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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 Free Software Foundation, 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.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 v2.
//
// This exception does not invalidate any other reasons why a work based
// on this file might be covered by the GNU General Public 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;
}
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