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
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
|
/* factor -- print prime factors of n.
Copyright (C) 86, 1995-2001 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 <sys/types.h>
#include <assert.h>
#define NDEBUG 1
#include "system.h"
#include "closeout.h"
#include "error.h"
#include "human.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 */
static const unsigned int wheel_tab[] = {
/* lead in: */ 1, 2, 2, 4, 2, /* and the periodic tail: */
4, 2, 4, 6, 2, 6, 4, 2, 4, 6, 6, 2, 6, 4, 2, 6, 4, 6, 8, 4,
2, 4, 2, 4,14, 4, 6, 2,10, 2, 6, 6, 4, 2, 4, 6, 2,10, 2, 4,
2,12,10, 2, 4, 2, 4, 6, 2, 6, 4, 6, 6, 6, 2, 6, 4, 2, 6, 4,
6, 8, 4, 2, 4, 6, 8, 6,10, 2, 4, 6, 2, 6, 6, 4, 2, 4, 6, 2,
6, 4, 2, 6,10, 2,10, 2, 4, 2, 4, 6, 8, 4, 2, 4,12, 2, 6, 4,
2, 6, 4, 6,12, 2, 4, 2, 4, 8, 6, 4, 6, 2, 4, 6, 2, 6,10, 2,
4, 6, 2, 6, 4, 2, 4, 2,10, 2,10, 2, 4, 6, 6, 2, 6, 6, 4, 6,
6, 2, 6, 4, 2, 6, 4, 6, 8, 4, 2, 6, 4, 8, 6, 4, 6, 2, 4, 6,
8, 6, 4, 2,10, 2, 6, 4, 2, 4, 2,10, 2,10, 2, 4, 2, 4, 8, 6,
4, 2, 4, 6, 6, 2, 6, 4, 8, 4, 6, 8, 4, 2, 4, 2, 4, 8, 6, 4,
6, 6, 6, 2, 6, 6, 4, 2, 4, 6, 2, 6, 4, 2, 4, 2,10, 2,10, 2,
6, 4, 6, 2, 6, 4, 2, 4, 6, 6, 8, 4, 2, 6,10, 8, 4, 2, 4, 2,
4, 8,10, 6, 2, 4, 8, 6, 6, 4, 2, 4, 6, 2, 6, 4, 6, 2,10, 2,
10, 2, 4, 2, 4, 6, 2, 6, 4, 2, 4, 6, 6, 2, 6, 6, 6, 4, 6, 8,
4, 2, 4, 2, 4, 8, 6, 4, 8, 4, 6, 2, 6, 6, 4, 2, 4, 6, 8, 4,
2, 4, 2,10, 2,10, 2, 4, 2, 4, 6, 2,10, 2, 4, 6, 8, 6, 4, 2,
6, 4, 6, 8, 4, 6, 2, 4, 8, 6, 4, 6, 2, 4, 6, 2, 6, 6, 4, 6,
6, 2, 6, 6, 4, 2,10, 2,10, 2, 4, 2, 4, 6, 2, 6, 4, 2,10, 6,
2, 6, 4, 2, 6, 4, 6, 8, 4, 2, 4, 2,12, 6, 4, 6, 2, 4, 6, 2,
12, 4, 2, 4, 8, 6, 4, 2, 4, 2,10, 2,10, 6, 2, 4, 6, 2, 6, 4,
2, 4, 6, 6, 2, 6, 4, 2,10, 6, 8, 6, 4, 2, 4, 8, 6, 4, 6, 2,
4, 6, 2, 6, 6, 6, 4, 6, 2, 6, 4, 2, 4, 2,10,12, 2, 4, 2,10,
2, 6, 4, 2, 4, 6, 6, 2,10, 2, 6, 4,14, 4, 2, 4, 2, 4, 8, 6,
4, 6, 2, 4, 6, 2, 6, 6, 4, 2, 4, 6, 2, 6, 4, 2, 4,12, 2,12};
#define WHEEL_START (wheel_tab + 5)
#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 != 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 (_("\
Print the prime factors of each NUMBER.\n\
\n\
--help display this help and exit\n\
--version output version information and exit\n\
\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\
"));
puts (_("\nReport bugs to <bug-sh-utils@gnu.org>."));
}
exit (status);
}
/* FIXME: comment */
static int
factor (uintmax_t n0, int max_n_factors, uintmax_t *factors)
{
register uintmax_t n = n0, d, q;
int n_factors = 0;
unsigned int 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 int
print_factors (const char *s)
{
uintmax_t factors[MAX_N_FACTORS];
uintmax_t n;
int n_factors;
int i;
char buf[LONGEST_HUMAN_READABLE + 1];
if (xstrtoumax (s, NULL, 10, &n, "") != LONGINT_OK)
{
error (0, 0, _("`%s' is not a valid positive integer"), s);
return 1;
}
n_factors = factor (n, MAX_N_FACTORS, factors);
printf ("%s:", human_readable (n, buf, 1, 1));
for (i = 0; i < n_factors; i++)
printf (" %s", human_readable (factors[i], buf, 1, 1));
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);
atexit (close_stdout);
parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
AUTHORS, usage);
/* The above handles --help and --version.
Since there is no other invocation of getopt, handle `--' here. */
if (argc > 1 && STREQ (argv[1], "--"))
{
--argc;
++argv;
}
fail = 0;
if (argc == 1)
fail = do_stdin ();
else
{
int i;
for (i = 1; i < argc; i++)
fail |= print_factors (argv[i]);
}
if (fail)
usage (1);
exit (fail);
}
|
