1 /* $NetBSD: chksum.c,v 1.8 2022/04/25 14:39:30 rin Exp $ */ 2 3 /*- 4 * Copyright (c) 1996 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Ignatios Souvatzis. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #if HAVE_NBTOOL_CONFIG_H 33 #include "nbtool_config.h" 34 #endif 35 36 #include <stdio.h> 37 #include <unistd.h> 38 #include <sys/types.h> 39 40 #include "chksum.h" 41 42 uint32_t 43 chksum(uint32_t *block, int size) 44 { 45 uint32_t sum, lastsum; 46 int i; 47 48 sum = 0; 49 50 for (i=0; i<size; i++) { 51 lastsum = sum; 52 sum += be32toh(block[i]); 53 if (sum < lastsum) 54 ++sum; 55 } 56 57 return sum; 58 } 59 60 #ifdef TESTSUM 61 uint32_t myblock[8192]; 62 63 int 64 main(int argc, char *argb[]) { 65 int bbsize; 66 uint32_t cks, cks1; 67 68 bbsize = atol(argb[1]); 69 bbsize *= (512 / sizeof (uint32_t)); 70 71 if (4 * bbsize != read(0, myblock, sizeof(uint32_t) * bbsize)) { 72 fprintf(stderr, "short read\n"); 73 exit(1); 74 } 75 fprintf(stderr, "Cksum field = 0x%x, ", myblock[1]); 76 cks = chksum(myblock, bbsize); 77 fprintf(stderr, "cksum = 0x%x\n", cks); 78 myblock[1] += 0xffffffff - cks; 79 fprintf(stderr, "New cksum field = 0x%x, ", myblock[1]); 80 cks1 = chksum(myblock, bbsize); 81 fprintf(stderr, "cksum = 0x%x\n", cks1); 82 } 83 #endif 84