xref: /freebsd/usr.bin/primes/primes.c (revision fd9a4a67d053a51349ba6eba5ea61a7cd2cf20af)
1 /*
2  * Copyright (c) 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Landon Curt Noll.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 static const char copyright[] =
35 "@(#) Copyright (c) 1989, 1993\n\
36 	The Regents of the University of California.  All rights reserved.\n";
37 #endif /* not lint */
38 
39 #ifndef lint
40 #if 0
41 static char sccsid[] = "@(#)primes.c	8.5 (Berkeley) 5/10/95";
42 #endif
43 #endif /* not lint */
44 
45 /*
46  * primes - generate a table of primes between two values
47  *
48  * By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
49  *
50  * chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
51  *
52  * usage:
53  *	primes [-h] [start [stop]]
54  *
55  *	Print primes >= start and < stop.  If stop is omitted,
56  *	the value 18446744073709551615 (2^64-1) is assumed.  If
57  *	start is omitted, start is read from standard input.
58  *
59  * validation check: there are 664579 primes between 0 and 10^7
60  */
61 
62 #include <capsicum_helpers.h>
63 #include <ctype.h>
64 #include <err.h>
65 #include <errno.h>
66 #include <inttypes.h>
67 #include <limits.h>
68 #include <math.h>
69 #include <stdio.h>
70 #include <stdlib.h>
71 #include <string.h>
72 #include <nl_types.h>
73 #include <unistd.h>
74 
75 #include "primes.h"
76 
77 /*
78  * Eratosthenes sieve table
79  *
80  * We only sieve the odd numbers.  The base of our sieve windows are always
81  * odd.  If the base of table is 1, table[i] represents 2*i-1.  After the
82  * sieve, table[i] == 1 if and only if 2*i-1 is prime.
83  *
84  * We make TABSIZE large to reduce the overhead of inner loop setup.
85  */
86 static char table[TABSIZE];	 /* Eratosthenes sieve of odd numbers */
87 
88 static int	hflag;
89 
90 static void	primes(ubig, ubig);
91 static ubig	read_num_buf(void);
92 static void	usage(void);
93 
94 int
95 main(int argc, char *argv[])
96 {
97 	ubig start;		/* where to start generating */
98 	ubig stop;		/* don't generate at or above this value */
99 	int ch;
100 	char *p;
101 
102 	caph_cache_catpages();
103 	if (caph_enter() < 0)
104 		err(1, "cap_enter");
105 
106 	while ((ch = getopt(argc, argv, "h")) != -1)
107 		switch (ch) {
108 		case 'h':
109 			hflag++;
110 			break;
111 		case '?':
112 		default:
113 			usage();
114 		}
115 	argc -= optind;
116 	argv += optind;
117 
118 	start = 0;
119 	stop = (uint64_t)(-1);
120 
121 	/*
122 	 * Convert low and high args.  Strtoumax(3) sets errno to
123 	 * ERANGE if the number is too large, but, if there's
124 	 * a leading minus sign it returns the negation of the
125 	 * result of the conversion, which we'd rather disallow.
126 	 */
127 	switch (argc) {
128 	case 2:
129 		/* Start and stop supplied on the command line. */
130 		if (argv[0][0] == '-' || argv[1][0] == '-')
131 			errx(1, "negative numbers aren't permitted.");
132 
133 		errno = 0;
134 		start = strtoumax(argv[0], &p, 0);
135 		if (errno)
136 			err(1, "%s", argv[0]);
137 		if (*p != '\0')
138 			errx(1, "%s: illegal numeric format.", argv[0]);
139 
140 		errno = 0;
141 		stop = strtoumax(argv[1], &p, 0);
142 		if (errno)
143 			err(1, "%s", argv[1]);
144 		if (*p != '\0')
145 			errx(1, "%s: illegal numeric format.", argv[1]);
146 		break;
147 	case 1:
148 		/* Start on the command line. */
149 		if (argv[0][0] == '-')
150 			errx(1, "negative numbers aren't permitted.");
151 
152 		errno = 0;
153 		start = strtoumax(argv[0], &p, 0);
154 		if (errno)
155 			err(1, "%s", argv[0]);
156 		if (*p != '\0')
157 			errx(1, "%s: illegal numeric format.", argv[0]);
158 		break;
159 	case 0:
160 		start = read_num_buf();
161 		break;
162 	default:
163 		usage();
164 	}
165 
166 	if (start > stop)
167 		errx(1, "start value must be less than stop value.");
168 	primes(start, stop);
169 	return (0);
170 }
171 
172 /*
173  * read_num_buf --
174  *	This routine returns a number n, where 0 <= n && n <= BIG.
175  */
176 static ubig
177 read_num_buf(void)
178 {
179 	ubig val;
180 	char *p, buf[LINE_MAX];		/* > max number of digits. */
181 
182 	for (;;) {
183 		if (fgets(buf, sizeof(buf), stdin) == NULL) {
184 			if (ferror(stdin))
185 				err(1, "stdin");
186 			exit(0);
187 		}
188 		for (p = buf; isblank(*p); ++p);
189 		if (*p == '\n' || *p == '\0')
190 			continue;
191 		if (*p == '-')
192 			errx(1, "negative numbers aren't permitted.");
193 		errno = 0;
194 		val = strtoumax(buf, &p, 0);
195 		if (errno)
196 			err(1, "%s", buf);
197 		if (*p != '\n')
198 			errx(1, "%s: illegal numeric format.", buf);
199 		return (val);
200 	}
201 }
202 
203 /*
204  * primes - sieve and print primes from start up to and but not including stop
205  */
206 static void
207 primes(ubig start, ubig stop)
208 {
209 	char *q;		/* sieve spot */
210 	ubig factor;		/* index and factor */
211 	char *tab_lim;		/* the limit to sieve on the table */
212 	const ubig *p;		/* prime table pointer */
213 	ubig fact_lim;		/* highest prime for current block */
214 	ubig mod;		/* temp storage for mod */
215 
216 	/*
217 	 * A number of systems can not convert double values into unsigned
218 	 * longs when the values are larger than the largest signed value.
219 	 * We don't have this problem, so we can go all the way to BIG.
220 	 */
221 	if (start < 3) {
222 		start = (ubig)2;
223 	}
224 	if (stop < 3) {
225 		stop = (ubig)2;
226 	}
227 	if (stop <= start) {
228 		return;
229 	}
230 
231 	/*
232 	 * be sure that the values are odd, or 2
233 	 */
234 	if (start != 2 && (start&0x1) == 0) {
235 		++start;
236 	}
237 	if (stop != 2 && (stop&0x1) == 0) {
238 		++stop;
239 	}
240 
241 	/*
242 	 * quick list of primes <= pr_limit
243 	 */
244 	if (start <= *pr_limit) {
245 		/* skip primes up to the start value */
246 		for (p = &prime[0], factor = prime[0];
247 		    factor < stop && p <= pr_limit; factor = *(++p)) {
248 			if (factor >= start) {
249 				printf(hflag ? "%" PRIx64 "\n" : "%" PRIu64 "\n", factor);
250 			}
251 		}
252 		/* return early if we are done */
253 		if (p <= pr_limit) {
254 			return;
255 		}
256 		start = *pr_limit+2;
257 	}
258 
259 	/*
260 	 * we shall sieve a bytemap window, note primes and move the window
261 	 * upward until we pass the stop point
262 	 */
263 	while (start < stop) {
264 		/*
265 		 * factor out 3, 5, 7, 11 and 13
266 		 */
267 		/* initial pattern copy */
268 		factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
269 		memcpy(table, &pattern[factor], pattern_size-factor);
270 		/* main block pattern copies */
271 		for (fact_lim=pattern_size-factor;
272 		    fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
273 			memcpy(&table[fact_lim], pattern, pattern_size);
274 		}
275 		/* final block pattern copy */
276 		memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
277 
278 		/*
279 		 * sieve for primes 17 and higher
280 		 */
281 		/* note highest useful factor and sieve spot */
282 		if (stop-start > TABSIZE+TABSIZE) {
283 			tab_lim = &table[TABSIZE]; /* sieve it all */
284 			fact_lim = sqrt(start+1.0+TABSIZE+TABSIZE);
285 		} else {
286 			tab_lim = &table[(stop-start)/2]; /* partial sieve */
287 			fact_lim = sqrt(stop+1.0);
288 		}
289 		/* sieve for factors >= 17 */
290 		factor = 17;	/* 17 is first prime to use */
291 		p = &prime[7];	/* 19 is next prime, pi(19)=7 */
292 		do {
293 			/* determine the factor's initial sieve point */
294 			mod = start%factor;
295 			if (mod & 0x1) {
296 				q = &table[(factor-mod)/2];
297 			} else {
298 				q = &table[mod ? factor-(mod/2) : 0];
299 			}
300 			/* sive for our current factor */
301 			for ( ; q < tab_lim; q += factor) {
302 				*q = '\0'; /* sieve out a spot */
303 			}
304 			factor = *p++;
305 		} while (factor <= fact_lim);
306 
307 		/*
308 		 * print generated primes
309 		 */
310 		for (q = table; q < tab_lim; ++q, start+=2) {
311 			if (*q) {
312 				if (start > SIEVEMAX) {
313 					if (!isprime(start))
314 						continue;
315 				}
316 				printf(hflag ? "%" PRIx64 "\n" : "%" PRIu64 "\n", start);
317 			}
318 		}
319 	}
320 }
321 
322 static void
323 usage(void)
324 {
325 	fprintf(stderr, "usage: primes [-h] [start [stop]]\n");
326 	exit(1);
327 }
328