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/* factor -- print factors of n. lose if n > 2^32.
Copyright (C) 86, 1995 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Written by Paul Rubin <phr@ocf.berkeley.edu>.
Adapted for GNU, fixed to factor UINT_MAX by Jim Meyering. */
#include <config.h>
#include <stdio.h>
#include <math.h>
#include <sys/types.h>
#include <assert.h>
#define NDEBUG 1
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif /* HAVE_LIMITS_H */
#ifndef UINT_MAX
# define UINT_MAX ((unsigned int) ~(unsigned int) 0)
#endif
#ifndef INT_MAX
# define INT_MAX ((int) (UINT_MAX >> 1))
#endif
#include "system.h"
#include "long-options.h"
#include "error.h"
#include "xstrtoul.h"
#include "readtokens.h"
/* Token delimiters when reading from a file. */
#define DELIM "\n\t "
/* FIXME: if this program is ever modified to factor integers larger
than 2^128, this constant (and the algorithm :-) will have to change. */
#define MAX_N_FACTORS 128
/* The name this program was run with. */
char *program_name;
static void
usage (int status)
{
if (status != 0)
fprintf (stderr, _("Try `%s --help' for more information.\n"),
program_name);
else
{
printf (_("\
Usage: %s [NUMBER...]\n\
or: %s OPTION\n\
"),
program_name, program_name);
printf (_("\
\n\
--help display this help and exit\n\
--version output version information and exit\n\
"));
}
exit (status);
}
/* FIXME: comment */
static int
factor (long unsigned int n0, int max_n_factors, long unsigned int *factors)
{
register unsigned long n = n0, d;
int n_factors = 0;
unsigned int sqrt_n;
if (n < 1)
return n_factors;
while (n % 2 == 0)
{
assert (n_factors < max_n_factors);
factors[n_factors++] = 2;
n /= 2;
}
/* The exit condition in the following loop is correct because
any time it is tested one of these 3 conditions holds:
(1) d divides n
(2) n is prime
(3) n is composite but has no factors less than d.
If (1) or (2) obviously the right thing happens.
If (3), then since n is composite it is >= d^2. */
sqrt_n = (unsigned int) sqrt ((double) n);
for (d = 3; d <= sqrt_n; d += 2)
{
while (n % d == 0)
{
assert (n_factors < max_n_factors);
factors[n_factors++] = d;
n /= d;
}
}
if (n != 1 || n0 == 1)
{
assert (n_factors < max_n_factors);
factors[n_factors++] = n;
}
return n_factors;
}
/* FIXME: comment */
static int
print_factors (const char *s)
{
unsigned long int factors[MAX_N_FACTORS];
unsigned long n;
int n_factors;
int i;
if (xstrtoul (s, NULL, 10, &n, NULL) != LONGINT_OK)
{
error (0, 0, _("%s: invalid argument"), s);
return 1;
}
n_factors = factor (n, MAX_N_FACTORS, factors);
printf ("%lu:", n);
for (i = 0; i < n_factors; i++)
printf (" %lu", factors[i]);
putchar ('\n');
return 0;
}
static int
do_stdin (void)
{
int fail = 0;
token_buffer tokenbuffer;
init_tokenbuffer (&tokenbuffer);
for (;;)
{
long int token_length;
token_length = readtoken (stdin, DELIM, sizeof (DELIM) - 1,
&tokenbuffer);
if (token_length < 0)
break;
fail |= print_factors (tokenbuffer.buffer);
}
free (tokenbuffer.buffer);
return fail;
}
int
main (int argc, char **argv)
{
int fail;
program_name = argv[0];
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
parse_long_options (argc, argv, "factor", PACKAGE_VERSION, usage);
fail = 0;
if (argc == 1)
fail = do_stdin ();
else
{
int i;
for (i = 1; i < argc; i++)
fail |= print_factors (argv[i]);
}
exit (fail);
}
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