LXR uboot/arch/x86/cpu/coreboot/ipchecksum.c

   1/*
   2 * This file is part of the libpayload project.
   3 *
   4 * It has originally been taken from the FreeBSD project.
   5 *
   6 * Copyright (c) 2001 Charles Mott <cm@linktel.net>
   7 * Copyright (c) 2008 coresystems GmbH
   8 * All rights reserved.
   9 *
  10 * Redistribution and use in source and binary forms, with or without
  11 * modification, are permitted provided that the following conditions
  12 * are met:
  13 * 1. Redistributions of source code must retain the above copyright
  14 *    notice, this list of conditions and the following disclaimer.
  15 * 2. Redistributions in binary form must reproduce the above copyright
  16 *    notice, this list of conditions and the following disclaimer in the
  17 *    documentation and/or other materials provided with the distribution.
  18 *
  19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29 * SUCH DAMAGE.
  30 */
  31
  32#include <compiler.h>
  33#include <asm/arch-coreboot/ipchecksum.h>
  34
  35unsigned short ipchksum(const void *vptr, unsigned long nbytes)
  36{
  37        int sum, oddbyte;
  38        const unsigned short *ptr = vptr;
  39
  40        sum = 0;
  41        while (nbytes > 1) {
  42                sum += *ptr++;
  43                nbytes -= 2;
  44        }
  45        if (nbytes == 1) {
  46                oddbyte = 0;
  47                ((u8 *)&oddbyte)[0] = *(u8 *) ptr;
  48                ((u8 *)&oddbyte)[1] = 0;
  49                sum += oddbyte;
  50        }
  51        sum = (sum >> 16) + (sum & 0xffff);
  52        sum += (sum >> 16);
  53        return ~sum;
  54}
  55