FreeRTOS-RISCV/FreeRTOSv10.2.1/FreeRTOS/Demo/Common/ethernet/FreeRTOS-uIP/uip-split.c

/*
 * 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,v 1.2 2006/06/12 08:00:30 adam Exp $
 */
#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();
	}
}

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