sum1.c revision 1590
11590Srgrimes/*- 21590Srgrimes * Copyright (c) 1991, 1993 31590Srgrimes * The Regents of the University of California. All rights reserved. 41590Srgrimes * 51590Srgrimes * Redistribution and use in source and binary forms, with or without 61590Srgrimes * modification, are permitted provided that the following conditions 71590Srgrimes * are met: 81590Srgrimes * 1. Redistributions of source code must retain the above copyright 91590Srgrimes * notice, this list of conditions and the following disclaimer. 101590Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 111590Srgrimes * notice, this list of conditions and the following disclaimer in the 121590Srgrimes * documentation and/or other materials provided with the distribution. 131590Srgrimes * 3. All advertising materials mentioning features or use of this software 141590Srgrimes * must display the following acknowledgement: 151590Srgrimes * This product includes software developed by the University of 161590Srgrimes * California, Berkeley and its contributors. 171590Srgrimes * 4. Neither the name of the University nor the names of its contributors 181590Srgrimes * may be used to endorse or promote products derived from this software 191590Srgrimes * without specific prior written permission. 201590Srgrimes * 211590Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 221590Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 231590Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 241590Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 251590Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 261590Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 271590Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 281590Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 291590Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 301590Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 311590Srgrimes * SUCH DAMAGE. 321590Srgrimes */ 331590Srgrimes 341590Srgrimes#ifndef lint 351590Srgrimesstatic char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93"; 361590Srgrimes#endif /* not lint */ 371590Srgrimes 381590Srgrimes#include <sys/types.h> 391590Srgrimes#include <unistd.h> 401590Srgrimes 411590Srgrimesint 421590Srgrimescsum1(fd, cval, clen) 431590Srgrimes register int fd; 441590Srgrimes u_long *cval, *clen; 451590Srgrimes{ 461590Srgrimes register u_long total; 471590Srgrimes register int nr; 481590Srgrimes register u_int crc; 491590Srgrimes register u_char *p; 501590Srgrimes u_char buf[8192]; 511590Srgrimes 521590Srgrimes /* 531590Srgrimes * 16-bit checksum, rotating right before each addition; 541590Srgrimes * overflow is discarded. 551590Srgrimes */ 561590Srgrimes crc = total = 0; 571590Srgrimes while ((nr = read(fd, buf, sizeof(buf))) > 0) 581590Srgrimes for (total += nr, p = buf; nr--; ++p) { 591590Srgrimes if (crc & 1) 601590Srgrimes crc |= 0x10000; 611590Srgrimes crc = ((crc >> 1) + *p) & 0xffff; 621590Srgrimes } 631590Srgrimes if (nr < 0) 641590Srgrimes return(1); 651590Srgrimes 661590Srgrimes *cval = crc; 671590Srgrimes *clen = total; 681590Srgrimes return(0); 691590Srgrimes} 70