1 /* $NetBSD: primes.c,v 1.22 2018/02/03 15:40:29 christos Exp $ */
2
3 /*
4 * Copyright (c) 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Landon Curt Noll.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/cdefs.h>
36 #ifndef lint
37 __COPYRIGHT("@(#) Copyright (c) 1989, 1993\
38 The Regents of the University of California. All rights reserved.");
39 #endif /* not lint */
40
41 #ifndef lint
42 #if 0
43 static char sccsid[] = "@(#)primes.c 8.5 (Berkeley) 5/10/95";
44 #else
45 __RCSID("$NetBSD: primes.c,v 1.22 2018/02/03 15:40:29 christos Exp $");
46 #endif
47 #endif /* not lint */
48
49 /*
50 * primes - generate a table of primes between two values
51 *
52 * By Landon Curt Noll, http://www.isthe.com/chongo/index.html /\oo/\
53 *
54 * usage:
55 * primes [-dh] [start [stop]]
56 *
57 * Print primes >= start and < stop. If stop is omitted,
58 * the value SPSPMAX is assumed. If start is
59 * omitted, start is read from standard input.
60 * -d: print difference to previous prime, e.g. 3 (1)
61 * -h: print primes in hexadecimal
62 *
63 * validation check: there are 664579 primes between 0 and 10^7
64 */
65
66 #include <ctype.h>
67 #include <err.h>
68 #include <errno.h>
69 #include <inttypes.h>
70 #include <limits.h>
71 #include <math.h>
72 #include <stdio.h>
73 #include <stdlib.h>
74 #include <string.h>
75 #include <unistd.h>
76
77 #include "primes.h"
78
79 /*
80 * Eratosthenes sieve table
81 *
82 * We only sieve the odd numbers. The base of our sieve windows are always
83 * odd. If the base of table is 1, table[i] represents 2*i-1. After the
84 * sieve, table[i] == 1 if and only if 2*i-1 is prime.
85 *
86 * We make TABSIZE large to reduce the overhead of inner loop setup.
87 */
88 static char table[TABSIZE]; /* Eratosthenes sieve of odd numbers */
89
90 static int dflag, hflag;
91
92 static void primes(uint64_t, uint64_t);
93 static uint64_t read_num_buf(void);
94 static void usage(void) __dead;
95
96
97 int
main(int argc,char * argv[])98 main(int argc, char *argv[])
99 {
100 uint64_t start; /* where to start generating */
101 uint64_t stop; /* don't generate at or above this value */
102 int ch;
103 char *p;
104
105 while ((ch = getopt(argc, argv, "dh")) != -1)
106 switch (ch) {
107 case 'd':
108 dflag++;
109 break;
110 case 'h':
111 hflag++;
112 break;
113 case '?':
114 default:
115 usage();
116 }
117 argc -= optind;
118 argv += optind;
119
120 start = 0;
121 stop = (uint64_t)(-1);
122
123 /*
124 * Convert low and high args. Strtoumax(3) sets errno to
125 * ERANGE if the number is too large, but, if there's
126 * a leading minus sign it returns the negation of the
127 * result of the conversion, which we'd rather disallow.
128 */
129 switch (argc) {
130 case 2:
131 /* Start and stop supplied on the command line. */
132 if (argv[0][0] == '-' || argv[1][0] == '-')
133 errx(1, "negative numbers aren't permitted.");
134
135 errno = 0;
136 start = strtoumax(argv[0], &p, 0);
137 if (errno)
138 err(1, "%s", argv[0]);
139 if (*p != '\0')
140 errx(1, "%s: illegal numeric format.", argv[0]);
141
142 errno = 0;
143 stop = strtoumax(argv[1], &p, 0);
144 if (errno)
145 err(1, "%s", argv[1]);
146 if (*p != '\0')
147 errx(1, "%s: illegal numeric format.", argv[1]);
148 break;
149 case 1:
150 /* Start on the command line. */
151 if (argv[0][0] == '-')
152 errx(1, "negative numbers aren't permitted.");
153
154 errno = 0;
155 start = strtoumax(argv[0], &p, 0);
156 if (errno)
157 err(1, "%s", argv[0]);
158 if (*p != '\0')
159 errx(1, "%s: illegal numeric format.", argv[0]);
160 break;
161 case 0:
162 start = read_num_buf();
163 break;
164 default:
165 usage();
166 }
167
168 if (start > stop)
169 errx(1, "start value must be less than stop value.");
170 primes(start, stop);
171 return (0);
172 }
173
174 /*
175 * read_num_buf --
176 * This routine returns a number n, where 0 <= n && n <= ULONG_MAX.
177 */
178 static uint64_t
read_num_buf(void)179 read_num_buf(void)
180 {
181 uint64_t val;
182 char *p, buf[LINE_MAX]; /* > max number of digits. */
183
184 for (;;) {
185 if (fgets(buf, sizeof(buf), stdin) == NULL) {
186 if (ferror(stdin))
187 err(1, "stdin");
188 exit(0);
189 }
190 for (p = buf; isblank((unsigned char)*p); ++p);
191 if (*p == '\n' || *p == '\0')
192 continue;
193 if (*p == '-')
194 errx(1, "negative numbers aren't permitted.");
195 errno = 0;
196 val = strtoumax(buf, &p, 0);
197 if (errno)
198 err(1, "%s", buf);
199 if (*p != '\n')
200 errx(1, "%s: illegal numeric format.", buf);
201 return (val);
202 }
203 }
204
205 /*
206 * primes - sieve and print primes from start up to and but not including stop
207 */
208 static void
primes(uint64_t start,uint64_t stop)209 primes(uint64_t start, uint64_t stop)
210 {
211 char *q; /* sieve spot */
212 uint64_t factor; /* index and factor */
213 char *tab_lim; /* the limit to sieve on the table */
214 const uint64_t *p; /* prime table pointer */
215 uint64_t fact_lim; /* highest prime for current block */
216 uint64_t mod; /* temp storage for mod */
217 uint64_t prev = 0;
218
219 /*
220 * A number of systems can not convert double values into unsigned
221 * longs when the values are larger than the largest signed value.
222 * We don't have this problem, so we can go all the way to ULONG_MAX.
223 */
224 if (start < 3) {
225 start = 2;
226 }
227 if (stop < 3) {
228 stop = 2;
229 }
230 if (stop <= start) {
231 return;
232 }
233
234 /*
235 * be sure that the values are odd, or 2
236 */
237 if (start != 2 && (start&0x1) == 0) {
238 ++start;
239 }
240 if (stop != 2 && (stop&0x1) == 0) {
241 ++stop;
242 }
243
244 /*
245 * quick list of primes <= pr_limit
246 */
247 if (start <= *pr_limit) {
248 /* skip primes up to the start value */
249 for (p = &prime[0], factor = prime[0];
250 factor < stop && p <= pr_limit; factor = *(++p)) {
251 if (factor >= start) {
252 printf(hflag ? "%" PRIx64 : "%" PRIu64, factor);
253 if (dflag) {
254 printf(" (%" PRIu64 ")", factor - prev);
255 }
256 putchar('\n');
257 }
258 prev = factor;
259 }
260 /* return early if we are done */
261 if (p <= pr_limit) {
262 return;
263 }
264 start = *pr_limit+2;
265 }
266
267 /*
268 * we shall sieve a bytemap window, note primes and move the window
269 * upward until we pass the stop point
270 */
271 while (start < stop) {
272 /*
273 * factor out 3, 5, 7, 11 and 13
274 */
275 /* initial pattern copy */
276 factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
277 memcpy(table, &pattern[factor], pattern_size-factor);
278 /* main block pattern copies */
279 for (fact_lim=pattern_size-factor;
280 fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
281 memcpy(&table[fact_lim], pattern, pattern_size);
282 }
283 /* final block pattern copy */
284 memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
285
286 /*
287 * sieve for primes 17 and higher
288 */
289 /* note highest useful factor and sieve spot */
290 if (stop-start > TABSIZE+TABSIZE) {
291 tab_lim = &table[TABSIZE]; /* sieve it all */
292 fact_lim = sqrt(start+1.0+TABSIZE+TABSIZE);
293 } else {
294 tab_lim = &table[(stop-start)/2]; /* partial sieve */
295 fact_lim = sqrt(stop+1.0);
296 }
297 /* sieve for factors >= 17 */
298 factor = 17; /* 17 is first prime to use */
299 p = &prime[7]; /* 19 is next prime, pi(19)=7 */
300 do {
301 /* determine the factor's initial sieve point */
302 mod = start%factor;
303 if (mod & 0x1) {
304 q = &table[(factor-mod)/2];
305 } else {
306 q = &table[mod ? factor-(mod/2) : 0];
307 }
308 /* sieve for our current factor */
309 for ( ; q < tab_lim; q += factor) {
310 *q = '\0'; /* sieve out a spot */
311 }
312 factor = *p++;
313 } while (factor <= fact_lim);
314
315 /*
316 * print generated primes
317 */
318 for (q = table; q < tab_lim; ++q, start+=2) {
319 if (*q) {
320 if (start > SIEVEMAX) {
321 if (!isprime(start))
322 continue;
323 }
324 printf(hflag ? "%" PRIx64 : "%" PRIu64, start);
325 if (dflag && (prev || (start <= *pr_limit))) {
326 printf(" (%" PRIu64 ")", start - prev);
327 }
328 putchar('\n');
329 prev = start;
330 }
331 }
332 }
333 }
334
335 static void
usage(void)336 usage(void)
337 {
338 (void)fprintf(stderr, "usage: primes [-dh] [start [stop]]\n");
339 exit(1);
340 }
341