FreeRTOS-Plus/Source/FreeRTOS-Plus-UDP/portable/BufferManagement/BufferAllocation_1.c

/*
 * FreeRTOS+UDP V1.0.4
 * Copyright (C) 2017 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!
 */


/******************************************************************************
 *
 * 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
 *
 ******************************************************************************/


/* 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;

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

BaseType_t xNetworkBuffersInitialise( void )
{
BaseType_t 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 );

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

			/* Initialise all the network buffers.  The buffer storage comes
			from the network interface, and different hardware has different
			requirements. */
			vNetworkInterfaceAllocateRAMToBuffers( xNetworkBuffers );
			for( x = 0; x < ipconfigNUM_NETWORK_BUFFERS; x++ )
			{
				/* Initialise and set the owner of the buffer list items. */
				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;
}
/*-----------------------------------------------------------*/

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

	/*_RB_ The current implementation only has a single size memory block, so
	the requested size parameter is not used (yet). */
	( void ) xRequestedSizeBytes;

	/* 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();
		iptraceNETWORK_BUFFER_OBTAINED( pxReturn );
	}
	else
	{
		iptraceFAILED_TO_OBTAIN_NETWORK_BUFFER();
	}

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

xNetworkBufferDescriptor_t *pxNetworkBufferGetFromISR( size_t xRequestedSizeBytes )
{
xNetworkBufferDescriptor_t *pxReturn = NULL;
UBaseType_t uxSavedInterruptStatus;

	/*_RB_ The current implementation only has a single size memory block, so
	the requested size parameter is not used (yet). */
	( void ) xRequestedSizeBytes;

	/* If there is a semaphore available then there is a buffer available, but,
	as this is called from an interrupt, only take a buffer if there are at
	least ipINTERRUPT_BUFFER_GET_THRESHOLD buffers remaining.  This prevents,
	to a certain degree at least, a rapidly executing interrupt exhausting
	buffer and in so doing preventing tasks from continuing. */
	if( uxQueueMessagesWaitingFromISR( ( xQueueHandle ) xNetworkBufferSemaphore ) > ipINTERRUPT_BUFFER_GET_THRESHOLD )
	{
		if( xSemaphoreTakeFromISR( xNetworkBufferSemaphore, NULL ) == pdPASS )
		{
			/* Protect the structure as it is accessed from tasks and interrupts. */
			uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
			{
				pxReturn = ( xNetworkBufferDescriptor_t * ) listGET_OWNER_OF_HEAD_ENTRY( &xFreeBuffersList );
				uxListRemove( &( pxReturn->xBufferListItem ) );
			}
			portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

			iptraceNETWORK_BUFFER_OBTAINED_FROM_ISR( pxReturn );
		}
	}

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

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

BaseType_t vNetworkBufferReleaseFromISR( xNetworkBufferDescriptor_t * const pxNetworkBuffer )
{
UBaseType_t uxSavedInterruptStatus;
BaseType_t xHigherPriorityTaskWoken = pdFALSE;

	/* Ensure the buffer is returned to the list of free buffers before the
	counting semaphore is 'given' to say a buffer is available. */
	uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
	{
		vListInsertEnd( &xFreeBuffersList, &( pxNetworkBuffer->xBufferListItem ) );
	}
	portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

	xSemaphoreGiveFromISR( xNetworkBufferSemaphore, &xHigherPriorityTaskWoken );
	iptraceNETWORK_BUFFER_RELEASED( pxNetworkBuffer );

	return xHigherPriorityTaskWoken;
}
/*-----------------------------------------------------------*/

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

	/* Ensure the buffer is returned to the list of free buffers before the
	counting semaphore is 'given' to say a buffer is available. */
	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 )

UBaseType_t uxGetNumberOfFreeNetworkBuffers( void )
{
	return listCURRENT_LIST_LENGTH( &xFreeBuffersList );
}

#endif /* ipconfigINCLUDE_TEST_CODE */