FreeRTOS-Kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-UDP/portable/BufferManagement/BufferAllocation_2.c

/*
 * FreeRTOS+UDP V1.0.0 (C) 2013 Real Time Engineers ltd.
 *
 * FreeRTOS+UDP is an add-on component to FreeRTOS.  It is not, in itself, part
 * of the FreeRTOS kernel.  FreeRTOS+UDP is licensed separately from FreeRTOS,
 * and uses a different license to FreeRTOS.  FreeRTOS+UDP uses a dual license
 * model, information on which is provided below:
 *
 * - Open source licensing -
 * FreeRTOS+UDP is a free download and may be used, modified and distributed
 * without charge provided the user adheres to version two of the GNU General
 * Public license (GPL) and does not remove the copyright notice or this text.
 * The GPL V2 text is available on the gnu.org web site, and on the following
 * URL: http://www.FreeRTOS.org/gpl-2.0.txt
 *
 * - Commercial licensing -
 * Businesses and individuals who wish to incorporate FreeRTOS+UDP into
 * proprietary software for redistribution in any form must first obtain a
 * (very) low cost commercial license - and in-so-doing support the maintenance,
 * support and further development of the FreeRTOS+UDP product.  Commercial
 * licenses can be obtained from http://shop.freertos.org and do not require any
 * source files to be changed.
 *
 * FreeRTOS+UDP is distributed in the hope that it will be useful.  You cannot
 * use FreeRTOS+UDP unless you agree that you use the software 'as is'.
 * FreeRTOS+UDP is provided WITHOUT ANY WARRANTY; without even the implied
 * warranties of NON-INFRINGEMENT, MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. Real Time Engineers Ltd. disclaims all conditions and terms, be they
 * implied, expressed, or statutory.
 *
 * 1 tab == 4 spaces!
 *
 * http://www.FreeRTOS.org
 * http://www.FreeRTOS.org/udp
 *
 */

/******************************************************************************
 *
 * See the following web page for essential buffer allocation scheme usage and 
 * configuration details:
 * http://www.FreeRTOS.org/FreeRTOS-Plus/FreeRTOS_Plus_UDP/Embedded_Ethernet_Buffer_Management.shtml
 *
 ******************************************************************************/

/* THIS FILE SHOULD NOT BE USED IF THE PROJECT INCLUDES A MEMORY ALLOCATOR
THAT WILL FRAGMENT THE HEAP MEMORY.  For example, heap_2 must not be used,
heap_4 can be used. */


/* Standard includes. */
#include <stdint.h>

/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "semphr.h"

/* FreeRTOS+UDP includes. */
#include "FreeRTOS_UDP_IP.h"
#include "FreeRTOS_IP_Private.h"
#include "NetworkInterface.h"

/* For an Ethernet interrupt to be able to obtain a network buffer there must
be at least this number of buffers available. */
#define ipINTERRUPT_BUFFER_GET_THRESHOLD	( 3 )

/* A list of free (available) xNetworkBufferDescriptor_t structures. */
static xList xFreeBuffersList;

/* Declares the pool of xNetworkBufferDescriptor_t structures that are available to the
system.  All the network buffers referenced from xFreeBuffersList exist in this
array.  The array is not accessed directly except during initialisation, when
the xFreeBuffersList is filled (as all the buffers are free when the system is
booted). */
static xNetworkBufferDescriptor_t xNetworkBuffers[ ipconfigNUM_NETWORK_BUFFERS ];

/* The semaphore used to obtain network buffers. */
static xSemaphoreHandle xNetworkBufferSemaphore = NULL;

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

portBASE_TYPE xNetworkBuffersInitialise( void )
{
portBASE_TYPE xReturn, x;

	/* Only initialise the buffers and their associated kernel objects if they
	have not been initialised before. */
	if( xNetworkBufferSemaphore == NULL )
	{
		xNetworkBufferSemaphore = xSemaphoreCreateCounting( ipconfigNUM_NETWORK_BUFFERS, ipconfigNUM_NETWORK_BUFFERS );
		configASSERT( xNetworkBufferSemaphore );
		vQueueAddToRegistry( xNetworkBufferSemaphore, ( signed char * ) "NetBufSem" );

		/* If the trace recorder code is included name the semaphore for viewing
		in FreeRTOS+Trace.  */
		#if ipconfigINCLUDE_EXAMPLE_FREERTOS_PLUS_TRACE_CALLS == 1
		{
			extern xQueueHandle xNetworkEventQueue;
			vTraceSetQueueName( xNetworkEventQueue, "IPStackEvent" );
			vTraceSetQueueName( xNetworkBufferSemaphore, "NetworkBufferCount" );
		}
		#endif /*  ipconfigINCLUDE_EXAMPLE_FREERTOS_PLUS_TRACE_CALLS == 1 */

		if( xNetworkBufferSemaphore != NULL )
		{
			vListInitialise( &xFreeBuffersList );

			/* Initialise all the network buffers.  No storage is allocated to
			the buffers yet. */
			for( x = 0; x < ipconfigNUM_NETWORK_BUFFERS; x++ )
			{
				/* Initialise and set the owner of the buffer list items. */
				xNetworkBuffers[ x ].pucEthernetBuffer = NULL;
				vListInitialiseItem( &( xNetworkBuffers[ x ].xBufferListItem ) );
				listSET_LIST_ITEM_OWNER( &( xNetworkBuffers[ x ].xBufferListItem ), &xNetworkBuffers[ x ] );

				/* Currently, all buffers are available for use. */
				vListInsert( &xFreeBuffersList, &( xNetworkBuffers[ x ].xBufferListItem ) );
			}
		}
	}

	if( xNetworkBufferSemaphore == NULL )
	{
		xReturn = pdFAIL;
	}
	else
	{
		xReturn = pdPASS;
	}

	return xReturn;
}
/*-----------------------------------------------------------*/

uint8_t *pucEthernetBufferGet( size_t *pxRequestedSizeBytes )
{
uint8_t *pucEthernetBuffer;

	if( *pxRequestedSizeBytes < sizeof( xARPPacket_t ) )
	{
		/* Buffers must be at least large enough to hold ARP packets, otherwise
		nothing can be done. */
		*pxRequestedSizeBytes = sizeof( xARPPacket_t );
	}

	/* Allocate a buffer large enough to store the requested Ethernet frame size
	and a pointer to a network buffer structure (hence the addition of
	ipBUFFER_PADDING bytes). */
	pucEthernetBuffer = ( uint8_t * ) pvPortMalloc( *pxRequestedSizeBytes + ipBUFFER_PADDING );

	/* Enough space is left at the start of the buffer to place a pointer to
	the network buffer structure that references this Ethernet buffer.  Return
	a pointer to the start of the Ethernet buffer itself. */
	pucEthernetBuffer += ipBUFFER_PADDING;

	return pucEthernetBuffer;
}
/*-----------------------------------------------------------*/

void vEthernetBufferRelease( uint8_t *pucEthernetBuffer )
{
	/* There is space before the Ethernet buffer in which a pointer to the
	network buffer that references this Ethernet buffer is stored.  Remove the
	space before freeing the buffer. */
	if( pucEthernetBuffer != NULL )
	{
		pucEthernetBuffer -= ipBUFFER_PADDING;
		vPortFree( ( void * ) pucEthernetBuffer );
	}
}
/*-----------------------------------------------------------*/

xNetworkBufferDescriptor_t *pxNetworkBufferGet( size_t xRequestedSizeBytes, portTickType xBlockTimeTicks )
{
xNetworkBufferDescriptor_t *pxReturn = NULL;

	if( ( xRequestedSizeBytes != 0 ) && ( xRequestedSizeBytes < sizeof( xARPPacket_t ) ) )
	{
		/* ARP packets can replace application packets, so the storage must be
		at least large enough to hold an ARP. */
		xRequestedSizeBytes = sizeof( xARPPacket_t );
	}

	/* If there is a semaphore available, there is a network buffer available. */
	if( xSemaphoreTake( xNetworkBufferSemaphore, xBlockTimeTicks ) == pdPASS )
	{
		/* Protect the structure as it is accessed from tasks and interrupts. */
		taskENTER_CRITICAL();
		{
			pxReturn = ( xNetworkBufferDescriptor_t * ) listGET_OWNER_OF_HEAD_ENTRY( &xFreeBuffersList );
			uxListRemove( &( pxReturn->xBufferListItem ) );
		}
		taskEXIT_CRITICAL();

		/* Allocate storage of exactly the requested size to the buffer. */
		configASSERT( pxReturn->pucEthernetBuffer == NULL );
		if( xRequestedSizeBytes > 0 )
		{
			/* Extra space is obtained so a pointer to the network buffer can
			be stored at the beginning of the buffer. */
			pxReturn->pucEthernetBuffer = ( uint8_t * ) pvPortMalloc( xRequestedSizeBytes + ipBUFFER_PADDING );

			if( pxReturn->pucEthernetBuffer == NULL )
			{
				/* The attempt to allocate storage for the buffer payload failed,
				so the network buffer structure cannot be used and must be
				released. */
				vNetworkBufferRelease( pxReturn );
				pxReturn = NULL;
			}
			else
			{
				/* Store a pointer to the network buffer structure in the
				buffer storage area, then move the buffer pointer on past the
				stored pointer so the pointer value is not overwritten by the
				application when the buffer is used. */
				*( ( xNetworkBufferDescriptor_t ** ) ( pxReturn->pucEthernetBuffer ) ) = pxReturn;
				pxReturn->pucEthernetBuffer += ipBUFFER_PADDING;
				iptraceNETWORK_BUFFER_OBTAINED( pxReturn );

				/* Store the actual size of the allocated buffer, which may be
				greater than the requested size. */
				pxReturn->xDataLength = xRequestedSizeBytes;
			}
		}
		else
		{
			iptraceNETWORK_BUFFER_OBTAINED( pxReturn );
		}
	}

	if( pxReturn == NULL )
	{
		iptraceFAILED_TO_OBTAIN_NETWORK_BUFFER();
	}

	return pxReturn;
}
/*-----------------------------------------------------------*/

void vNetworkBufferRelease( xNetworkBufferDescriptor_t * const pxNetworkBuffer )
{
portBASE_TYPE xListItemAlreadyInFreeList;

	/* Ensure the buffer is returned to the list of free buffers before the
	counting semaphore is 'given' to say a buffer is available.  Release the
	storage allocated to the buffer payload.  THIS FILE SHOULD NOT BE USED
	IF THE PROJECT INCLUDES A MEMORY ALLOCATOR THAT WILL FRAGMENT THE HEAP
	MEMORY.  For example, heap_2 must not be used, heap_4 can be used. */
	vEthernetBufferRelease( pxNetworkBuffer->pucEthernetBuffer );
	pxNetworkBuffer->pucEthernetBuffer = NULL;

	taskENTER_CRITICAL();
	{
		xListItemAlreadyInFreeList = listIS_CONTAINED_WITHIN( &xFreeBuffersList, &( pxNetworkBuffer->xBufferListItem ) );

		if( xListItemAlreadyInFreeList == pdFALSE )
		{
			vListInsertEnd( &xFreeBuffersList, &( pxNetworkBuffer->xBufferListItem ) );
		}

		configASSERT( xListItemAlreadyInFreeList == pdFALSE );
	}
	taskEXIT_CRITICAL();

	xSemaphoreGive( xNetworkBufferSemaphore );
	iptraceNETWORK_BUFFER_RELEASED( pxNetworkBuffer );
}
/*-----------------------------------------------------------*/

#if( ipconfigINCLUDE_TEST_CODE == 1 )

unsigned portBASE_TYPE uxGetNumberOfFreeNetworkBuffers( void )
{
	return listCURRENT_LIST_LENGTH( &xFreeBuffersList );
}

#endif /* ipconfigINCLUDE_TEST_CODE */