212 lines
6.5 KiB
C
212 lines
6.5 KiB
C
/* $NetBSD: in_cksum.c,v 1.8 1998/08/15 10:18:17 mycroft Exp $ */
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/*-
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* Copyright (c) 1998 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Charles M. Hannum.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from tahoe: in_cksum.c 1.2 86/01/05
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* @(#)in_cksum.c 1.3 (Berkeley) 1/19/91
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <netinet/in.h>
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/*
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* Checksum routine for Internet Protocol family headers.
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*
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* This routine is very heavily used in the network
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* code and should be modified for each CPU to be as fast as possible.
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*
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* This implementation is the ns32k version.
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*/
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#define REDUCE {sum = (sum & 0xffff) + (sum >> 16);}
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#define ADDCARRY {if (sum > 0xffff) sum -= 0xffff;}
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#define SWAP {sum <<= 8;}
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#define ADVANCE(x) {w += x; mlen -= x;}
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/*
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* Thanks to gcc we don't have to guess
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* which registers contain sum & w.
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*/
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#define Asm __asm __volatile
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#define ADD(n) Asm("addd " #n "(%2),%0" : "=r" (sum) : "0" (sum), "r" (w))
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#define ADC(n) Asm("addcd " #n "(%2),%0" : "=r" (sum) : "0" (sum), "r" (w))
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#define MOP Asm("addcd 0,%0" : "=r" (sum) : "0" (sum))
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#define UNSWAP Asm("rotd 8,%0" : "=r" (sum) : "0" (sum))
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#define ADDBYTE {sum += *w; SWAP; byte_swapped ^= 1;}
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#define ADDWORD {sum += *(u_short *)w;}
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int
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in_cksum(m, len)
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register struct mbuf *m;
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register int len;
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{
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register u_char *w;
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register unsigned sum = 0;
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register int mlen = 0;
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int byte_swapped = 0;
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for (; m && len; m = m->m_next) {
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mlen = m->m_len;
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if (mlen == 0)
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continue;
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w = mtod(m, u_char *);
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if (len < mlen)
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mlen = len;
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len -= mlen;
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if (mlen < 16)
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goto short_mbuf;
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/*
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* Force to long boundary so we do longword aligned
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* memory operations
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*/
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if ((3 & (long)w) != 0) {
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REDUCE;
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if ((1 & (long)w) != 0) {
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ADDBYTE;
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ADVANCE(1);
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}
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if ((2 & (long)w) != 0) {
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ADDWORD;
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ADVANCE(2);
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}
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}
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/*
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* Align 4 bytes past a 16-byte cache line boundary.
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*/
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if ((4 & (long)w) == 0) {
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ADD(0);
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MOP;
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ADVANCE(4);
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}
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if ((8 & (long)w) != 0) {
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ADD(0); ADC(4);
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MOP;
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ADVANCE(8);
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}
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/*
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* Do as much of the checksum as possible 32 bits at at time.
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* In fact, this loop is unrolled to make overhead from
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* branches &c small.
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*/
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while (mlen >= 32) {
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/*
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* Add with carry 16 words and fold in the last carry
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* by adding a 0 with carry.
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*
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* Use the burst fill delay for pointer update.
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*/
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ADD(0); ADC(4); ADC(8); ADC(12);
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MOP;
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w += 32;
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ADD(-16); ADC(-12); ADC(-8); ADC(-4);
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MOP;
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mlen -= 32;
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}
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if (mlen >= 16) {
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ADD(12); ADC(0); ADC(4); ADC(8);
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MOP;
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ADVANCE(16);
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}
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short_mbuf:
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if (mlen >= 8) {
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ADD(0); ADC(4);
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MOP;
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ADVANCE(8);
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}
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if (mlen >= 4) {
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ADD(0);
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MOP;
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ADVANCE(4);
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}
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if (mlen > 0) {
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REDUCE;
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if (mlen >= 2) {
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ADDWORD;
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ADVANCE(2);
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}
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if (mlen >= 1) {
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ADDBYTE;
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}
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}
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}
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if (len)
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printf("cksum: out of data\n");
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if (byte_swapped) {
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UNSWAP;
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}
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REDUCE;
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ADDCARRY;
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return (sum ^ 0xffff);
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}
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