path: root/Demo/WizNET_DEMO_GCC_ARM7/TCP.c

/*
	FreeRTOS.org V5.2.0 - Copyright (C) 2003-2009 Richard Barry.

	This file is part of the FreeRTOS.org distribution.

	FreeRTOS.org is free software; you can redistribute it and/or modify it 
	under the terms of the GNU General Public License (version 2) as published
	by the Free Software Foundation and modified by the FreeRTOS exception.

	FreeRTOS.org is distributed in the hope that it will be useful,	but WITHOUT
	ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
	FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for 
	more details.

	You should have received a copy of the GNU General Public License along 
	with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59 
	Temple Place, Suite 330, Boston, MA  02111-1307  USA.

	A special exception to the GPL is included to allow you to distribute a 
	combined work that includes FreeRTOS.org without being obliged to provide
	the source code for any proprietary components.  See the licensing section
	of http://www.FreeRTOS.org for full details.


	***************************************************************************
	*                                                                         *
	* Get the FreeRTOS eBook!  See http://www.FreeRTOS.org/Documentation      *
	*                                                                         *
	* This is a concise, step by step, 'hands on' guide that describes both   *
	* general multitasking concepts and FreeRTOS specifics. It presents and   *
	* explains numerous examples that are written using the FreeRTOS API.     *
	* Full source code for all the examples is provided in an accompanying    *
	* .zip file.                                                              *
	*                                                                         *
	***************************************************************************

	1 tab == 4 spaces!

	Please ensure to read the configuration and relevant port sections of the
	online documentation.

	http://www.FreeRTOS.org - Documentation, latest information, license and
	contact details.

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*/

/*
	Changes from V3.2.3
	
	+ Modified char* types to compile without warning when using GCC V4.0.1.
	+ Corrected the address to which the MAC address is written.  Thanks to
	  Bill Knight for this correction.

	Changes from V3.2.4

	+ Changed the default MAC address to something more realistic.

*/

/* Standard includes. */
#include <stdlib.h>
#include <string.h>

/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
#include "semphr.h"
#include "tcp.h"
#include "serial.h"

/* Application includes. */
#include "i2c.h"
#include "html_pages.h"

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

/* Hardwired i2c address of the WIZNet device. */
#define tcpDEVICE_ADDRESS 				( ( unsigned portCHAR ) 0x00 )

/* Constants used to configure the Tx and Rx buffer sizes within the WIZnet
device. */
#define tcp8K_RX						( ( unsigned portCHAR ) 0x03 )
#define tcp8K_TX						( ( unsigned portCHAR ) 0x03 )

/* Constants used to generate the WIZnet internal buffer addresses. */
#define tcpSINGLE_SOCKET_ADDR_MASK		( ( unsigned portLONG ) 0x1fff )
#define tcpSINGLE_SOCKET_ADDR_OFFSET	( ( unsigned portLONG ) 0x4000 )

/* Bit definitions of the commands that can be sent to the command register. */
#define tcpRESET_CMD					( ( unsigned portCHAR ) 0x80 )
#define tcpSYS_INIT_CMD					( ( unsigned portCHAR ) 0x01 )
#define tcpSOCK_STREAM					( ( unsigned portCHAR ) 0x01 )
#define tcpSOCK_INIT					( ( unsigned portCHAR ) 0x02 )
#define tcpLISTEN_CMD					( ( unsigned portCHAR ) 0x08 )
#define tcpRECEIVE_CMD					( ( unsigned portCHAR ) 0x40 )
#define tcpDISCONNECT_CMD				( ( unsigned portCHAR ) 0x10 )
#define tcpSEND_CMD						( ( unsigned portCHAR ) 0x20 )

/* Constants required to handle the interrupts. */
#define tcpCLEAR_EINT0					( 1 )
#define i2cCLEAR_ALL_INTERRUPTS			( ( unsigned portCHAR ) 0xff )
#define i2cCHANNEL_0_ISR_ENABLE			( ( unsigned portCHAR ) 0x01 )
#define i2cCHANNEL_0_ISR_DISABLE		( ( unsigned portCHAR ) 0x00 )
#define tcpWAKE_ON_EINT0				( 1 )
#define tcpENABLE_EINT0_FUNCTION		( ( unsigned portLONG ) 0x01 )
#define tcpEINT0_VIC_CHANNEL_BIT		( ( unsigned portLONG ) 0x4000 )
#define tcpEINT0_VIC_CHANNEL			( ( unsigned portLONG ) 14 )
#define tcpEINT0_VIC_ENABLE				( ( unsigned portLONG ) 0x0020 )

/* Various delays used in the driver. */
#define tcpRESET_DELAY					( ( portTickType ) 16 / portTICK_RATE_MS )
#define tcpINIT_DELAY					( ( portTickType ) 500 / portTICK_RATE_MS  )
#define tcpLONG_DELAY					( ( portTickType ) 500 / portTICK_RATE_MS  )
#define tcpSHORT_DELAY					( ( portTickType ) 5 / portTICK_RATE_MS )
#define tcpCONNECTION_WAIT_DELAY		( ( portTickType ) 100 / portTICK_RATE_MS )
#define tcpNO_DELAY						( ( portTickType ) 0 )

/* Length of the data to read for various register reads. */
#define tcpSTATUS_READ_LEN				( ( unsigned portLONG ) 1 )
#define tcpSHADOW_READ_LEN				( ( unsigned portLONG ) 1 )
	
/* Register addresses within the WIZnet device. */
#define tcpCOMMAND_REG					( ( unsigned portSHORT ) 0x0000 )
#define tcpGATEWAY_ADDR_REG				( ( unsigned portSHORT ) 0x0080 )
#define tcpSUBNET_MASK_REG				( ( unsigned portSHORT ) 0x0084 )
#define tcpSOURCE_HA_REG				( ( unsigned portSHORT ) 0x0088 )
#define tpcSOURCE_IP_REG				( ( unsigned portSHORT ) 0x008E )
#define tpcSOCKET_OPT_REG				( ( unsigned portSHORT ) 0x00A1 )
#define tcpSOURCE_PORT_REG				( ( unsigned portSHORT ) 0x00AE )
#define tcpTX_WRITE_POINTER_REG			( ( unsigned portSHORT ) 0x0040 )
#define tcpTX_READ_POINTER_REG			( ( unsigned portSHORT ) 0x0044 )
#define tcpTX_ACK_POINTER_REG			( ( unsigned portSHORT ) 0x0018 )
#define tcpTX_MEM_SIZE_REG				( ( unsigned portSHORT ) 0x0096 )
#define tcpRX_MEM_SIZE_REG				( ( unsigned portSHORT ) 0x0095 )
#define tcpINTERRUPT_STATUS_REG			( ( unsigned portSHORT ) 0x0004 )
#define tcpTX_WRITE_SHADOW_REG			( ( unsigned portSHORT ) 0x01F0 )
#define tcpTX_ACK_SHADOW_REG			( ( unsigned portSHORT ) 0x01E2 )
#define tcpISR_MASK_REG					( ( unsigned portSHORT ) 0x0009 )
#define tcpINTERRUPT_REG				( ( unsigned portSHORT ) 0x0008 )
#define tcpSOCKET_STATE_REG				( ( unsigned portSHORT ) 0x00a0 )

/* Constants required for hardware setup. */
#define tcpRESET_ACTIVE_LOW 			( ( unsigned portLONG ) 0x20 )
#define tcpRESET_ACTIVE_HIGH 			( ( unsigned portLONG ) 0x10 )

/* Constants defining the source of the WIZnet ISR. */
#define tcpISR_SYS_INIT					( ( unsigned portCHAR ) 0x01 )
#define tcpISR_SOCKET_INIT				( ( unsigned portCHAR ) 0x02 )
#define tcpISR_ESTABLISHED				( ( unsigned portCHAR ) 0x04 )
#define tcpISR_CLOSED					( ( unsigned portCHAR ) 0x08 )
#define tcpISR_TIMEOUT					( ( unsigned portCHAR ) 0x10 )
#define tcpISR_TX_COMPLETE				( ( unsigned portCHAR ) 0x20 )
#define tcpISR_RX_COMPLETE				( ( unsigned portCHAR ) 0x40 )

/* Constants defining the socket status bits. */
#define tcpSTATUS_ESTABLISHED			( ( unsigned portCHAR ) 0x06 )
#define tcpSTATUS_LISTEN				( ( unsigned portCHAR ) 0x02 )

/* Misc constants. */
#define tcpNO_STATUS_BITS				( ( unsigned portCHAR ) 0x00 )
#define i2cNO_ADDR_REQUIRED				( ( unsigned portSHORT ) 0x0000 )
#define i2cNO_DATA_REQUIRED				( 0x0000 )
#define tcpISR_QUEUE_LENGTH				( ( unsigned portBASE_TYPE ) 10 )
#define tcpISR_QUEUE_ITEM_SIZE			( ( unsigned portBASE_TYPE ) 0 )
#define tcpBUFFER_LEN					( 4 * 1024 )
#define tcpMAX_REGISTER_LEN				( 4 )
#define tcpMAX_ATTEMPTS_TO_CHECK_BUFFER	( 6 )
#define tcpMAX_NON_LISTEN_STAUS_READS	( 5 )

/* Message definitions.  The IP address, MAC address, gateway address, etc.
is set here! */
const unsigned portCHAR const ucDataGAR[]				= { 172, 25, 218, 3 };	/* Gateway address. */
const unsigned portCHAR const ucDataMSR[]				= { 255, 255, 255, 0 };	/* Subnet mask.		*/
const unsigned portCHAR const ucDataSIPR[]				= { 172, 25, 218, 201 };/* IP address.		*/
const unsigned portCHAR const ucDataSHAR[]				= { 00, 23, 30, 41, 15, 26 }; /* MAC address - DO NOT USE THIS ON A PUBLIC NETWORK! */

/* Other fixed messages. */
const unsigned portCHAR const ucDataReset[]				= { tcpRESET_CMD }; 
const unsigned portCHAR const ucDataInit[]				= { tcpSYS_INIT_CMD }; 
const unsigned portCHAR const ucDataProtocol[]			= { tcpSOCK_STREAM };
const unsigned portCHAR const ucDataPort[]				= { 0xBA, 0xCC };
const unsigned portCHAR const ucDataSockInit[]			= { tcpSOCK_INIT };
const unsigned portCHAR const ucDataTxWritePointer[]	= { 0x11, 0x22, 0x00, 0x00 };
const unsigned portCHAR const ucDataTxAckPointer[]		= { 0x11, 0x22, 0x00, 0x00 };
const unsigned portCHAR const ucDataTxReadPointer[]		= { 0x11, 0x22, 0x00, 0x00 };
const unsigned portCHAR const ucDataListen[]			= { tcpLISTEN_CMD };
const unsigned portCHAR const ucDataReceiveCmd[]		= { tcpRECEIVE_CMD };
const unsigned portCHAR const ucDataSetTxBufSize[]		= { tcp8K_TX };
const unsigned portCHAR const ucDataSetRxBufSize[] 		= { tcp8K_RX };
const unsigned portCHAR const ucDataSend[]				= { tcpSEND_CMD };
const unsigned portCHAR const ucDataDisconnect[]		= { tcpDISCONNECT_CMD };
const unsigned portCHAR const ucDataEnableISR[]			= { i2cCHANNEL_0_ISR_ENABLE };
const unsigned portCHAR const ucDataDisableISR[]		= { i2cCHANNEL_0_ISR_DISABLE };
const unsigned portCHAR const ucDataClearInterrupt[]	= { i2cCLEAR_ALL_INTERRUPTS };

static xSemaphoreHandle xMessageComplete = NULL;
xQueueHandle xTCPISRQueue = NULL;

/* Dynamically generate and send an html page. */
static void prvSendSamplePage( void );

/* Read a register from the WIZnet device via the i2c interface. */
static void prvReadRegister( unsigned portCHAR *pucDestination, unsigned portSHORT usAddress, unsigned portLONG ulLength );

/* Send the entire Tx buffer (the Tx buffer within the WIZnet device). */
static void prvFlushBuffer( unsigned portLONG ulTxAddress );

/* Write a string to the WIZnet Tx buffer. */
static void prvWriteString( const portCHAR * const pucTxBuffer, portLONG lTxLen, unsigned portLONG *pulTxAddress );

/* Convert a number to a string. */
void ultoa( unsigned portLONG ulVal, portCHAR *pcBuffer, portLONG lIgnore );

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

void ultoa( unsigned portLONG ulVal, portCHAR *pcBuffer, portLONG lIgnore )
{
unsigned portLONG lNibble;
portLONG lIndex;

	/* Simple routine to convert an unsigned long value into a string in hex 
	format. */

	/* For each nibble in the number we are converting. */
	for( lIndex = 0; lIndex < ( sizeof( ulVal ) * 2 ); lIndex++ )
	{
		/* Take the top four bits of the number. */
		lNibble = ( ulVal >> 28 );

		/* We are converting it to a hex string, so is the number in the range
		0-10 or A-F? */
		if( lNibble < 10 )
		{
			pcBuffer[ lIndex ] = '0' + lNibble;
		}
		else
		{
			lNibble -= 10;
			pcBuffer[ lIndex ] = 'A' + lNibble;
		}

		/* Shift off the top nibble so we use the next nibble next time around. */
		ulVal <<= 4;
	}	

	/* Mark the end of the string with a null terminator. */
	pcBuffer[ lIndex ] = 0x00;
}
/*-----------------------------------------------------------*/

static void prvReadRegister( unsigned portCHAR *pucDestination, unsigned portSHORT usAddress, unsigned portLONG ulLength )
{
unsigned portCHAR ucRxBuffer[ tcpMAX_REGISTER_LEN ];

	/* Read a register value from the WIZnet device. */

	/* First write out the address of the register we want to read. */
	i2cMessage( ucRxBuffer, i2cNO_DATA_REQUIRED, tcpDEVICE_ADDRESS, usAddress, i2cWRITE, NULL, portMAX_DELAY );
	
	/* Then read back from that address. */
	i2cMessage( ( unsigned portCHAR * ) pucDestination, ulLength, tcpDEVICE_ADDRESS, i2cNO_ADDR_REQUIRED, i2cREAD, xMessageComplete, portMAX_DELAY );

	/* I2C messages are queued so use the semaphore to wait for the read to 
	complete - otherwise we will leave this function before the I2C 
	transactions have completed. */
	xSemaphoreTake( xMessageComplete, tcpLONG_DELAY );
}
/*-----------------------------------------------------------*/

void vTCPHardReset( void )
{
	/* Physical reset of the WIZnet device by using the GPIO lines to hold the 
	WIZnet reset lines active for a few milliseconds. */

	/* Make sure the interrupt from the WIZnet is disabled. */
	VICIntEnClear |= tcpEINT0_VIC_CHANNEL_BIT;

	/* If xMessageComplete is NULL then this is the first time that this 
	function has been called and the queue and semaphore used in this file
	have not yet been created. */
	if( xMessageComplete == NULL )
	{
		/* Create and obtain the semaphore used when we want to wait for an i2c
		message to be completed. */
		vSemaphoreCreateBinary( xMessageComplete );
		xSemaphoreTake( xMessageComplete, tcpNO_DELAY );

		/* Create the queue used to communicate between the WIZnet and TCP tasks. */
		xTCPISRQueue = xQueueCreate( tcpISR_QUEUE_LENGTH, tcpISR_QUEUE_ITEM_SIZE );
	}

	/* Use the GPIO to reset the network hardware. */
	GPIO_IOCLR = tcpRESET_ACTIVE_LOW;
	GPIO_IOSET = tcpRESET_ACTIVE_HIGH;

	/* Delay with the network hardware in reset for a short while. */
	vTaskDelay( tcpRESET_DELAY );

	GPIO_IOCLR = tcpRESET_ACTIVE_HIGH;
	GPIO_IOSET = tcpRESET_ACTIVE_LOW;

	vTaskDelay( tcpINIT_DELAY );

	/* Setup the EINT0 to interrupt on required events from the WIZnet device.
	First enable the EINT0 function of the pin. */
	PCB_PINSEL1 |= tcpENABLE_EINT0_FUNCTION;
	
	/* We want the TCP comms to wake us from power save. */
	SCB_EXTWAKE = tcpWAKE_ON_EINT0;

	/* Install the ISR into the VIC - but don't enable it yet! */
	portENTER_CRITICAL();
	{
		extern void ( vEINT0_ISR_Wrapper )( void );

		VICIntSelect &= ~( tcpEINT0_VIC_CHANNEL_BIT );
		VICVectAddr3 = ( portLONG ) vEINT0_ISR_Wrapper;

		VICVectCntl3 = tcpEINT0_VIC_CHANNEL | tcpEINT0_VIC_ENABLE;
	}
	portEXIT_CRITICAL();

	/* Enable interrupts in the WIZnet itself. */
	i2cMessage( ucDataEnableISR, sizeof( ucDataEnableISR ), tcpDEVICE_ADDRESS, tcpISR_MASK_REG, i2cWRITE, NULL, portMAX_DELAY );

	vTaskDelay( tcpLONG_DELAY );
}
/*-----------------------------------------------------------*/

portLONG lTCPSoftReset( void )
{
unsigned portCHAR ucStatus;
extern volatile portLONG lTransactionCompleted;

	/* Send a message to the WIZnet device to tell it set all it's registers
	back to their default states.  Then setup the WIZnet device as required. */

	/* Reset the internal WIZnet registers. */
	i2cMessage( ucDataReset,	sizeof( ucDataReset ),	tcpDEVICE_ADDRESS, tcpCOMMAND_REG, i2cWRITE, NULL, portMAX_DELAY );

	/* Now we can configure the protocol.   Here the MAC address, gateway 
	address, subnet mask and IP address are configured. */
	i2cMessage( ucDataSHAR,		sizeof( ucDataSHAR ),	tcpDEVICE_ADDRESS, tcpSOURCE_HA_REG, i2cWRITE, NULL, portMAX_DELAY );
	i2cMessage( ucDataGAR,		sizeof( ucDataGAR ),	tcpDEVICE_ADDRESS, tcpGATEWAY_ADDR_REG, i2cWRITE, NULL, portMAX_DELAY );
	i2cMessage( ucDataMSR,		sizeof( ucDataMSR ),	tcpDEVICE_ADDRESS, tcpSUBNET_MASK_REG,	i2cWRITE, NULL, portMAX_DELAY );
	i2cMessage( ucDataSIPR,		sizeof( ucDataSIPR ),	tcpDEVICE_ADDRESS, tpcSOURCE_IP_REG,	i2cWRITE, NULL, portMAX_DELAY );
	
	/* Next the memory buffers are configured to give all the WIZnet internal
	memory over to a single socket.  This gives the socket the maximum internal
	Tx and Rx buffer space. */
	i2cMessage( ucDataSetTxBufSize, sizeof( ucDataSetTxBufSize ), tcpDEVICE_ADDRESS, tcpTX_MEM_SIZE_REG, i2cWRITE, NULL, portMAX_DELAY );
	i2cMessage( ucDataSetRxBufSize, sizeof( ucDataSetRxBufSize ), tcpDEVICE_ADDRESS, tcpRX_MEM_SIZE_REG, i2cWRITE, NULL, portMAX_DELAY );

	/* Send the sys init command so the above parameters take effect. */
	i2cMessage( ucDataInit,		sizeof( ucDataInit ),	tcpDEVICE_ADDRESS, tcpCOMMAND_REG, i2cWRITE, NULL, portMAX_DELAY );

	/* Seems to like a little wait here. */
	vTaskDelay( tcpINIT_DELAY );

	/* Read back the status to ensure the system initialised ok. */
	prvReadRegister( &ucStatus, tcpINTERRUPT_STATUS_REG, tcpSTATUS_READ_LEN );

	/* We should find that the sys init was successful. */
	if( ucStatus != tcpISR_SYS_INIT )
	{
		return ( portLONG ) pdFAIL;
	}

	/* No i2c errors yet. */
	portENTER_CRITICAL();
		lTransactionCompleted = pdTRUE;
	portEXIT_CRITICAL();

	return ( portLONG ) pdPASS;
}
/*-----------------------------------------------------------*/

portLONG lTCPCreateSocket( void )
{
unsigned portCHAR ucStatus;

	/* Create and configure a socket. */

	/* Setup and init the socket.  Here the port number is set and the socket
	is initialised. */
	i2cMessage( ucDataProtocol, sizeof( ucDataProtocol),tcpDEVICE_ADDRESS, tpcSOCKET_OPT_REG, i2cWRITE, NULL, portMAX_DELAY );
	i2cMessage( ucDataPort,		sizeof( ucDataPort),	tcpDEVICE_ADDRESS, tcpSOURCE_PORT_REG, i2cWRITE, NULL, portMAX_DELAY );
	i2cMessage( ucDataSockInit, sizeof( ucDataSockInit),tcpDEVICE_ADDRESS, tcpCOMMAND_REG, i2cWRITE, xMessageComplete, portMAX_DELAY );

	/* Wait for the Init command to be sent. */
	if( !xSemaphoreTake( xMessageComplete, tcpLONG_DELAY ) )
	{
		/* For some reason the message was not transmitted within our block
		period. */
		return ( portLONG ) pdFAIL;
	}

	/* Allow the socket to initialise. */
	vTaskDelay( tcpINIT_DELAY );

	/* Read back the status to ensure the socket initialised ok. */
	prvReadRegister( &ucStatus, tcpINTERRUPT_STATUS_REG, tcpSTATUS_READ_LEN );
	
	/* We should find that the socket init was successful. */
	if( ucStatus != tcpISR_SOCKET_INIT )
	{
		return ( portLONG ) pdFAIL;
	}


	/* Setup the Tx pointer registers to indicate that the Tx buffer is empty. */
	i2cMessage( ucDataTxReadPointer, sizeof( ucDataTxReadPointer ), tcpDEVICE_ADDRESS, tcpTX_READ_POINTER_REG, i2cWRITE, NULL, portMAX_DELAY );
	vTaskDelay( tcpSHORT_DELAY );
	i2cMessage( ucDataTxWritePointer, sizeof( ucDataTxWritePointer ), tcpDEVICE_ADDRESS, tcpTX_WRITE_POINTER_REG, i2cWRITE, NULL, portMAX_DELAY );
	vTaskDelay( tcpSHORT_DELAY );
	i2cMessage( ucDataTxAckPointer,	  sizeof( ucDataTxAckPointer ),	  tcpDEVICE_ADDRESS, tcpTX_ACK_POINTER_REG, i2cWRITE, NULL, portMAX_DELAY );
	vTaskDelay( tcpSHORT_DELAY );

	return ( portLONG ) pdPASS;
}
/*-----------------------------------------------------------*/

void vTCPListen( void )
{
unsigned portCHAR ucISR;

	/* Start a passive listen on the socket. */

	/* Enable interrupts in the WizNet device after ensuring none are 
	currently pending. */
	while( SCB_EXTINT & tcpCLEAR_EINT0 )
	{
		/* The WIZnet device is still asserting and interrupt so tell it to 
		clear. */
		i2cMessage( ucDataClearInterrupt, sizeof( ucDataClearInterrupt ), tcpDEVICE_ADDRESS, tcpINTERRUPT_REG, i2cWRITE, xMessageComplete, portMAX_DELAY );
		xSemaphoreTake( xMessageComplete, tcpLONG_DELAY );

		vTaskDelay( 1 );
		SCB_EXTINT = tcpCLEAR_EINT0;
	}

	while( xQueueReceive( xTCPISRQueue, &ucISR, tcpNO_DELAY ) )
	{
		/* Just clearing the queue used by the ISR routine to tell this task
		that the WIZnet device needs attention. */
	}

	/* Now all the pending interrupts have been cleared we can enable the 
	processor interrupts. */
	VICIntEnable |= tcpEINT0_VIC_CHANNEL_BIT;

	/* Then start listening for incoming connections. */
	i2cMessage( ucDataListen, sizeof( ucDataListen ), tcpDEVICE_ADDRESS, tcpCOMMAND_REG, i2cWRITE, NULL, portMAX_DELAY );
}
/*-----------------------------------------------------------*/

portLONG lProcessConnection( void )
{
unsigned portCHAR ucISR, ucState, ucLastState = 2, ucShadow;
extern volatile portLONG lTransactionCompleted;
portLONG lSameStateCount = 0, lDataSent = pdFALSE;
unsigned portLONG ulWritePointer, ulAckPointer;

	/* No I2C errors can yet have occurred. */
	portENTER_CRITICAL();
		lTransactionCompleted = pdTRUE;
	portEXIT_CRITICAL();

	/* Keep looping - processing interrupts, until we have completed a 
	transaction.   This uses the WIZnet in it's simplest form.  The socket
	accepts a connection - we process the connection - then close the socket.
	We then go back to reinitialise everything and start again. */
	while( lTransactionCompleted == pdTRUE )
	{
		/* Wait for a message on the queue from the WIZnet ISR.  When the 
		WIZnet device asserts an interrupt the ISR simply posts a message
		onto this queue to wake this task. */
		if( xQueueReceive( xTCPISRQueue, &ucISR, tcpCONNECTION_WAIT_DELAY ) )
		{
			/* The ISR posted a message on this queue to tell us that the
			WIZnet device asserted an interrupt.  The ISR cannot process
			an I2C message so cannot tell us what caused the interrupt so
			we have to query the device here.  This task is the highest
			priority in the system so will run immediately following the ISR. */
			prvReadRegister( &ucISR, tcpINTERRUPT_STATUS_REG, tcpSTATUS_READ_LEN );

			/* Once we have read what caused the ISR we can clear the interrupt
			in the WIZnet. */
			i2cMessage( ucDataClearInterrupt, sizeof( ucDataClearInterrupt ), tcpDEVICE_ADDRESS, tcpINTERRUPT_REG, i2cWRITE, NULL, portMAX_DELAY );

			/* Now we can clear the processor interrupt and re-enable ready for
			the next. */
			SCB_EXTINT = tcpCLEAR_EINT0;
			VICIntEnable |= tcpEINT0_VIC_CHANNEL_BIT;
	
			/* Process the interrupt ... */

			if( ucISR & tcpISR_ESTABLISHED )
			{
				/* A connection has been established - respond by sending
				a receive command. */
				i2cMessage( ucDataReceiveCmd, sizeof( ucDataReceiveCmd ), tcpDEVICE_ADDRESS, tcpCOMMAND_REG, i2cWRITE, NULL, portMAX_DELAY );
			}
		
			if( ucISR & tcpISR_RX_COMPLETE )
			{
				/* We message has been received.  This will be an HTTP get 
				command.  We only have one page to send so just send it without
				regard to what the actual requested page was. */
				prvSendSamplePage();
			}
		
		 	if( ucISR & tcpISR_TX_COMPLETE )
			{
				/* We have a TX complete interrupt - which oddly does not 
				indicate that the message being sent is complete so we cannot
				yet close the socket.  Instead we read the position of the Tx
				pointer within the WIZnet device so we know how much data it
				has to send.  Later we will read the ack pointer and compare 
				this to the Tx pointer to ascertain whether the transmission 
				has completed. */

				/* First read the shadow register. */
				prvReadRegister( &ucShadow, tcpTX_WRITE_SHADOW_REG, tcpSHADOW_READ_LEN );
			
				/* Now a short delay is required. */
				vTaskDelay( tcpSHORT_DELAY );

				/* Then we can read the real register. */
				prvReadRegister( ( unsigned portCHAR * ) &ulWritePointer, tcpTX_WRITE_POINTER_REG, sizeof( ulWritePointer ) );

				/* We cannot do anything more here but need to remember that 
				this interrupt has occurred. */
				lDataSent = pdTRUE;
			}
		
			if( ucISR & tcpISR_CLOSED )
			{
				/* The socket has been closed so we can leave this function. */
				lTransactionCompleted = pdFALSE;
			}
		}
		else
		{
			/* We have not received an interrupt from the WIZnet device for a 
			while.  Read the socket status and check that everything is as
			expected. */
			prvReadRegister( &ucState, tcpSOCKET_STATE_REG, tcpSTATUS_READ_LEN );
			
			if( ( ucState == tcpSTATUS_ESTABLISHED ) && ( lDataSent > 0 ) ) 
			{
				/* The socket is established and we have already received a Tx
				end interrupt.  We must therefore be waiting for the Tx buffer
				inside the WIZnet device to be empty before we can close the
				socket. 

				Read the Ack pointer register to see if it has caught up with
				the Tx pointer register.  First we have to read the shadow 
				register. */
				prvReadRegister( &ucShadow, tcpTX_ACK_SHADOW_REG, tcpSHADOW_READ_LEN );
				vTaskDelay( tcpSHORT_DELAY );
				prvReadRegister( ( unsigned portCHAR * ) &ulAckPointer, tcpTX_ACK_POINTER_REG, sizeof( ulWritePointer ) );

				if( ulAckPointer == ulWritePointer )
				{
					/* The Ack and write pointer are now equal and we can 
					safely close the socket. */
					i2cMessage( ucDataDisconnect, sizeof( ucDataDisconnect ), tcpDEVICE_ADDRESS, tcpCOMMAND_REG, i2cWRITE, NULL, portMAX_DELAY );
				}
				else
				{
					/* Keep a count of how many times we encounter the Tx
					buffer still containing data. */
					lDataSent++;
					if( lDataSent > tcpMAX_ATTEMPTS_TO_CHECK_BUFFER )
					{
						/* Assume we cannot complete sending the data and 
						therefore cannot safely close the socket.  Start over. */
						vTCPHardReset();
						lTransactionCompleted = pdFALSE;
					}
				}
			}
			else if( ucState != tcpSTATUS_LISTEN )
			{
				/* If we have not yet received a Tx end interrupt we would only 
				ever expect to find the socket still listening for any 
				sustained period. */
				if( ucState == ucLastState )
				{
					lSameStateCount++;
					if( lSameStateCount > tcpMAX_NON_LISTEN_STAUS_READS )
					{						
						/* We are persistently in an unexpected state.  Assume
						we cannot safely close the socket and start over. */
						vTCPHardReset();
						lTransactionCompleted = pdFALSE;
					}
				}
			}
			else
			{
				/* We are in the listen state so are happy that everything
				is as expected. */
				lSameStateCount = 0;
			}

			/* Remember what state we are in this time around so we can check
			for a persistence on an unexpected state. */
			ucLastState = ucState;
		}
	}

	/* We are going to reinitialise the WIZnet device so do not want our 
	interrupts from the WIZnet to be processed. */
	VICIntEnClear |= tcpEINT0_VIC_CHANNEL_BIT;
	return lTransactionCompleted;
}
/*-----------------------------------------------------------*/

static void prvWriteString( const portCHAR * const pucTxBuffer, portLONG lTxLen, unsigned portLONG *pulTxAddress )
{
unsigned portLONG ulSendAddress;

	/* Send a string to the Tx buffer internal to the WIZnet device. */

	/* Calculate the address to which we are going to write in the buffer. */
	ulSendAddress = ( *pulTxAddress & tcpSINGLE_SOCKET_ADDR_MASK ) + tcpSINGLE_SOCKET_ADDR_OFFSET;

	/* Send the buffer to the calculated address.  Use the semaphore so we
	can wait until the entire message has been transferred. */
	i2cMessage( ( unsigned portCHAR * ) pucTxBuffer, lTxLen, tcpDEVICE_ADDRESS, ( unsigned portSHORT ) ulSendAddress, i2cWRITE, xMessageComplete, portMAX_DELAY );

	/* Wait until the semaphore indicates that the message has been transferred. */
	if( !xSemaphoreTake( xMessageComplete, tcpLONG_DELAY ) )
	{
		return;
	}

	/* Return the new address of the end of the buffer (within the WIZnet 
	device). */
	*pulTxAddress += ( unsigned portLONG ) lTxLen;
}
/*-----------------------------------------------------------*/

static void prvFlushBuffer( unsigned portLONG ulTxAddress )
{
unsigned portCHAR ucTxBuffer[ tcpMAX_REGISTER_LEN ];

	/* We have written some data to the Tx buffer internal to the WIZnet
	device.  Now we update the Tx pointer inside the WIZnet then send a
	Send command - which causes	the data up to the new Tx pointer to be 
	transmitted. */

	/* Make sure endieness is correct for transmission. */
	ulTxAddress = htonl( ulTxAddress );

	/* Place the new Tx pointer in the string to be transmitted. */
	ucTxBuffer[ 0 ] = ( unsigned portCHAR ) ( ulTxAddress & 0xff );
	ulTxAddress >>= 8;
	ucTxBuffer[ 1 ] = ( unsigned portCHAR ) ( ulTxAddress & 0xff );
	ulTxAddress >>= 8;
	ucTxBuffer[ 2 ] = ( unsigned portCHAR ) ( ulTxAddress & 0xff );
	ulTxAddress >>= 8;
	ucTxBuffer[ 3 ] = ( unsigned portCHAR ) ( ulTxAddress & 0xff );
	ulTxAddress >>= 8;

	/* And send it to the WIZnet device. */
	i2cMessage( ucTxBuffer, sizeof( ulTxAddress ), tcpDEVICE_ADDRESS, tcpTX_WRITE_POINTER_REG, i2cWRITE, xMessageComplete, portMAX_DELAY );

	if( !xSemaphoreTake( xMessageComplete, tcpLONG_DELAY ) )
	{
		return;
	}

	vTaskDelay( tcpSHORT_DELAY );

	/* Transmit! */
	i2cMessage( ucDataSend, sizeof( ucDataSend ), tcpDEVICE_ADDRESS, tcpCOMMAND_REG, i2cWRITE, xMessageComplete, portMAX_DELAY );

	if( !xSemaphoreTake( xMessageComplete, tcpLONG_DELAY ) )
	{
		return;
	}
}
/*-----------------------------------------------------------*/

static void prvSendSamplePage( void )
{
extern portLONG lErrorInTask;
unsigned portLONG ulTxAddress;
unsigned portCHAR ucShadow;
portLONG lIndex;
static unsigned portLONG ulRefreshCount = 0x00;
static portCHAR cPageBuffer[ tcpBUFFER_LEN ];


	/* This function just generates a sample page of HTML which gets
	sent each time a client attaches to the socket.  The page is created
	from two fixed strings (cSamplePageFirstPart and cSamplePageSecondPart)
	with a bit of dynamically generated data in the middle. */

	/* We need to know the address to which the html string should be sent
	in the WIZnet Tx buffer.  First read the shadow register. */
	prvReadRegister( &ucShadow, tcpTX_WRITE_SHADOW_REG, tcpSHADOW_READ_LEN );

	/* Now a short delay is required. */
	vTaskDelay( tcpSHORT_DELAY );

	/* Now we can read the real pointer value. */
	prvReadRegister( ( unsigned portCHAR * ) &ulTxAddress, tcpTX_WRITE_POINTER_REG, sizeof( ulTxAddress ) );

	/* Make sure endieness is correct. */
	ulTxAddress = htonl( ulTxAddress );

	/* Send the start of the page. */
	prvWriteString( cSamplePageFirstPart, strlen( cSamplePageFirstPart ), &ulTxAddress );

	/* Generate a bit of dynamic data and place it in the buffer ready to be
	transmitted. */
	strcpy( cPageBuffer, "<BR>Number of ticks since boot = 0x" );
	lIndex = strlen( cPageBuffer );
	ultoa( xTaskGetTickCount(), &( cPageBuffer[ lIndex ] ), 0 );
	strcat( cPageBuffer, "<br>Number of tasks executing = ");
	lIndex = strlen( cPageBuffer );
	ultoa( ( unsigned portLONG ) uxTaskGetNumberOfTasks(), &( cPageBuffer[ lIndex ] ), 0 );
	strcat( cPageBuffer, "<br>IO port 0 state (used by flash tasks) = 0x" );
	lIndex = strlen( cPageBuffer );
	ultoa( ( unsigned portLONG ) GPIO0_IOPIN, &( cPageBuffer[ lIndex ] ), 0 );
	strcat( cPageBuffer, "<br>Refresh = 0x" );
	lIndex = strlen( cPageBuffer );
	ultoa( ( unsigned portLONG ) ulRefreshCount, &( cPageBuffer[ lIndex ] ), 0 );
	
	if( lErrorInTask )
	{
		strcat( cPageBuffer, "<p>An error has occurred in at least one task." );
	}
	else
	{
		strcat( cPageBuffer, "<p>All tasks executing without error." );		
	}

	ulRefreshCount++;

	/* Send the dynamically generated string. */
	prvWriteString( cPageBuffer, strlen( cPageBuffer ), &ulTxAddress );

	/* Finish the page. */
	prvWriteString( cSamplePageSecondPart, strlen( cSamplePageSecondPart ), &ulTxAddress );

	/* Tell the WIZnet to send the data we have just written to its Tx buffer. */
	prvFlushBuffer( ulTxAddress );
}