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Annotation of src/usr.bin/cksum/sum2.c, Revision 1.2

1.2     ! niklas      1: /*     $OpenBSD$       */
        !             2: /*     $NetBSD: sum2.c,v 1.5 1996/02/27 21:17:28 cgd Exp $     */
1.1       deraadt     3:
                      4: /*-
                      5:  * Copyright (c) 1991, 1993
                      6:  *     The Regents of the University of California.  All rights reserved.
                      7:  *
                      8:  * Redistribution and use in source and binary forms, with or without
                      9:  * modification, are permitted provided that the following conditions
                     10:  * are met:
                     11:  * 1. Redistributions of source code must retain the above copyright
                     12:  *    notice, this list of conditions and the following disclaimer.
                     13:  * 2. Redistributions in binary form must reproduce the above copyright
                     14:  *    notice, this list of conditions and the following disclaimer in the
                     15:  *    documentation and/or other materials provided with the distribution.
                     16:  * 3. All advertising materials mentioning features or use of this software
                     17:  *    must display the following acknowledgement:
                     18:  *     This product includes software developed by the University of
                     19:  *     California, Berkeley and its contributors.
                     20:  * 4. Neither the name of the University nor the names of its contributors
                     21:  *    may be used to endorse or promote products derived from this software
                     22:  *    without specific prior written permission.
                     23:  *
                     24:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     25:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     26:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     27:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     28:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     29:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     30:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     31:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     32:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     33:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     34:  * SUCH DAMAGE.
                     35:  */
                     36:
                     37: #ifndef lint
                     38: #if 0
                     39: static char sccsid[] = "@(#)sum2.c     8.1 (Berkeley) 6/6/93";
1.2     ! niklas     40: static char rcsid[] = "$NetBSD: sum2.c,v 1.5 1996/02/27 21:17:28 cgd Exp $";
1.1       deraadt    41: #else
1.2     ! niklas     42: static char rcsid[] = "$OpenBSD$";
1.1       deraadt    43: #endif
                     44: #endif /* not lint */
                     45:
                     46: #include <sys/types.h>
                     47: #include <unistd.h>
                     48:
1.2     ! niklas     49: #include "extern.h"
        !            50:
1.1       deraadt    51: int
                     52: csum2(fd, cval, clen)
                     53:        register int fd;
1.2     ! niklas     54:        u_int32_t *cval, *clen;
1.1       deraadt    55: {
1.2     ! niklas     56:        register u_int32_t crc, total;
1.1       deraadt    57:        register int nr;
                     58:        register u_char *p;
                     59:        u_char buf[8192];
                     60:
                     61:        /*
                     62:         * Draft 8 POSIX 1003.2:
                     63:         *
                     64:         *   s = sum of all bytes
                     65:         *   r = s % 2^16 + (s % 2^32) / 2^16
                     66:         * crc = (r % 2^16) + r / 2^16
                     67:         */
                     68:        crc = total = 0;
                     69:        while ((nr = read(fd, buf, sizeof(buf))) > 0)
                     70:                for (total += nr, p = buf; nr--; ++p)
                     71:                        crc += *p;
                     72:        if (nr < 0)
                     73:                return(1);
                     74:
                     75:        crc = (crc & 0xffff) + (crc >> 16);
                     76:        crc = (crc & 0xffff) + (crc >> 16);
                     77:
                     78:        *cval = crc;
                     79:        *clen = total;
                     80:        return(0);
                     81: }