//##############################################################
//#
//# TCP_IP.C
//#
//# ADSP-21535 Embedded Web Server Project
//#
//# (c) ANALOG DEVICES 2002
//#     eDSP Division
//#     Stefan Hacker
//#     28-DEC-2002
//#
//#     framework by Andreas Dannenberg (adannenb@et.htwk-leipzig.de)
//#
//# History:
//#     28-DEC-2002 initial document
//#     03-JAN-2003 ping works properly
//#     31-MAR-2003 fixed FIN bug for OPERA
//#     16-APR-2003 HS  release 1.0
//#

#include "tcp_ip.h"
#include "globals.h"
#include "defBF533.h"
#include "string.h"
#include "ez_lan_types.h"

#define MC section("L1_code")

/******************************************************************************
 * TCP_IP_STACK: TCP_init()
 *
 * Purpose:
 *  initializes the TCP State Machine
 *
 * Actions:
 *  - set State to CLOSED
 *  - set Socket Status
 *  - set Transmit Control
 *  - set TCP_Flags
 *
 *****************************************************************************/
MC void TCP_init()
{
    TCP_StateMachine = CLOSED;
    TCP_TransmitControl = 0;
    TCP_Flags = 0;
    TCP_SocketStatus = 0;
}


/******************************************************************************
 * TCP_IP_STACK: TCP_PassiveOpen()
 *
 * Purpose:
 *  starts listening for an incoming connection if previously closed
 *
 * Actions:
 *
 *****************************************************************************/
MC void TCP_PassiveOpen(void)
{
    if (TCP_StateMachine == CLOSED)
    {
        // let's do a passive open
        TCP_Flags &= ~TCP_ACTIVE_OPEN;
        TCP_StateMachine = LISTENING;

        // reset, socket now active
        TCP_SocketStatus = TCP_SOCK_ACTIVE;
    }
}

/******************************************************************************
 * TCP_IP_STACK: TCP_ActiveOpen()
 *
 * Purpose:
 *  does an active open = tries to establish a connection between
 *   'Local_IP:TCP_LocalPort' and 'TCP_RemoteIP:TCP_RemotePort'
 *
 * Actions:
 *
 *****************************************************************************/
MC void TCP_ActiveOpen()
{
    if ((TCP_StateMachine == CLOSED) || (TCP_StateMachine == LISTENING))
    {
        // let's do an active open
        TCP_Flags |= TCP_ACTIVE_OPEN;

        // we haven't Remote MAC yet
        TCP_Flags &= ~TCP_IP_ADDR_RESOLVED;

        // ask for MAC by sending a broadcast
        TCP_Prep_ARP_REQUEST();

        TCP_LastFrameSent = ARP_REQUEST;
        TCP_StartRetryTimer();

        // reset, socket now active
        TCP_SocketStatus = TCP_SOCK_ACTIVE;
    }
}


/******************************************************************************
 * TCP_IP_STACK: TCP_Close()
 *
 * Purpose:
 *  closes an open connection
 *
 * Actions:
 *
 *****************************************************************************/
MC void TCP_Close()
{
    switch (TCP_StateMachine)
    {
        case LISTENING :
        case SYN_SENT :
        {
            // no connection, we can close right now
            TCP_StateMachine = CLOSED;
            TCP_Flags = 0;
            TCP_SocketStatus = 0;
            break;
        }
        case SYN_RECD :
        case ESTABLISHED :
        {
            // request closing of stack
            TCP_Flags |= TCP_CLOSE_REQUESTED;
            break;
        }
    }
}


/******************************************************************************
 * TCP_IP_STACK: TCP_ReleaseRxBuffer()
 *
 * Purpose:
 *  releases the receive-buffer and allow to store new data
 *
 * Actions:
 *
 *****************************************************************************/
MC void TCP_ReleaseRxBuffer()
{
    // flag buffer available
    TCP_SocketStatus &= ~TCP_SOCK_DATA_AVAILABLE;
}


/******************************************************************************
 * TCP_IP_STACK: TCP_TransmitTxBuffer()
 *
 * Purpose:
 *  transmitts data stored in 'TCP_TX_BUF'
 *
 * Actions:
 *
 * Comments:
 *  number of bytes to transmit must have been written to 'TCPTxDataCount'
 *  data-count MUST NOT exceed 'MAX_TCP_TX_SIZE'
 *
 *****************************************************************************/
MC void TCP_TransmitTxBuffer()
{
    if ((TCP_StateMachine == ESTABLISHED) || (TCP_StateMachine == CLOSE_WAIT))
        if (TCP_SocketStatus & TCP_SOCK_TX_BUF_RELEASED)
        {
            // free tx-buffer
            TCP_SocketStatus &= ~TCP_SOCK_TX_BUF_RELEASED;
            // advance UNA
            TCP_UNA_Seq_Nr += TCP_Tx_Data_Count;

            TCP_TxFrame1Size = TCP_Tx_Data_Count + ETH_HEADER_SIZE + IP_HEADER_SIZE + TCP_HEADER_SIZE;
            TCP_TransmitControl |= TCP_SEND_FRAME1;

            TCP_LastFrameSent = TCP_DATA_FRAME;

            // see how ofen we need to resend
            TCP_StartRetryTimer();
        }
}


/******************************************************************************
 * TCP_IP_STACK: TCP_StateMachine()
 *
 * Purpose:
 *  The TCP/IP statemachine.
 *
 * Note:
 *  Must be run, even if now new data is present, as status can update
 *  due to timeouts, too.
 *
 * Actions:
 *
 *****************************************************************************/
MC void TCP_State_Machine()
{
    WORD *data = (WORD*) LAN_rx_packet.data;

    // process LAN only if new data is available
    if (LAN_rx_packet.busy)
    {
        // check for received frame type by XOR:
        //   either IA (individual address) or broadcast
        if ((*data++ ^ *data++ ^ *data++) != 0xffff)
            TCP_Proc_EthIA_Frame();
        else
            TCP_Proc_EthBroadcast_Frame();
    }

    // update TCP_StateMachine accordingly
    if (TCP_Flags & TCP_TIMER_RUNNING)
        if (TCP_Flags & TCP_TIMER_TYPE_RETRY)
        {
            if (TCP_Timer > TCP_RETRY_TIMEOUT)
            {
                // set a new timeout
                TCP_RestartTimer();

                // check RetryCounter
                if (TCP_RetryCounter)
                {
                    // resend last frame
                    TCP_HandleRetransmission();
                    TCP_RetryCounter--;
                }
                else
                {
                    TCP_StopTimer();
                    TCP_HandleTimeout();
                }
            }
        }
        else if (TCP_Timer > TCP_FIN_TIMEOUT)
        {
            // reset all flags, stop retransmission...
            TCP_StateMachine = CLOSED;
            TCP_Flags = 0;
            // clear all flags but data available
            TCP_SocketStatus &= TCP_SOCK_DATA_AVAILABLE;
        }

    switch (TCP_StateMachine)
    {
        case CLOSED :
        case LISTENING :
        {
            // stack has to open a connection?
            if (TCP_Flags & TCP_ACTIVE_OPEN)

                // IP resolved?
                if (TCP_Flags & TCP_IP_ADDR_RESOLVED)

                    // buffer free?
                    if (!(TCP_TransmitControl & TCP_SEND_FRAME2))
                    {
                        // set local ISN
                        TCP_Seq_Nr = ((TCP_ISN_Gen_High << 16) | get_cycles());
                        TCP_UNA_Seq_Nr = TCP_Seq_Nr;

                        // we don't know what to ACK yet
                        TCP_Ack_Nr = 0;

                        // count SYN as a byte
                        TCP_UNA_Seq_Nr++;

                        // send SYN frame
                        TCP_Prep_TCP_FRAME(TCP_CODE_SYN);
                        TCP_LastFrameSent = TCP_SYN_FRAME;

                        // we NEED a retry-timeout
                        TCP_StartRetryTimer();
                        TCP_StateMachine = SYN_SENT;
                    }
            break;
        }
        case SYN_RECD :
        case ESTABLISHED :
        {
            // user has user initated a close?
            if (TCP_Flags & TCP_CLOSE_REQUESTED)

                // buffers free?
                if (!(TCP_TransmitControl & (TCP_SEND_FRAME2 | TCP_SEND_FRAME1)))

                    // all data ACKed?
                    if (TCP_Seq_Nr == TCP_UNA_Seq_Nr)
                    {
                        TCP_UNA_Seq_Nr++;
                        TCP_Prep_TCP_FRAME(TCP_CODE_FIN | TCP_CODE_ACK);
                        TCP_LastFrameSent = TCP_FIN_FRAME;
                        TCP_StartRetryTimer();
                        TCP_StateMachine = FIN_WAIT_1;
                    }
            break;
        }
        case CLOSE_WAIT :
        {
            // buffers free?
            if (!(TCP_TransmitControl & (TCP_SEND_FRAME2 | TCP_SEND_FRAME1)))

                // all data ACKed?
                if (TCP_Seq_Nr == TCP_UNA_Seq_Nr)
                {
                    // count FIN as a byte
                    TCP_UNA_Seq_Nr++;

                    // we NEED a retry-timeout
                    TCP_Prep_TCP_FRAME(TCP_CODE_FIN | TCP_CODE_ACK);

                    // time to say goodbye...
                    TCP_LastFrameSent = TCP_FIN_FRAME;
                    TCP_StartRetryTimer();
                    TCP_StateMachine = LAST_ACK;
                }
            break;
        }
    }
    if (TCP_TransmitControl & TCP_SEND_FRAME2)
    {
        // copy TX_Buffer to LAN_tx_packet.data
        TCP_Copy_Frame(TCP_TxFrame2Size, TCP_TxFrame2);

        // allocate packet memory;
        smc_allocate_packet();

        // wait for allocation or flag error
        if(LAN_state.alloc_success)
        {
            smc_hardware_send_packet();
        }
        else
        {
            TCP_StateMachine = CLOSED;

            // indicate an error to user
            TCP_SocketStatus = TCP_SOCK_ERR_ETHERNET;

            // clear all flags, stop timers etc.
            TCP_Flags = 0;
        }
        // clear tx-flag
        TCP_TransmitControl &= ~TCP_SEND_FRAME2;
    }

    if (TCP_TransmitControl & TCP_SEND_FRAME1)
    {
        // build frame w/ actual SEQ, ACK....
        TCP_Prep_TCP_DATA_FRAME();
        TCP_Copy_Frame(TCP_TxFrame1Size, TCP_TxFrame1);

        // allocate packet memory on LAN controller;
        smc_allocate_packet();

        // wait for allocation or flag error
        if(LAN_state.alloc_success)
        {
            smc_hardware_send_packet();
        }
        else
        {
            TCP_StateMachine = CLOSED;
            
            // indicate an error to user
            TCP_SocketStatus = TCP_SOCK_ERR_ETHERNET;