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//==========================================================================

//

//      net/cksum.c

//

//      Stand-alone network checksum support for RedBoot

//

//==========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

// Software Foundation; either version 2 or (at your option) any later version.

//

// eCos 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 eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

//

// This exception does not invalidate any other reasons why a work based on

// this file might be covered by the GNU General Public License.

//

// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

// -------------------------------------------

//####ECOSGPLCOPYRIGHTEND####

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):    gthomas

// Contributors: gthomas

// Date:         2000-07-14

// Purpose:      

// Description:  

//              

// This code is part of RedBoot (tm).

//

//####DESCRIPTIONEND####

//

//==========================================================================

#include <net/net.h>

/*

 * Do a one's complement checksum.

 * The data being checksum'd is in network byte order.

 * The returned checksum is in network byte order.

 */

unsigned short

__sum(word *w, int len, int init_sum)

{

    int sum = init_sum;

    union {

        volatile unsigned char c[2];

        volatile unsigned short s;

    } su;

    union {

        volatile unsigned short s[2];

        volatile int i;

    } iu;

    while ((len -= 2) >= 0)

        sum += *w++;

    if (len == -1) {

        su.c[0] = *(char *)w;

        su.c[1] = 0;

        sum += su.s;

    }

    iu.i = sum;

    sum = iu.s[0] + iu.s[1];

    if (sum > 65535)

        sum -= 65535;

    su.s = ~sum;

    return (su.c[0] << 8) | su.c[1];

}

/*

 * Compute a partial checksum for the UDP/TCP pseudo header.

 */

int

__pseudo_sum(ip_header_t *ip)

{

    int    sum;

    word   *p;

    union {

        volatile unsigned char c[2];

        volatile unsigned short s;

    } su;

    p = (word *)ip->source;

    sum  = *p++;

    sum += *p++;

    sum += *p++;

    sum += *p++;

    su.c[0] = 0;

    su.c[1] = ip->protocol;

    sum += su.s;

    sum += ip->length;

    return sum;

}