1*4a5d661aSToomas Soome /* $NetBSD: in_cksum.c,v 1.6 2000/03/31 19:55:09 castor Exp $ */ 2*4a5d661aSToomas Soome 3*4a5d661aSToomas Soome /* 4*4a5d661aSToomas Soome * Copyright (c) 1992 Regents of the University of California. 5*4a5d661aSToomas Soome * All rights reserved. 6*4a5d661aSToomas Soome * 7*4a5d661aSToomas Soome * This software was developed by the Computer Systems Engineering group 8*4a5d661aSToomas Soome * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 9*4a5d661aSToomas Soome * contributed to Berkeley. 10*4a5d661aSToomas Soome * 11*4a5d661aSToomas Soome * Redistribution and use in source and binary forms, with or without 12*4a5d661aSToomas Soome * modification, are permitted provided that the following conditions 13*4a5d661aSToomas Soome * are met: 14*4a5d661aSToomas Soome * 1. Redistributions of source code must retain the above copyright 15*4a5d661aSToomas Soome * notice, this list of conditions and the following disclaimer. 16*4a5d661aSToomas Soome * 2. Redistributions in binary form must reproduce the above copyright 17*4a5d661aSToomas Soome * notice, this list of conditions and the following disclaimer in the 18*4a5d661aSToomas Soome * documentation and/or other materials provided with the distribution. 19*4a5d661aSToomas Soome * 4. Neither the name of the University nor the names of its contributors 20*4a5d661aSToomas Soome * may be used to endorse or promote products derived from this software 21*4a5d661aSToomas Soome * without specific prior written permission. 22*4a5d661aSToomas Soome * 23*4a5d661aSToomas Soome * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24*4a5d661aSToomas Soome * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25*4a5d661aSToomas Soome * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26*4a5d661aSToomas Soome * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27*4a5d661aSToomas Soome * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28*4a5d661aSToomas Soome * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29*4a5d661aSToomas Soome * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30*4a5d661aSToomas Soome * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31*4a5d661aSToomas Soome * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32*4a5d661aSToomas Soome * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33*4a5d661aSToomas Soome * SUCH DAMAGE. 34*4a5d661aSToomas Soome * 35*4a5d661aSToomas Soome * @(#) Header: in_cksum.c,v 1.1 92/09/11 01:15:55 leres Exp (LBL) 36*4a5d661aSToomas Soome */ 37*4a5d661aSToomas Soome 38*4a5d661aSToomas Soome #include <sys/cdefs.h> 39*4a5d661aSToomas Soome __FBSDID("$FreeBSD$"); 40*4a5d661aSToomas Soome 41*4a5d661aSToomas Soome #include <sys/types.h> 42*4a5d661aSToomas Soome #include <machine/endian.h> 43*4a5d661aSToomas Soome 44*4a5d661aSToomas Soome #include "stand.h" 45*4a5d661aSToomas Soome 46*4a5d661aSToomas Soome /* 47*4a5d661aSToomas Soome * Checksum routine for Internet Protocol family headers. 48*4a5d661aSToomas Soome * This routine is very heavily used in the network 49*4a5d661aSToomas Soome * code and should be modified for each CPU to be as fast as possible. 50*4a5d661aSToomas Soome * In particular, it should not be this one. 51*4a5d661aSToomas Soome */ 52*4a5d661aSToomas Soome int 53*4a5d661aSToomas Soome in_cksum(p, len) 54*4a5d661aSToomas Soome void *p; 55*4a5d661aSToomas Soome int len; 56*4a5d661aSToomas Soome { 57*4a5d661aSToomas Soome int sum = 0, oddbyte = 0, v = 0; 58*4a5d661aSToomas Soome u_char *cp = p; 59*4a5d661aSToomas Soome 60*4a5d661aSToomas Soome /* we assume < 2^16 bytes being summed */ 61*4a5d661aSToomas Soome while (len > 0) { 62*4a5d661aSToomas Soome if (oddbyte) { 63*4a5d661aSToomas Soome sum += v + *cp++; 64*4a5d661aSToomas Soome len--; 65*4a5d661aSToomas Soome } 66*4a5d661aSToomas Soome if (((long)cp & 1) == 0) { 67*4a5d661aSToomas Soome while ((len -= 2) >= 0) { 68*4a5d661aSToomas Soome sum += *(u_short *)cp; 69*4a5d661aSToomas Soome cp += 2; 70*4a5d661aSToomas Soome } 71*4a5d661aSToomas Soome } else { 72*4a5d661aSToomas Soome while ((len -= 2) >= 0) { 73*4a5d661aSToomas Soome #if BYTE_ORDER == BIG_ENDIAN 74*4a5d661aSToomas Soome sum += *cp++ << 8; 75*4a5d661aSToomas Soome sum += *cp++; 76*4a5d661aSToomas Soome #else 77*4a5d661aSToomas Soome sum += *cp++; 78*4a5d661aSToomas Soome sum += *cp++ << 8; 79*4a5d661aSToomas Soome #endif 80*4a5d661aSToomas Soome } 81*4a5d661aSToomas Soome } 82*4a5d661aSToomas Soome if ((oddbyte = len & 1) != 0) 83*4a5d661aSToomas Soome #if BYTE_ORDER == BIG_ENDIAN 84*4a5d661aSToomas Soome v = *cp << 8; 85*4a5d661aSToomas Soome #else 86*4a5d661aSToomas Soome v = *cp; 87*4a5d661aSToomas Soome #endif 88*4a5d661aSToomas Soome } 89*4a5d661aSToomas Soome if (oddbyte) 90*4a5d661aSToomas Soome sum += v; 91*4a5d661aSToomas Soome sum = (sum >> 16) + (sum & 0xffff); /* add in accumulated carries */ 92*4a5d661aSToomas Soome sum += sum >> 16; /* add potential last carry */ 93*4a5d661aSToomas Soome return (0xffff & ~sum); 94*4a5d661aSToomas Soome } 95