1 /* $NetBSD: sum1.c,v 1.9 2003/08/07 11:13:21 agc Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(__RCSID) && !defined(lint) 34 #if 0 35 static char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93"; 36 #else 37 __RCSID("$NetBSD: sum1.c,v 1.9 2003/08/07 11:13:21 agc Exp $"); 38 #endif 39 #endif /* not lint */ 40 41 #include <sys/types.h> 42 #include <unistd.h> 43 44 #include "extern.h" 45 46 int 47 csum1(fd, cval, clen) 48 register int fd; 49 u_int32_t *cval, *clen; 50 { 51 register u_int32_t total; 52 register int nr; 53 register u_int thecrc; 54 register u_char *p; 55 u_char buf[8192]; 56 57 /* 58 * 16-bit checksum, rotating right before each addition; 59 * overflow is discarded. 60 */ 61 thecrc = total = 0; 62 while ((nr = read(fd, buf, sizeof(buf))) > 0) 63 for (total += nr, p = buf; nr--; ++p) { 64 if (thecrc & 1) 65 thecrc |= 0x10000; 66 thecrc = ((thecrc >> 1) + *p) & 0xffff; 67 } 68 if (nr < 0) 69 return(1); 70 71 *cval = thecrc; 72 *clen = total; 73 return(0); 74 } 75