| Uwe Hermann | c52761b | 2008-03-20 00:02:07 +0000 | [diff] [blame] | 1 | /* |
| Uwe Hermann | 6a441bf | 2008-03-20 19:54:59 +0000 | [diff] [blame] | 2 | * This file is part of the libpayload project. |
| 3 | * |
| Uwe Hermann | 661e380 | 2008-03-21 18:37:23 +0000 | [diff] [blame^] | 4 | * It has originally been taken from the FreeBSD project. |
| Uwe Hermann | c52761b | 2008-03-20 00:02:07 +0000 | [diff] [blame] | 5 | * |
| 6 | * Copyright (c) 2001 Charles Mott <cm@linktel.net> |
| 7 | * All rights reserved. |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * 1. Redistributions of source code must retain the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer. |
| 14 | * 2. Redistributions in binary form must reproduce the above copyright |
| 15 | * notice, this list of conditions and the following disclaimer in the |
| 16 | * documentation and/or other materials provided with the distribution. |
| 17 | * |
| 18 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| 19 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 20 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 21 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 22 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 23 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 24 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 25 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 26 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 27 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 28 | * SUCH DAMAGE. |
| 29 | */ |
| 30 | |
| 31 | #include <libpayload.h> |
| 32 | |
| 33 | unsigned short ipchksum(const unsigned short *ptr, unsigned long nbytes) |
| 34 | { |
| Uwe Hermann | 6a441bf | 2008-03-20 19:54:59 +0000 | [diff] [blame] | 35 | int sum, oddbyte; |
| Uwe Hermann | c52761b | 2008-03-20 00:02:07 +0000 | [diff] [blame] | 36 | |
| Uwe Hermann | 6a441bf | 2008-03-20 19:54:59 +0000 | [diff] [blame] | 37 | sum = 0; |
| 38 | while (nbytes > 1) { |
| 39 | sum += *ptr++; |
| 40 | nbytes -= 2; |
| 41 | } |
| 42 | if (nbytes == 1) { |
| 43 | oddbyte = 0; |
| 44 | ((u8 *) & oddbyte)[0] = *(u8 *) ptr; |
| 45 | ((u8 *) & oddbyte)[1] = 0; |
| 46 | sum += oddbyte; |
| 47 | } |
| 48 | sum = (sum >> 16) + (sum & 0xffff); |
| 49 | sum += (sum >> 16); |
| 50 | return (~sum); |
| Uwe Hermann | c52761b | 2008-03-20 00:02:07 +0000 | [diff] [blame] | 51 | } |