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https://github.com/freebsd/freebsd-src
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205 lines
6.4 KiB
C
205 lines
6.4 KiB
C
/*
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* Copyright (c) 1982, 1992, 1993
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* The Regents of the University of California. 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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* @(#)ns_cksum.c 8.1 (Berkeley) 6/10/93
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* $Id$
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*/
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#include <sys/param.h>
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#include <sys/mbuf.h>
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/*
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* Checksum routine for Network Systems Protocol Packets (Big-Endian).
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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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#define ADDCARRY(x) { if ((x) > 65535) (x) -= 65535; }
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#define FOLD(x) {l_util.l = (x); (x) = l_util.s[0] + l_util.s[1]; ADDCARRY(x);}
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u_short
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ns_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_short *w;
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register int sum = 0;
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register int mlen = 0;
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register int sum2;
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union {
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u_short s[2];
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long l;
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} l_util;
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for (;m && len; m = m->m_next) {
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if (m->m_len == 0)
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continue;
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/*
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* Each trip around loop adds in
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* word from one mbuf segment.
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*/
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w = mtod(m, u_short *);
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if (mlen == -1) {
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/*
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* There is a byte left from the last segment;
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* ones-complement add it into the checksum.
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*/
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#if BYTE_ORDER == BIG_ENDIAN
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sum += *(u_char *)w;
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#else
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sum += *(u_char *)w << 8;
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#endif
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sum += sum;
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w = (u_short *)(1 + (char *)w);
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mlen = m->m_len - 1;
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len--;
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FOLD(sum);
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} else
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mlen = m->m_len;
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if (len < mlen)
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mlen = len;
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len -= mlen;
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/*
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* We can do a 16 bit ones complement sum using
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* 32 bit arithmetic registers for adding,
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* with carries from the low added
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* into the high (by normal carry-chaining)
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* so long as we fold back before 16 carries have occured.
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*/
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if (1 & (int) w)
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goto uuuuglyy;
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#ifndef TINY
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/* -DTINY reduces the size from 1250 to 550, but slows it down by 22% */
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while ((mlen -= 32) >= 0) {
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sum += w[0]; sum += sum; sum += w[1]; sum += sum;
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sum += w[2]; sum += sum; sum += w[3]; sum += sum;
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sum += w[4]; sum += sum; sum += w[5]; sum += sum;
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sum += w[6]; sum += sum; sum += w[7]; sum += sum;
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FOLD(sum);
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sum += w[8]; sum += sum; sum += w[9]; sum += sum;
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sum += w[10]; sum += sum; sum += w[11]; sum += sum;
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sum += w[12]; sum += sum; sum += w[13]; sum += sum;
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sum += w[14]; sum += sum; sum += w[15]; sum += sum;
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FOLD(sum);
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w += 16;
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}
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mlen += 32;
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#endif
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while ((mlen -= 8) >= 0) {
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sum += w[0]; sum += sum; sum += w[1]; sum += sum;
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sum += w[2]; sum += sum; sum += w[3]; sum += sum;
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FOLD(sum);
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w += 4;
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}
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mlen += 8;
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while ((mlen -= 2) >= 0) {
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sum += *w++; sum += sum;
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}
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goto commoncase;
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uuuuglyy:
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#if BYTE_ORDER == BIG_ENDIAN
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#define ww(n) (((u_char *)w)[n + n + 1])
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#define vv(n) (((u_char *)w)[n + n])
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#else
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#if BYTE_ORDER == LITTLE_ENDIAN
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#define vv(n) (((u_char *)w)[n + n + 1])
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#define ww(n) (((u_char *)w)[n + n])
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#endif
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#endif
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sum2 = 0;
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#ifndef TINY
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while ((mlen -= 32) >= 0) {
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sum += ww(0); sum += sum; sum += ww(1); sum += sum;
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sum += ww(2); sum += sum; sum += ww(3); sum += sum;
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sum += ww(4); sum += sum; sum += ww(5); sum += sum;
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sum += ww(6); sum += sum; sum += ww(7); sum += sum;
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FOLD(sum);
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sum += ww(8); sum += sum; sum += ww(9); sum += sum;
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sum += ww(10); sum += sum; sum += ww(11); sum += sum;
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sum += ww(12); sum += sum; sum += ww(13); sum += sum;
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sum += ww(14); sum += sum; sum += ww(15); sum += sum;
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FOLD(sum);
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sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
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sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
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sum2 += vv(4); sum2 += sum2; sum2 += vv(5); sum2 += sum2;
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sum2 += vv(6); sum2 += sum2; sum2 += vv(7); sum2 += sum2;
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FOLD(sum2);
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sum2 += vv(8); sum2 += sum2; sum2 += vv(9); sum2 += sum2;
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sum2 += vv(10); sum2 += sum2; sum2 += vv(11); sum2 += sum2;
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sum2 += vv(12); sum2 += sum2; sum2 += vv(13); sum2 += sum2;
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sum2 += vv(14); sum2 += sum2; sum2 += vv(15); sum2 += sum2;
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FOLD(sum2);
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w += 16;
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}
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mlen += 32;
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#endif
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while ((mlen -= 8) >= 0) {
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sum += ww(0); sum += sum; sum += ww(1); sum += sum;
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sum += ww(2); sum += sum; sum += ww(3); sum += sum;
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FOLD(sum);
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sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
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sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
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FOLD(sum2);
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w += 4;
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}
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mlen += 8;
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while ((mlen -= 2) >= 0) {
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sum += ww(0); sum += sum;
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sum2 += vv(0); sum2 += sum2;
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w++;
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}
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sum += (sum2 << 8);
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commoncase:
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if (mlen == -1) {
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#if BYTE_ORDER == BIG_ENDIAN
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sum += *(u_char *)w << 8;
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#else
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sum += *(u_char *)w;
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#endif
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}
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FOLD(sum);
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}
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if (mlen == -1) {
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/* We had an odd number of bytes to sum; assume a garbage
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byte of zero and clean up */
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sum += sum;
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FOLD(sum);
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}
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/*
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* sum has already been kept to low sixteen bits.
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* just examine result and exit.
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*/
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if(sum==0xffff) sum = 0;
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return (sum);
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}
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