1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright (c) 1996-2001 by Sun Microsystems, Inc. 24 * All rights reserved. 25 */ 26 27 #include <sys/types.h> 28 #include "v4_sum_impl.h" 29 30 /* 31 * Compute one's complement checksum for IP packet headers. 32 */ 33 uint16_t 34 ipv4cksum(uint16_t *cp, uint16_t count) 35 { 36 uint_t sum = 0; 37 uint_t oneword = BIT_WRAP; 38 39 if (count == 0) 40 return (0); 41 42 count >>= 1; 43 while (count--) { 44 sum += (uint_t)*cp++; 45 if (sum >= oneword) { /* Wrap carries into low bit */ 46 sum -= oneword; 47 sum++; 48 } 49 } 50 return ((uint16_t)~sum); 51 } 52