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[/] [openrisc/] [trunk/] [rtos/] [ecos-2.0/] [packages/] [redboot/] [v2_0/] [src/] [net/] [cksum.c] - Rev 256
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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; }
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