/* $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[] = "$NetBSD: factor.c,v 1.5 1995/03/23 08:28:07 cgd 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 <err.h> #include <ctype.h> #include <errno.h> #include <limits.h> #include <stdio.h> #include <stdlib.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); }