unsigned long ulGetEMACRxData( void )
{
unsigned long ulLen = 0;
long lIndex;

	if( EMAC->RxProduceIndex != EMAC->RxConsumeIndex )
	{
		/* Mark the current buffer as free as uip_buf is going to be set to
		the buffer that contains the received data. */
		prvReturnBuffer( uip_buf );

		ulLen = ( RX_STAT_INFO( EMAC->RxConsumeIndex ) & RINFO_SIZE ) - 3;
		uip_buf = ( unsigned char * ) RX_DESC_PACKET( EMAC->RxConsumeIndex );

		/* Allocate a new buffer to the descriptor. */
        RX_DESC_PACKET( EMAC->RxConsumeIndex ) = ( unsigned long ) prvGetNextBuffer();

		/* Move the consume index onto the next position, ensuring it wraps to
		the beginning at the appropriate place. */
		lIndex = EMAC->RxConsumeIndex;

		lIndex++;
		if( lIndex >= NUM_RX_FRAG )
		{
			lIndex = 0;
		}

		EMAC->RxConsumeIndex = lIndex;
	}

	return ulLen;
}

void vSendEMACTxData( unsigned short usTxDataLen )
{
unsigned long ulAttempts = 0UL;

	/* Check to see if the Tx descriptor is free, indicated by its buffer being
	NULL. */
	while( TX_DESC_PACKET( emacTX_DESC_INDEX ) != ( unsigned long ) NULL )
	{
		/* Wait for the Tx descriptor to become available. */
		vTaskDelay( emacBUFFER_WAIT_DELAY );

		ulAttempts++;
		if( ulAttempts > emacBUFFER_WAIT_ATTEMPTS )
		{
			/* Something has gone wrong as the Tx descriptor is still in use.
			Clear it down manually, the data it was sending will probably be
			lost. */
			prvReturnBuffer( ( unsigned char * ) TX_DESC_PACKET( emacTX_DESC_INDEX ) );
			break;
		}
	}

	/* Setup the Tx descriptor for transmission.  Remember the length of the
	data being sent so the second descriptor can be used to send it again from
	within the ISR. */
	usSendLen = usTxDataLen;
	TX_DESC_PACKET( emacTX_DESC_INDEX ) = ( unsigned long ) uip_buf;
	TX_DESC_CTRL( emacTX_DESC_INDEX ) = ( usTxDataLen | TCTRL_LAST | TCTRL_INT );
	EMAC->TxProduceIndex = ( emacTX_DESC_INDEX + 1 );

	/* uip_buf is being sent by the Tx descriptor.  Allocate a new buffer. */
	uip_buf = prvGetNextBuffer();
}

unsigned long ulEMACRead( void )
{
unsigned long ulBytesReceived;

	ulBytesReceived = prvCheckRxFifoStatus();

	if( ulBytesReceived > 0 )
	{
		/* Mark the pxDescriptor buffer as free as uip_buf is going to be set to
		the buffer that contains the received data. */
		prvReturnBuffer( uip_buf );

		/* Point uip_buf to the data about ot be processed. */
		uip_buf = ( void * ) pxCurrentRxDesc->buf_p;
		
		/* Allocate a new buffer to the descriptor, as uip_buf is now using it's
		old descriptor. */
		pxCurrentRxDesc->buf_p = prvGetNextBuffer();

		/* Prepare the descriptor to go again. */
		pxCurrentRxDesc->status &= ~( FP1 | FP0 );
		pxCurrentRxDesc->status |= ACT;

		/* Move onto the next buffer in the ring. */
		pxCurrentRxDesc = pxCurrentRxDesc->next;
		
		if( EDMAC.EDRRR.LONG == 0x00000000L )
		{
			/* Restart Ethernet if it has stopped */
			EDMAC.EDRRR.LONG = 0x00000001L;
		}
	}

	return ulBytesReceived;
}

long lEMACInit( void )
{
long lReturn = pdPASS;
unsigned long ulID1, ulID2;

	/* Reset peripherals, configure port pins and registers. */
	prvSetupEMACHardware();

	/* Check the PHY part number is as expected. */
	ulID1 = prvReadPHY( PHY_REG_IDR1, &lReturn );
	ulID2 = prvReadPHY( PHY_REG_IDR2, &lReturn );
	if( ( (ulID1 << 16UL ) | ( ulID2 & 0xFFFFUL ) ) == KS8721_ID )
	{
		/* Set the Ethernet MAC Address registers */
		EMAC->SA0 = ( configMAC_ADDR0 << 8 ) | configMAC_ADDR1;
		EMAC->SA1 = ( configMAC_ADDR2 << 8 ) | configMAC_ADDR3;
		EMAC->SA2 = ( configMAC_ADDR4 << 8 ) | configMAC_ADDR5;

		/* Initialize Tx and Rx DMA Descriptors */
		prvInitDescriptors();

		/* Receive broadcast and perfect match packets */
		EMAC->RxFilterCtrl = RFC_UCAST_EN | RFC_BCAST_EN | RFC_PERFECT_EN;

		/* Setup the PHY. */
		prvConfigurePHY();
	}
	else
	{
		lReturn = pdFAIL;
	}

	/* Check the link status. */
	if( lReturn == pdPASS )
	{
		lReturn = prvSetupLinkStatus();
	}

	if( lReturn == pdPASS )
	{
		/* Initialise uip_buf to ensure it points somewhere valid. */
		uip_buf = prvGetNextBuffer();

		/* Reset all interrupts */
		EMAC->IntClear = ( INT_RX_OVERRUN | INT_RX_ERR | INT_RX_FIN | INT_RX_DONE | INT_TX_UNDERRUN | INT_TX_ERR | INT_TX_FIN | INT_TX_DONE | INT_SOFT_INT | INT_WAKEUP );

		/* Enable receive and transmit mode of MAC Ethernet core */
		EMAC->Command |= ( CR_RX_EN | CR_TX_EN );
		EMAC->MAC1 |= MAC1_REC_EN;
	}

	return lReturn;
}

void vEMACWrite( void )
{
long x;

	/* Wait until the second transmission of the last packet has completed. */
	for( x = 0; x < emacTX_WAIT_ATTEMPTS; x++ )
	{
		if( ( xTxDescriptors[ 1 ].status & ACT ) != 0 )
		{
			/* Descriptor is still active. */
			vTaskDelay( emacTX_WAIT_DELAY_ms );
		}
		else
		{
			break;
		}
	}
	
	/* Is the descriptor free after waiting for it? */
	if( ( xTxDescriptors[ 1 ].status & ACT ) != 0 )
	{
		/* Something has gone wrong. */
		prvResetEverything();
	}
	
	/* Setup both descriptors to transmit the frame. */
	xTxDescriptors[ 0 ].buf_p = ( char * ) uip_buf;
	xTxDescriptors[ 0 ].bufsize = uip_len;	
	xTxDescriptors[ 1 ].buf_p = ( char * ) uip_buf;
	xTxDescriptors[ 1 ].bufsize = uip_len;

	/* uip_buf is being sent by the Tx descriptor.  Allocate a new buffer
	for use by the stack. */
	uip_buf = prvGetNextBuffer();

	/* Clear previous settings and go. */
	xTxDescriptors[0].status &= ~( FP1 | FP0 );
	xTxDescriptors[0].status |= ( FP1 | FP0 | ACT );
	xTxDescriptors[1].status &= ~( FP1 | FP0 );
	xTxDescriptors[1].status |= ( FP1 | FP0 | ACT );

	EDMAC.EDTRR.LONG = 0x00000001;
}

void vEMACWrite( void )
{
long x;

	/* Wait until the second transmission of the last packet has completed. */
	for( x = 0; x < emacTX_WAIT_ATTEMPTS; x++ )
	{
		if( ( xTxDescriptors[ 1 ].status & TX_BD_R ) != 0 )
		{
			/* Descriptor is still active. */
			vTaskDelay( emacTX_WAIT_DELAY_ms );
		}
		else
		{
			break;
		}
	}
	
	/* Is the descriptor free after waiting for it? */
	if( ( xTxDescriptors[ 1 ].status & TX_BD_R ) != 0 )
	{
		/* Something has gone wrong. */
		prvResetEverything();
	}
	
	/* Setup both descriptors to transmit the frame. */
	xTxDescriptors[ 0 ].data = ( uint8_t * ) __REV( ( unsigned long ) uip_buf );
	xTxDescriptors[ 0 ].length = __REVSH( uip_len );
	xTxDescriptors[ 1 ].data = ( uint8_t * ) __REV( ( unsigned long ) uip_buf );
	xTxDescriptors[ 1 ].length = __REVSH( uip_len );

	/* uip_buf is being sent by the Tx descriptor.  Allocate a new buffer
	for use by the stack. */
	uip_buf = prvGetNextBuffer();

	/* Clear previous settings and go. */
	xTxDescriptors[ 0 ].status |= ( TX_BD_R | TX_BD_L );
	xTxDescriptors[ 1 ].status |= ( TX_BD_R | TX_BD_L );

	/* Start the Tx. */
	ENET_TDAR = ENET_TDAR_TDAR_MASK;
}

unsigned short usEMACRead( void )
{
unsigned short usBytesReceived;

	usBytesReceived = prvCheckRxStatus();
	usBytesReceived = __REVSH( usBytesReceived );

	if( usBytesReceived > 0 )
	{
		/* Mark the pxDescriptor buffer as free as uip_buf is going to be set to
		the buffer that contains the received data. */
		prvReturnBuffer( uip_buf );

		/* Point uip_buf to the data about to be processed. */
		uip_buf = ( void * ) pxCurrentRxDesc->data;
		uip_buf = ( void * ) __REV( ( unsigned long ) uip_buf );
		
		/* Allocate a new buffer to the descriptor, as uip_buf is now using it's
		old descriptor. */
		pxCurrentRxDesc->data = ( uint8_t * ) prvGetNextBuffer();
		pxCurrentRxDesc->data = ( uint8_t* ) __REV( ( unsigned long ) pxCurrentRxDesc->data );

		/* Prepare the descriptor to go again. */
		pxCurrentRxDesc->status |= RX_BD_E;

		/* Move onto the next buffer in the ring. */
		ulRxDescriptorIndex++;
		if( ulRxDescriptorIndex >= emacNUM_RX_DESCRIPTORS )
		{
			ulRxDescriptorIndex = 0UL;
		}
		pxCurrentRxDesc = &( xRxDescriptors[ ulRxDescriptorIndex ] );
		
		/* Restart Ethernet if it has stopped */
		ENET_RDAR = ENET_RDAR_RDAR_MASK;
	}

	return usBytesReceived;
}