f66e235a13
guru out there can find a way to take advantage of little-endianness to make this computation more efficient. (I am certain that it can be done, but haven't managed to make it work myself.)
93 lines
3.2 KiB
C
93 lines
3.2 KiB
C
/*-
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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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* from: @(#)in_cksum.c 1.3 (Berkeley) 1/19/91
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* from: Id: in_cksum.c,v 1.8 1995/12/03 18:35:19 bde Exp
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* $Id: in_cksum.h,v 1.1 1996/04/18 15:39:27 wollman Exp $
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*/
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#ifndef _MACHINE_IN_CKSUM_H_
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#define _MACHINE_IN_CKSUM_H_ 1
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#include <sys/cdefs.h>
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/*
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* It it useful to have an Internet checksum routine which is inlineable
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* and optimized specifically for the task of computing IP header checksums
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* in the normal case (where there are no options and the header length is
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* therefore always exactly five 32-bit words.
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*/
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#ifdef __GNUC__
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static __inline u_int
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in_cksum_hdr(const struct ip *ip)
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{
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register u_int sum = 0;
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#define ADD(n) __asm("addl " #n "(%2), %0" : "=r" (sum) : "0" (sum), "r" (ip))
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#define ADDC(n) __asm("adcl " #n "(%2), %0" : "=r" (sum) : "0" (sum), "r" (ip))
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#define MOP __asm("adcl $0, %0" : "=r" (sum) : "0" (sum))
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ADD(0);
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ADDC(4);
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ADDC(8);
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ADDC(12);
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ADDC(16);
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MOP;
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sum = (sum & 0xffff) + (sum >> 16);
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if (sum > 0xffff)
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sum -= 0xffff;
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return ~sum & 0xffff;
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}
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static __inline void
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in_cksum_update(struct ip *ip)
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{
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int __tmpsum;
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__tmpsum = (int)ntohs(ip->ip_sum) + 256;
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ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16));
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}
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#else
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u_int in_cksum_hdr __P((const struct ip *));
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#define in_cksum_update(ip) \
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do { \
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int __tmpsum; \
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__tmpsum = (int)ntohs(ip->ip_sum) + 256; \
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ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16)); \
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} while(0)
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#endif
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#endif /* _MACHINE_IN_CKSUM_H_ */
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