1 /* $NetBSD: sum1.c,v 1.4 1995/03/26 05:15:23 glass 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93"; 39 #else 40 static char rcsid[] = "$NetBSD: sum1.c,v 1.4 1995/03/26 05:15:23 glass Exp $"; 41 #endif 42 #endif /* not lint */ 43 44 #include <sys/types.h> 45 #include <unistd.h> 46 47 int 48 csum1(fd, cval, clen) 49 register int fd; 50 u_long *cval, *clen; 51 { 52 register u_long total; 53 register int nr; 54 register u_int crc; 55 register u_char *p; 56 u_char buf[8192]; 57 58 /* 59 * 16-bit checksum, rotating right before each addition; 60 * overflow is discarded. 61 */ 62 crc = total = 0; 63 while ((nr = read(fd, buf, sizeof(buf))) > 0) 64 for (total += nr, p = buf; nr--; ++p) { 65 if (crc & 1) 66 crc |= 0x10000; 67 crc = ((crc >> 1) + *p) & 0xffff; 68 } 69 if (nr < 0) 70 return(1); 71 72 *cval = crc; 73 *clen = total; 74 return(0); 75 } 76