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 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 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 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 336 usage(void) 337 { 338 (void)fprintf(stderr, "usage: primes [-dh] [start [stop]]\n"); 339 exit(1); 340 } 341
Indexes created Sat Sep 20 22:09:52 GMT 2025