OpenBSD-4.6/games/factor/factor.c
/* $OpenBSD: factor.c,v 1.18 2008/03/17 09:17:56 sobrado 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. 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 8.4 (Berkeley) 5/4/95";
#else
static char rcsid[] = "$OpenBSD: factor.c,v 1.18 2008/03/17 09:17:56 sobrado 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 <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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 const ubig prime[];
extern const ubig *pr_limit; /* largest prime in the prime array */
extern const char pattern[];
extern const int pattern_size;
void pr_fact(u_int64_t); /* print factors of a value */
void pr_bigfact(u_int64_t);
void usage(void);
int
main(int argc, char *argv[])
{
u_int64_t val;
int ch;
char *p, buf[100]; /* > max number of digits. */
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);
}
buf[strcspn(buf, "\n")] = '\0';
for (p = buf; isblank(*p); ++p);
if (*p == '\0')
continue;
if (*p == '-')
errx(1, "negative numbers aren't permitted.");
errno = 0;
val = strtouq(buf, &p, 10);
if (errno)
err(1, "%s", buf);
for (; isblank(*p); ++p);
if (*p != '\0')
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 = strtouq(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 multiple times if it divides the value
* multiple times.
*
* Factors are printed with leading tabs.
*/
void
pr_fact(u_int64_t val) /* Factor this value. */
{
const 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("%llu:", val);
fflush(stdout);
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) {
if (val > BIG)
pr_bigfact(val);
else
(void)printf(" %llu", val);
break;
}
/* Divide factor out until none are left. */
do {
(void)printf(" %lu", (unsigned long) *fact);
val /= (long)*fact;
} while ((val % (long)*fact) == 0);
/* Let the user know we're doing something. */
(void)fflush(stdout);
}
(void)putchar('\n');
}
/* At this point, our number may have factors greater than those in primes[];
* however, we can generate primes up to 32 bits (see primes(6)), which is
* sufficient to factor a 64-bit quad.
*/
void
pr_bigfact(u_int64_t val) /* Factor this value. */
{
ubig start, stop, factor;
char *q;
const ubig *p;
ubig fact_lim, mod;
char *tab_lim;
char table[TABSIZE]; /* Eratosthenes sieve of odd numbers */
start = *pr_limit + 2;
stop = (ubig)sqrt((double)val);
if ((stop & 0x1) == 0)
stop++;
/*
* Following code barely modified from that in primes(6)
*
* we shall sieve a bytemap window, note primes and move the window
* upward until we pass the stop point
*/
while (start < stop) {
/*
* factor out 3, 5, 7, 11 and 13
*/
/* initial pattern copy */
factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
memcpy(table, &pattern[factor], pattern_size-factor);
/* main block pattern copies */
for (fact_lim = pattern_size - factor;
fact_lim + pattern_size <= TABSIZE; fact_lim += pattern_size) {
memcpy(&table[fact_lim], pattern, pattern_size);
}
/* final block pattern copy */
memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
if (stop-start > TABSIZE+TABSIZE) {
tab_lim = &table[TABSIZE]; /* sieve it all */
fact_lim = (int)sqrt(
(double)(start)+TABSIZE+TABSIZE+1.0);
} else {
tab_lim = &table[(stop - start)/2]; /* partial sieve */
fact_lim = (int)sqrt((double)(stop) + 1.0);
}
/* sieve for factors >= 17 */
factor = 17; /* 17 is first prime to use */
p = &prime[7]; /* 19 is next prime, pi(19)=7 */
do {
/* determine the factor's initial sieve point */
mod = start % factor;
if (mod & 0x1)
q = &table[(factor-mod)/2];
else
q = &table[mod ? factor-(mod/2) : 0];
/* sieve for our current factor */
for ( ; q < tab_lim; q += factor) {
*q = '\0'; /* sieve out a spot */
}
} while ((factor=(ubig)(*(p++))) <= fact_lim);
/*
* use generated primes
*/
for (q = table; q < tab_lim; ++q, start+=2) {
if (*q) {
if (val % start == 0) {
do {
(void)printf(" %lu", (unsigned long) start);
val /= start;
} while ((val % start) == 0);
(void)fflush(stdout);
stop = (ubig)sqrt((double)val);
if ((stop & 0x1) == 0)
stop++;
}
}
}
}
if (val > 1)
printf(" %llu", val);
}
void
usage(void)
{
(void)fprintf(stderr, "usage: factor [number ...]\n");
exit (1);
}