreeRTOSV7.2.0/FreeRTOS/Source/portable/MemMang/heap_1.c

/*
    FreeRTOS V7.2.0 - Copyright (C) 2012 Real Time Engineers Ltd.
	

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    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
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    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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*/


/*
 * The simplest possible implementation of pvPortMalloc().  Note that this
 * implementation does NOT allow allocated memory to be freed again.
 *
 * See heap_2.c, heap_3.c and heap_4.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

/* Allocate the memory for the heap.  The struct is used to force byte
alignment without using any non-portable code. */
static union xRTOS_HEAP
{
	#if portBYTE_ALIGNMENT == 8
		volatile portDOUBLE dDummy;
	#else
		volatile unsigned long ulDummy;
	#endif	
	unsigned char ucHeap[ configTOTAL_HEAP_SIZE ];
} xHeap;

static size_t xNextFreeByte = ( size_t ) 0;
/*-----------------------------------------------------------*/

void *pvPortMalloc( size_t xWantedSize )
{
void *pvReturn = NULL; 

	/* Ensure that blocks are always aligned to the required number of bytes. */
	#if portBYTE_ALIGNMENT != 1
		if( xWantedSize & portBYTE_ALIGNMENT_MASK )
		{
			/* Byte alignment required. */
			xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
		}
	#endif

	vTaskSuspendAll();
	{
		/* Check there is enough room left for the allocation. */
		if( ( ( xNextFreeByte + xWantedSize ) < configTOTAL_HEAP_SIZE ) &&
			( ( xNextFreeByte + xWantedSize ) > xNextFreeByte )	)/* Check for overflow. */
		{
			/* Return the next free byte then increment the index past this
			block. */
			pvReturn = &( xHeap.ucHeap[ xNextFreeByte ] );
			xNextFreeByte += xWantedSize;			
		}	
	}
	xTaskResumeAll();
	
	#if( configUSE_MALLOC_FAILED_HOOK == 1 )
	{
		if( pvReturn == NULL )
		{
			extern void vApplicationMallocFailedHook( void );
			vApplicationMallocFailedHook();
		}
	}
	#endif	

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

void vPortFree( void *pv )
{
	/* Memory cannot be freed using this scheme.  See heap_2.c, heap_3.c and
	heap_4.c for alternative implementations, and the memory management pages of 
	http://www.FreeRTOS.org for more information. */
	( void ) pv;
	
	/* Force an assert as it is invalid to call this function. */
	configASSERT( pv == NULL );
}
/*-----------------------------------------------------------*/

void vPortInitialiseBlocks( void )
{
	/* Only required when static memory is not cleared. */
	xNextFreeByte = ( size_t ) 0;
}
/*-----------------------------------------------------------*/

size_t xPortGetFreeHeapSize( void )
{
	return ( configTOTAL_HEAP_SIZE - xNextFreeByte );
}