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/*

 * Copyright (c) 2004, Swedish Institute of Computer Science.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the name of the Institute nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * This file is part of the uIP TCP/IP stack

 *

 * Author: Adam Dunkels <adam@sics.se>

 *

 * $Id: uip-split.c 2 2011-07-17 20:13:17Z filepang@gmail.com $

 */

#include <string.h>

#include "uip-split.h"

#include "uip.h"

#include "uip-fw.h"

#include "uip_arch.h"

#define BUF ( ( struct uip_tcpip_hdr * ) &uip_buf[UIP_LLH_LEN] )

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

void uip_split_output( void )

{

        u16_t   tcplen, len1, len2;

        /* We only try to split maximum sized TCP segments. */

        if( BUF->proto == UIP_PROTO_TCP && uip_len == UIP_BUFSIZE - UIP_LLH_LEN )

        {

                tcplen = uip_len - UIP_TCPIP_HLEN;

                /* Split the segment in two. If the original packet length was

       odd, we make the second packet one byte larger. */

                len1 = len2 = tcplen / 2;

                if( len1 + len2 < tcplen )

                {

                        ++len2;

                }

                /* Create the first packet. This is done by altering the length

       field of the IP header and updating the checksums. */

                uip_len = len1 + UIP_TCPIP_HLEN;

                #if UIP_CONF_IPV6

                /* For IPv6, the IP length field does not include the IPv6 IP header

       length. */

                BUF->len[0] = ( (uip_len - UIP_IPH_LEN) >> 8 );

                BUF->len[1] = ( (uip_len - UIP_IPH_LEN) & 0xff );

                #else /* UIP_CONF_IPV6 */

                BUF->len[0] = uip_len >> 8;

                BUF->len[1] = uip_len & 0xff;

                #endif /* UIP_CONF_IPV6 */

                /* Recalculate the TCP checksum. */

                BUF->tcpchksum = 0;

                BUF->tcpchksum = ~( uip_tcpchksum() );

                #if !UIP_CONF_IPV6

                /* Recalculate the IP checksum. */

                BUF->ipchksum = 0;

                BUF->ipchksum = ~( uip_ipchksum() );

                #endif /* UIP_CONF_IPV6 */

                /* Transmit the first packet. */

                /*    uip_fw_output();*/

                //    tcpip_output();

                /* Now, create the second packet. To do this, it is not enough to

       just alter the length field, but we must also update the TCP

       sequence number and point the uip_appdata to a new place in

       memory. This place is detemined by the length of the first

       packet (len1). */

                uip_len = len2 + UIP_TCPIP_HLEN;

                #if UIP_CONF_IPV6

                /* For IPv6, the IP length field does not include the IPv6 IP header

       length. */

                BUF->len[0] = ( (uip_len - UIP_IPH_LEN) >> 8 );

                BUF->len[1] = ( (uip_len - UIP_IPH_LEN) & 0xff );

                #else /* UIP_CONF_IPV6 */

                BUF->len[0] = uip_len >> 8;

                BUF->len[1] = uip_len & 0xff;

                #endif /* UIP_CONF_IPV6 */

                /*    uip_appdata += len1;*/

                memcpy( uip_appdata, ( u8_t * ) uip_appdata + len1, len2 );

                uip_add32( BUF->seqno, len1 );

                BUF->seqno[0] = uip_acc32[0];

                BUF->seqno[1] = uip_acc32[1];

                BUF->seqno[2] = uip_acc32[2];

                BUF->seqno[3] = uip_acc32[3];

                /* Recalculate the TCP checksum. */

                BUF->tcpchksum = 0;

                BUF->tcpchksum = ~( uip_tcpchksum() );

                #if !UIP_CONF_IPV6

                /* Recalculate the IP checksum. */

                BUF->ipchksum = 0;

                BUF->ipchksum = ~( uip_ipchksum() );

                #endif /* UIP_CONF_IPV6 */

                /* Transmit the second packet. */

                /*    uip_fw_output();*/

                //    tcpip_output();

        }

        else

        {

                /*    uip_fw_output();*/

                //    tcpip_output();

        }

}

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