minix/games/factor/factor.c
Thomas Cort c1f592a24c Importing games/factor
Replaces commands/factor. No Minix specific changes needed.

Change-Id: Ie2a58534c59a1ebbf922d483fb27abd8dffd1f5f
2014-07-28 17:05:16 +02:00

378 lines
8.6 KiB
C

/* $NetBSD: factor.c,v 1.26 2011/11/09 20:17:44 drochner 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1989, 1993\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)factor.c 8.4 (Berkeley) 5/4/95";
#else
__RCSID("$NetBSD: factor.c,v 1.26 2011/11/09 20:17:44 drochner 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 <ctype.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef HAVE_OPENSSL
#include <openssl/bn.h>
#else
typedef long BIGNUM;
typedef u_long BN_ULONG;
static int BN_dec2bn(BIGNUM **a, const char *str);
#define BN_new() ((BIGNUM *)calloc(sizeof(BIGNUM), 1))
#define BN_is_zero(v) (*(v) == 0)
#define BN_is_one(v) (*(v) == 1)
#define BN_mod_word(a, b) (*(a) % (b))
#endif
#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 */
#if 0 /* debugging: limit table use to stress the "pollard" code */
#define pr_limit &prime[0]
#endif
#define PRIME_CHECKS 5
#ifdef HAVE_OPENSSL
static BN_CTX *ctx; /* just use a global context */
#endif
static void pr_fact(BIGNUM *); /* print factors of a value */
static void BN_print_dec_fp(FILE *, const BIGNUM *);
static void usage(void) __dead;
#ifdef HAVE_OPENSSL
static void pollard_rho(BIGNUM *); /* print factors for big numbers */
#else
static char *BN_bn2dec(const BIGNUM *);
static BN_ULONG BN_div_word(BIGNUM *, BN_ULONG);
#endif
#ifndef HAVE_OPENSSL
static int
BN_dec2bn(BIGNUM **a, const char *str)
{
char *p;
errno = 0;
**a = strtoul(str, &p, 10);
if (errno)
err(1, "%s", str);
return (*p == '\n' || *p == '\0');
}
#endif
int
main(int argc, char *argv[])
{
BIGNUM *val;
int ch;
char *p, buf[LINE_MAX]; /* > max number of digits. */
#ifdef HAVE_OPENSSL
ctx = BN_CTX_new();
#endif
val = BN_new();
if (val == NULL)
errx(1, "can't initialise bignum");
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((unsigned char)*p); ++p);
if (*p == '\n' || *p == '\0')
continue;
if (*p == '-')
errx(1, "negative numbers aren't permitted.");
if (BN_dec2bn(&val, buf) == 0)
errx(1, "%s: illegal numeric format.", argv[0]);
pr_fact(val);
}
/* Factor the arguments. */
else
for (; *argv != NULL; ++argv) {
if (argv[0][0] == '-')
errx(1, "numbers <= 1 aren't permitted.");
if (BN_dec2bn(&val, argv[0]) == 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.
*/
static void
pr_fact(BIGNUM *val)
{
const ubig *fact; /* The factor found. */
/* Firewall - catch 0 and 1. */
if (BN_is_zero(val) || BN_is_one(val))
errx(1, "numbers <= 1 aren't permitted.");
/* Factor value. */
BN_print_dec_fp(stdout, val);
putchar(':');
for (fact = &prime[0]; !BN_is_one(val); ++fact) {
/* Look for the smallest factor. */
while (fact <= pr_limit) {
if (BN_mod_word(val, (BN_ULONG)*fact) == 0)
break;
fact++;
}
/* Watch for primes larger than the table. */
if (fact > pr_limit) {
#ifdef HAVE_OPENSSL
BIGNUM *bnfact;
bnfact = BN_new();
BN_set_word(bnfact, (BN_ULONG)*(fact - 1));
BN_sqr(bnfact, bnfact, ctx);
if (BN_cmp(bnfact, val) > 0
|| BN_is_prime(val, PRIME_CHECKS, NULL, NULL,
NULL) == 1) {
putchar(' ');
BN_print_dec_fp(stdout, val);
} else
pollard_rho(val);
#else
printf(" %s", BN_bn2dec(val));
#endif
break;
}
/* Divide factor out until none are left. */
do {
printf(" %lu", *fact);
BN_div_word(val, (BN_ULONG)*fact);
} while (BN_mod_word(val, (BN_ULONG)*fact) == 0);
/* Let the user know we're doing something. */
fflush(stdout);
}
putchar('\n');
}
/*
* Sigh.. No _decimal_ output to file functions in BN.
*/
static void
BN_print_dec_fp(FILE *fp, const BIGNUM *num)
{
char *buf;
buf = BN_bn2dec(num);
if (buf == NULL)
return; /* XXX do anything here? */
fprintf(fp, "%s", buf);
free(buf);
}
void
usage(void)
{
fprintf(stderr, "usage: factor [value ...]\n");
exit (0);
}
#ifdef HAVE_OPENSSL
static void
pollard_rho(BIGNUM *val)
{
BIGNUM *x, *y, *tmp, *num;
BN_ULONG a;
unsigned int steps_taken, steps_limit;
x = BN_new();
y = BN_new();
tmp = BN_new();
num = BN_new();
a = 1;
restart:
steps_taken = 0;
steps_limit = 2;
BN_set_word(x, 1);
BN_copy(y, x);
for (;;) {
BN_sqr(tmp, x, ctx);
BN_add_word(tmp, a);
BN_mod(x, tmp, val, ctx);
BN_sub(tmp, x, y);
if (BN_is_zero(tmp)) {
#ifdef DEBUG
printf(" (loop)");
#endif
a++;
goto restart;
}
BN_gcd(tmp, tmp, val, ctx);
if (!BN_is_one(tmp)) {
if (BN_is_prime(tmp, PRIME_CHECKS, NULL, NULL,
NULL) == 1) {
putchar(' ');
BN_print_dec_fp(stdout, tmp);
} else {
#ifdef DEBUG
printf(" (recurse for ");
BN_print_dec_fp(stdout, tmp);
putchar(')');
#endif
pollard_rho(BN_dup(tmp));
#ifdef DEBUG
printf(" (back)");
#endif
}
fflush(stdout);
BN_div(num, NULL, val, tmp, ctx);
if (BN_is_one(num))
return;
if (BN_is_prime(num, PRIME_CHECKS, NULL, NULL,
NULL) == 1) {
putchar(' ');
BN_print_dec_fp(stdout, num);
fflush(stdout);
return;
}
BN_copy(val, num);
goto restart;
}
steps_taken++;
if (steps_taken == steps_limit) {
BN_copy(y, x); /* teleport the turtle */
steps_taken = 0;
steps_limit *= 2;
if (steps_limit == 0) {
#ifdef DEBUG
printf(" (overflow)");
#endif
a++;
goto restart;
}
}
}
}
#else
char *
BN_bn2dec(const BIGNUM *val)
{
char *buf;
buf = malloc(100);
if (!buf)
return buf;
snprintf(buf, 100, "%ld", (long)*val);
return buf;
}
static BN_ULONG
BN_div_word(BIGNUM *a, BN_ULONG b)
{
BN_ULONG mod;
mod = *a % b;
*a /= b;
return mod;
}
#endif