1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
/* 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., 675 Mass Ave, Cambridge, MA 02139, 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 "version.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;
}
void
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", version_string, 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);
}
|
