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