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/* factor -- print prime factors of n.
Copyright (C) 86, 1995-2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by Paul Rubin <phr@ocf.berkeley.edu>.
Adapted for GNU, fixed to factor UINT_MAX by Jim Meyering. */
#include <config.h>
#include <getopt.h>
#include <stdio.h>
#include <sys/types.h>
#include <assert.h>
#define NDEBUG 1
#include "system.h"
#include "error.h"
#include "inttostr.h"
#include "long-options.h"
#include "readtokens.h"
#include "xstrtol.h"
/* The official name of this program (e.g., no `g' prefix). */
#define PROGRAM_NAME "factor"
#define AUTHORS "Paul Rubin"
/* 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 trial divisor increment wheel. Use it to skip over divisors that
are composites of 2, 3, 5, 7, or 11. The part from WHEEL_START up to
WHEEL_END is reused periodically, while the "lead in" is used to test
for those primes and to jump onto the wheel. For more information, see
http://www.utm.edu/research/primes/glossary/WheelFactorization.html */
#include "wheel-size.h" /* For the definition of WHEEL_SIZE. */
static const unsigned char wheel_tab[] =
{
#include "wheel.h"
};
#define WHEEL_START (wheel_tab + WHEEL_SIZE)
#define WHEEL_END (wheel_tab + (sizeof wheel_tab / sizeof wheel_tab[0]))
/* The name this program was run with. */
char *program_name;
void
usage (int status)
{
if (status != EXIT_SUCCESS)
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);
fputs (_("\
Print the prime factors of each NUMBER.\n\
\n\
"), stdout);
fputs (HELP_OPTION_DESCRIPTION, stdout);
fputs (VERSION_OPTION_DESCRIPTION, stdout);
fputs (_("\
\n\
Print the prime factors of all specified integer NUMBERs. If no arguments\n\
are specified on the command line, they are read from standard input.\n\
"), stdout);
printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
}
exit (status);
}
/* FIXME: comment */
static size_t
factor (uintmax_t n0, size_t max_n_factors, uintmax_t *factors)
{
uintmax_t n = n0, d, q;
size_t n_factors = 0;
unsigned char const *w = wheel_tab;
if (n <= 1)
return n_factors;
/* 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. */
d = 2;
do
{
q = n / d;
while (n == q * d)
{
assert (n_factors < max_n_factors);
factors[n_factors++] = d;
n = q;
q = n / d;
}
d += *(w++);
if (w == WHEEL_END)
w = WHEEL_START;
}
while (d <= q);
if (n != 1 || n0 == 1)
{
assert (n_factors < max_n_factors);
factors[n_factors++] = n;
}
return n_factors;
}
/* FIXME: comment */
static bool
print_factors (const char *s)
{
uintmax_t factors[MAX_N_FACTORS];
uintmax_t n;
size_t n_factors;
size_t i;
char buf[INT_BUFSIZE_BOUND (uintmax_t)];
strtol_error err;
if ((err = xstrtoumax (s, NULL, 10, &n, "")) != LONGINT_OK)
{
if (err == LONGINT_OVERFLOW)
error (0, 0, _("`%s' is too large"), s);
else
error (0, 0, _("`%s' is not a valid positive integer"), s);
return false;
}
n_factors = factor (n, MAX_N_FACTORS, factors);
printf ("%s:", umaxtostr (n, buf));
for (i = 0; i < n_factors; i++)
printf (" %s", umaxtostr (factors[i], buf));
putchar ('\n');
return true;
}
static bool
do_stdin (void)
{
bool ok = true;
token_buffer tokenbuffer;
init_tokenbuffer (&tokenbuffer);
for (;;)
{
size_t token_length = readtoken (stdin, DELIM, sizeof (DELIM) - 1,
&tokenbuffer);
if (token_length == (size_t) -1)
break;
ok &= print_factors (tokenbuffer.buffer);
}
free (tokenbuffer.buffer);
return ok;
}
int
main (int argc, char **argv)
{
bool ok;
initialize_main (&argc, &argv);
program_name = argv[0];
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
atexit (close_stdout);
parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
usage, AUTHORS, (char const *) NULL);
if (getopt_long (argc, argv, "", NULL, NULL) != -1)
usage (EXIT_FAILURE);
if (argc <= optind)
ok = do_stdin ();
else
{
int i;
for (i = optind; i < argc; i++)
if (! print_factors (argv[i]))
usage (EXIT_FAILURE);
ok = true;
}
exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}
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