projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 15637ed4 | 1 | /*- |
| 78ed81a3 | 2 | * Copyright (c) 1991, 1993 |
| 3 | * The Regents of the University of California. All rights reserved. | |
| 15637ed4 RG |
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 | |
| 78ed81a3 | 35 | static char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93"; |
| 15637ed4 RG |
36 | #endif /* not lint */ |
| 37 | ||
| 38 | #include <sys/types.h> | |
| 39 | #include <unistd.h> | |
| 40 | ||
| 78ed81a3 | 41 | int |
| 15637ed4 RG |
42 | csum1(fd, cval, clen) |
| 43 | register int fd; | |
| 44 | u_long *cval, *clen; | |
| 45 | { | |
| 46 | register u_long 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 | } |