53 lines
1.4 KiB
C++
53 lines
1.4 KiB
C++
/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
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/*
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* Copyright (c) 2005,2006,2007 INRIA
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation;
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
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*/
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#include "ipv4-checksum.h"
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namespace ns3 {
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uint16_t
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Ipv4ChecksumCalculate (uint16_t checksum, uint8_t *buffer, uint16_t size)
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{
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/* see RFC 1071 to understand this code. */
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uint32_t sum = checksum;
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uint16_t *data = (uint16_t *) buffer;
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for (uint16_t i = 0; i < (size/2); i++) {
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sum += data[i];
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}
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if ((size % 2) != 0) {
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uint8_t tmpBuf[2];
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tmpBuf[0] = buffer[size-1];
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tmpBuf[1] = 0;
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data = (uint16_t *)tmpBuf;
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sum += *data;
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}
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while (sum >> 16) {
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sum = (sum & 0xffff) + (sum >> 16);
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}
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return sum;
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}
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uint16_t
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Ipv4ChecksumComplete (uint16_t checksum)
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{
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return ~checksum;
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}
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}; //namespace ns3
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