2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
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16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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38 static const char copyright[] =
39 "@(#) Copyright (c) 1989, 1993\n\
40 The Regents of the University of California. All rights reserved.\n";
45 static char sccsid[] = "@(#)primes.c 8.5 (Berkeley) 5/10/95";
47 static const char rcsid[] =
52 * primes - generate a table of primes between two values
54 * By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
56 * chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
59 * primes [start [stop]]
61 * Print primes >= start and < stop. If stop is omitted,
62 * the value 4294967295 (2^32-1) is assumed. If start is
63 * omitted, start is read from standard input.
65 * validation check: there are 664579 primes between 0 and 10^7
81 * Eratosthenes sieve table
83 * We only sieve the odd numbers. The base of our sieve windows are always
84 * odd. If the base of table is 1, table[i] represents 2*i-1. After the
85 * sieve, table[i] == 1 if and only iff 2*i-1 is prime.
87 * We make TABSIZE large to reduce the overhead of inner loop setup.
89 char table[TABSIZE]; /* Eratosthenes sieve of odd numbers */
92 * prime[i] is the (i-1)th prime.
94 * We are able to sieve 2^32-1 because this byte table yields all primes
95 * up to 65537 and 65537^2 > 2^32-1.
98 extern ubig *pr_limit; /* largest prime in the prime array */
101 * To avoid excessive sieves for small factors, we use the table below to
102 * setup our sieve blocks. Each element represents a odd number starting
103 * with 1. All non-zero elements are factors of 3, 5, 7, 11 and 13.
105 extern char pattern[];
106 extern int pattern_size; /* length of pattern array */
110 void primes __P((ubig, ubig));
111 ubig read_num_buf __P((void));
112 void usage __P((void));
119 ubig start; /* where to start generating */
120 ubig stop; /* don't generate at or above this value */
124 while ((ch = getopt(argc, argv, "h")) != -1)
140 * Convert low and high args. Strtoul(3) sets errno to
141 * ERANGE if the number is too large, but, if there's
142 * a leading minus sign it returns the negation of the
143 * result of the conversion, which we'd rather disallow.
147 /* Start and stop supplied on the command line. */
148 if (argv[0][0] == '-' || argv[1][0] == '-')
149 errx(1, "negative numbers aren't permitted.");
152 start = strtoul(argv[0], &p, 0);
154 err(1, "%s", argv[0]);
156 errx(1, "%s: illegal numeric format.", argv[0]);
159 stop = strtoul(argv[1], &p, 0);
161 err(1, "%s", argv[1]);
163 errx(1, "%s: illegal numeric format.", argv[1]);
166 /* Start on the command line. */
167 if (argv[0][0] == '-')
168 errx(1, "negative numbers aren't permitted.");
171 start = strtoul(argv[0], &p, 0);
173 err(1, "%s", argv[0]);
175 errx(1, "%s: illegal numeric format.", argv[0]);
178 start = read_num_buf();
185 errx(1, "start value must be less than stop value.");
192 * This routine returns a number n, where 0 <= n && n <= BIG.
198 char *p, buf[100]; /* > max number of digits. */
201 if (fgets(buf, sizeof(buf), stdin) == NULL) {
206 for (p = buf; isblank(*p); ++p);
207 if (*p == '\n' || *p == '\0')
210 errx(1, "negative numbers aren't permitted.");
212 val = strtoul(buf, &p, 0);
216 errx(1, "%s: illegal numeric format.", buf);
222 * primes - sieve and print primes from start up to and but not including stop
226 ubig start; /* where to start generating */
227 ubig stop; /* don't generate at or above this value */
229 char *q; /* sieve spot */
230 ubig factor; /* index and factor */
231 char *tab_lim; /* the limit to sieve on the table */
232 ubig *p; /* prime table pointer */
233 ubig fact_lim; /* highest prime for current block */
236 * A number of systems can not convert double values into unsigned
237 * longs when the values are larger than the largest signed value.
238 * We don't have this problem, so we can go all the way to BIG.
251 * be sure that the values are odd, or 2
253 if (start != 2 && (start&0x1) == 0) {
256 if (stop != 2 && (stop&0x1) == 0) {
261 * quick list of primes <= pr_limit
263 if (start <= *pr_limit) {
264 /* skip primes up to the start value */
265 for (p = &prime[0], factor = prime[0];
266 factor < stop && p <= pr_limit; factor = *(++p)) {
267 if (factor >= start) {
268 printf(hflag ? "0x%lx\n" : "%lu\n", factor);
271 /* return early if we are done */
279 * we shall sieve a bytemap window, note primes and move the window
280 * upward until we pass the stop point
282 while (start < stop) {
284 * factor out 3, 5, 7, 11 and 13
286 /* initial pattern copy */
287 factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
288 memcpy(table, &pattern[factor], pattern_size-factor);
289 /* main block pattern copies */
290 for (fact_lim=pattern_size-factor;
291 fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
292 memcpy(&table[fact_lim], pattern, pattern_size);
294 /* final block pattern copy */
295 memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
298 * sieve for primes 17 and higher
300 /* note highest useful factor and sieve spot */
301 if (stop-start > TABSIZE+TABSIZE) {
302 tab_lim = &table[TABSIZE]; /* sieve it all */
303 fact_lim = (int)sqrt(
304 (double)(start)+TABSIZE+TABSIZE+1.0);
306 tab_lim = &table[(stop-start)/2]; /* partial sieve */
307 fact_lim = (int)sqrt((double)(stop)+1.0);
309 /* sieve for factors >= 17 */
310 factor = 17; /* 17 is first prime to use */
311 p = &prime[7]; /* 19 is next prime, pi(19)=7 */
313 /* determine the factor's initial sieve point */
314 q = (char *)(start%factor); /* temp storage for mod */
316 q = &table[(factor-(long)q)/2];
318 q = &table[q ? factor-((long)q/2) : 0];
320 /* sive for our current factor */
321 for ( ; q < tab_lim; q += factor) {
322 *q = '\0'; /* sieve out a spot */
324 } while ((factor=(ubig)(*(p++))) <= fact_lim);
327 * print generated primes
329 for (q = table; q < tab_lim; ++q, start+=2) {
331 printf(hflag ? "0x%lx\n" : "%lu\n", start);
340 (void)fprintf(stderr, "usage: primes [-h] [start [stop]]\n");