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/* $OpenBSD: factor.c,v 1.5 1998/08/19 07:40:28 pjanzen Exp $ */
/* $NetBSD: factor.c,v 1.5 1995/03/23 08:28:07 cgd Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Landon Curt Noll.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)factor.c 8.3 (Berkeley) 3/30/94";
#else
static char rcsid[] = "$OpenBSD: factor.c,v 1.5 1998/08/19 07:40:28 pjanzen Exp $";
#endif
#endif /* not lint */
/*
* factor - factor a number into primes
*
* By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
*
* chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
*
* usage:
* factor [number] ...
*
* The form of the output is:
*
* number: factor1 factor1 factor2 factor3 factor3 factor3 ...
*
* where factor1 < factor2 < factor3 < ...
*
* If no args are given, the list of numbers are read from stdin.
*/
#include <sys/types.h>
#include <err.h>
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "primes.h"
/*
* prime[i] is the (i-1)th prime.
*
* We are able to sieve 2^32-1 because this byte table yields all primes
* up to 65537 and 65537^2 > 2^32-1.
*/
extern ubig prime[];
extern ubig *pr_limit; /* largest prime in the prime array */
void pr_fact __P((ubig)); /* print factors of a value */
void usage __P((void));
int
main(argc, argv)
int argc;
char *argv[];
{
ubig val;
int ch;
char *p, buf[100]; /* > max number of digits. */
/* revoke privs */
setegid(getgid());
setgid(getgid());
while ((ch = getopt(argc, argv, "")) != -1)
switch (ch) {
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
/* No args supplied, read numbers from stdin. */
if (argc == 0)
for (;;) {
if (fgets(buf, sizeof(buf), stdin) == NULL) {
if (ferror(stdin))
err(1, "stdin");
exit (0);
}
for (p = buf; isblank(*p); ++p);
if (*p == '\n' || *p == '\0')
continue;
if (*p == '-')
errx(1, "negative numbers aren't permitted.");
errno = 0;
val = strtoul(buf, &p, 10);
if (errno)
err(1, "%s", buf);
if (*p != '\n')
errx(1, "%s: illegal numeric format.", buf);
pr_fact(val);
}
/* Factor the arguments. */
else
for (; *argv != NULL; ++argv) {
if (argv[0][0] == '-')
errx(1, "negative numbers aren't permitted.");
errno = 0;
val = strtoul(argv[0], &p, 10);
if (errno)
err(1, "%s", argv[0]);
if (*p != '\0')
errx(1, "%s: illegal numeric format.", argv[0]);
pr_fact(val);
}
exit(0);
}
/*
* pr_fact - print the factors of a number
*
* If the number is 0 or 1, then print the number and return.
* If the number is < 0, print -1, negate the number and continue
* processing.
*
* Print the factors of the number, from the lowest to the highest.
* A factor will be printed numtiple times if it divides the value
* multiple times.
*
* Factors are printed with leading tabs.
*/
void
pr_fact(val)
ubig val; /* Factor this value. */
{
ubig *fact; /* The factor found. */
/* Firewall - catch 0 and 1. */
if (val == 0) /* Historical practice; 0 just exits. */
exit(0);
if (val == 1) {
(void)printf("1: 1\n");
return;
}
/* Factor value. */
(void)printf("%lu:", val);
for (fact = &prime[0]; val > 1; ++fact) {
/* Look for the smallest factor. */
do {
if (val % (long)*fact == 0)
break;
} while (++fact <= pr_limit);
/* Watch for primes larger than the table. */
if (fact > pr_limit) {
(void)printf(" %lu", val);
break;
}
/* Divide factor out until none are left. */
do {
(void)printf(" %lu", *fact);
val /= (long)*fact;
} while ((val % (long)*fact) == 0);
/* Let the user know we're doing something. */
(void)fflush(stdout);
}
(void)putchar('\n');
}
void
usage()
{
(void)fprintf(stderr, "usage: factor [value ...]\n");
exit (0);
}
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