xref: /freebsd/usr.bin/primes/primes.c (revision bdcbfde31e8e9b343f113a1956384bdf30d1ed62)
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 #endif /* not lint */
41 
42 /*
43  * primes - generate a table of primes between two values
44  *
45  * By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
46  *
47  * chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
48  *
49  * usage:
50  *	primes [-h] [start [stop]]
51  *
52  *	Print primes >= start and < stop.  If stop is omitted,
53  *	the value 18446744073709551615 (2^64-1) is assumed.  If
54  *	start is omitted, start is read from standard input.
55  *
56  * validation check: there are 664579 primes between 0 and 10^7
57  */
58 
59 #include <capsicum_helpers.h>
60 #include <ctype.h>
61 #include <err.h>
62 #include <errno.h>
63 #include <inttypes.h>
64 #include <limits.h>
65 #include <math.h>
66 #include <stdio.h>
67 #include <stdlib.h>
68 #include <string.h>
69 #include <nl_types.h>
70 #include <unistd.h>
71 
72 #include "primes.h"
73 
74 /*
75  * Eratosthenes sieve table
76  *
77  * We only sieve the odd numbers.  The base of our sieve windows are always
78  * odd.  If the base of table is 1, table[i] represents 2*i-1.  After the
79  * sieve, table[i] == 1 if and only if 2*i-1 is prime.
80  *
81  * We make TABSIZE large to reduce the overhead of inner loop setup.
82  */
83 static char table[TABSIZE];	 /* Eratosthenes sieve of odd numbers */
84 
85 static int	hflag;
86 
87 static void	primes(ubig, ubig);
88 static ubig	read_num_buf(void);
89 static void	usage(void);
90 
91 int
92 main(int argc, char *argv[])
93 {
94 	ubig start;		/* where to start generating */
95 	ubig stop;		/* don't generate at or above this value */
96 	int ch;
97 	char *p;
98 
99 	caph_cache_catpages();
100 	if (caph_enter() < 0)
101 		err(1, "cap_enter");
102 
103 	while ((ch = getopt(argc, argv, "h")) != -1)
104 		switch (ch) {
105 		case 'h':
106 			hflag++;
107 			break;
108 		case '?':
109 		default:
110 			usage();
111 		}
112 	argc -= optind;
113 	argv += optind;
114 
115 	start = 0;
116 	stop = (uint64_t)(-1);
117 
118 	/*
119 	 * Convert low and high args.  Strtoumax(3) sets errno to
120 	 * ERANGE if the number is too large, but, if there's
121 	 * a leading minus sign it returns the negation of the
122 	 * result of the conversion, which we'd rather disallow.
123 	 */
124 	switch (argc) {
125 	case 2:
126 		/* Start and stop supplied on the command line. */
127 		if (argv[0][0] == '-' || argv[1][0] == '-')
128 			errx(1, "negative numbers aren't permitted.");
129 
130 		errno = 0;
131 		start = strtoumax(argv[0], &p, 0);
132 		if (errno)
133 			err(1, "%s", argv[0]);
134 		if (*p != '\0')
135 			errx(1, "%s: illegal numeric format.", argv[0]);
136 
137 		errno = 0;
138 		stop = strtoumax(argv[1], &p, 0);
139 		if (errno)
140 			err(1, "%s", argv[1]);
141 		if (*p != '\0')
142 			errx(1, "%s: illegal numeric format.", argv[1]);
143 		break;
144 	case 1:
145 		/* Start on the command line. */
146 		if (argv[0][0] == '-')
147 			errx(1, "negative numbers aren't permitted.");
148 
149 		errno = 0;
150 		start = strtoumax(argv[0], &p, 0);
151 		if (errno)
152 			err(1, "%s", argv[0]);
153 		if (*p != '\0')
154 			errx(1, "%s: illegal numeric format.", argv[0]);
155 		break;
156 	case 0:
157 		start = read_num_buf();
158 		break;
159 	default:
160 		usage();
161 	}
162 
163 	if (start > stop)
164 		errx(1, "start value must be less than stop value.");
165 	primes(start, stop);
166 	return (0);
167 }
168 
169 /*
170  * read_num_buf --
171  *	This routine returns a number n, where 0 <= n && n <= BIG.
172  */
173 static ubig
174 read_num_buf(void)
175 {
176 	ubig val;
177 	char *p, buf[LINE_MAX];		/* > max number of digits. */
178 
179 	for (;;) {
180 		if (fgets(buf, sizeof(buf), stdin) == NULL) {
181 			if (ferror(stdin))
182 				err(1, "stdin");
183 			exit(0);
184 		}
185 		for (p = buf; isblank(*p); ++p);
186 		if (*p == '\n' || *p == '\0')
187 			continue;
188 		if (*p == '-')
189 			errx(1, "negative numbers aren't permitted.");
190 		errno = 0;
191 		val = strtoumax(buf, &p, 0);
192 		if (errno)
193 			err(1, "%s", buf);
194 		if (*p != '\n')
195 			errx(1, "%s: illegal numeric format.", buf);
196 		return (val);
197 	}
198 }
199 
200 /*
201  * primes - sieve and print primes from start up to and but not including stop
202  */
203 static void
204 primes(ubig start, ubig stop)
205 {
206 	char *q;		/* sieve spot */
207 	ubig factor;		/* index and factor */
208 	char *tab_lim;		/* the limit to sieve on the table */
209 	const ubig *p;		/* prime table pointer */
210 	ubig fact_lim;		/* highest prime for current block */
211 	ubig mod;		/* temp storage for mod */
212 
213 	/*
214 	 * A number of systems can not convert double values into unsigned
215 	 * longs when the values are larger than the largest signed value.
216 	 * We don't have this problem, so we can go all the way to BIG.
217 	 */
218 	if (start < 3) {
219 		start = (ubig)2;
220 	}
221 	if (stop < 3) {
222 		stop = (ubig)2;
223 	}
224 	if (stop <= start) {
225 		return;
226 	}
227 
228 	/*
229 	 * be sure that the values are odd, or 2
230 	 */
231 	if (start != 2 && (start&0x1) == 0) {
232 		++start;
233 	}
234 	if (stop != 2 && (stop&0x1) == 0) {
235 		++stop;
236 	}
237 
238 	/*
239 	 * quick list of primes <= pr_limit
240 	 */
241 	if (start <= *pr_limit) {
242 		/* skip primes up to the start value */
243 		for (p = &prime[0], factor = prime[0];
244 		    factor < stop && p <= pr_limit; factor = *(++p)) {
245 			if (factor >= start) {
246 				printf(hflag ? "%" PRIx64 "\n" : "%" PRIu64 "\n", factor);
247 			}
248 		}
249 		/* return early if we are done */
250 		if (p <= pr_limit) {
251 			return;
252 		}
253 		start = *pr_limit+2;
254 	}
255 
256 	/*
257 	 * we shall sieve a bytemap window, note primes and move the window
258 	 * upward until we pass the stop point
259 	 */
260 	while (start < stop) {
261 		/*
262 		 * factor out 3, 5, 7, 11 and 13
263 		 */
264 		/* initial pattern copy */
265 		factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
266 		memcpy(table, &pattern[factor], pattern_size-factor);
267 		/* main block pattern copies */
268 		for (fact_lim=pattern_size-factor;
269 		    fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
270 			memcpy(&table[fact_lim], pattern, pattern_size);
271 		}
272 		/* final block pattern copy */
273 		memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
274 
275 		/*
276 		 * sieve for primes 17 and higher
277 		 */
278 		/* note highest useful factor and sieve spot */
279 		if (stop-start > TABSIZE+TABSIZE) {
280 			tab_lim = &table[TABSIZE]; /* sieve it all */
281 			fact_lim = sqrt(start+1.0+TABSIZE+TABSIZE);
282 		} else {
283 			tab_lim = &table[(stop-start)/2]; /* partial sieve */
284 			fact_lim = sqrt(stop+1.0);
285 		}
286 		/* sieve for factors >= 17 */
287 		factor = 17;	/* 17 is first prime to use */
288 		p = &prime[7];	/* 19 is next prime, pi(19)=7 */
289 		do {
290 			/* determine the factor's initial sieve point */
291 			mod = start%factor;
292 			if (mod & 0x1) {
293 				q = &table[(factor-mod)/2];
294 			} else {
295 				q = &table[mod ? factor-(mod/2) : 0];
296 			}
297 			/* sive for our current factor */
298 			for ( ; q < tab_lim; q += factor) {
299 				*q = '\0'; /* sieve out a spot */
300 			}
301 			factor = *p++;
302 		} while (factor <= fact_lim);
303 
304 		/*
305 		 * print generated primes
306 		 */
307 		for (q = table; q < tab_lim; ++q, start+=2) {
308 			if (*q) {
309 				if (start > SIEVEMAX) {
310 					if (!isprime(start))
311 						continue;
312 				}
313 				printf(hflag ? "%" PRIx64 "\n" : "%" PRIu64 "\n", start);
314 			}
315 		}
316 	}
317 }
318 
319 static void
320 usage(void)
321 {
322 	fprintf(stderr, "usage: primes [-h] [start [stop]]\n");
323 	exit(1);
324 }
325