games/primes/primes.c

   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  * @(#) Copyright (c) 1989, 1993 The Regents of the University of California.  All rights reserved.
  33  * @(#)primes.c 8.5 (Berkeley) 5/10/95
  34  * $FreeBSD: src/games/primes/primes.c,v 1.15.2.2 2002/10/23 14:59:14 fanf Exp $
  35  * $DragonFly: src/games/primes/primes.c,v 1.2 2003/06/17 04:25:24 dillon Exp $
  36  */
  37
  38 /*
  39  * primes - generate a table of primes between two values
  40  *
  41  * By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
  42  *
  43  * chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
  44  *
  45  * usage:
  46  *      primes [-h] [start [stop]]
  47  *
  48  *      Print primes >= start and < stop.  If stop is omitted,
  49  *      the value 4294967295 (2^32-1) is assumed.  If start is
  50  *      omitted, start is read from standard input.
  51  *
  52  * validation check: there are 664579 primes between 0 and 10^7
  53  */
  54
  55 #include <ctype.h>
  56 #include <err.h>
  57 #include <errno.h>
  58 #include <limits.h>
  59 #include <math.h>
  60 #include <stdio.h>
  61 #include <stdlib.h>
  62 #include <string.h>
  63 #include <unistd.h>
  64
  65 #include "primes.h"
  66
  67 /*
  68  * Eratosthenes sieve table
  69  *
  70  * We only sieve the odd numbers.  The base of our sieve windows are always
  71  * odd.  If the base of table is 1, table[i] represents 2*i-1.  After the
  72  * sieve, table[i] == 1 if and only if 2*i-1 is prime.
  73  *
  74  * We make TABSIZE large to reduce the overhead of inner loop setup.
  75  */
  76 static char table[TABSIZE];      /* Eratosthenes sieve of odd numbers */
  77
  78 static int      hflag;
  79
  80 static void     primes(ubig, ubig);
  81 static ubig     read_num_buf(void);
  82 static void     usage(void);
  83
  84 int
  85 main(int argc, char *argv[])
  86 {
  87         ubig start;             /* where to start generating */
  88         ubig stop;              /* don't generate at or above this value */
  89         int ch;
  90         char *p;
  91
  92         while ((ch = getopt(argc, argv, "h")) != -1)
  93                 switch (ch) {
  94                 case 'h':
  95                         hflag++;
  96                         break;
  97                 case '?':
  98                 default:
  99                         usage();
 100                 }
 101         argc -= optind;
 102         argv += optind;
 103
 104         start = 0;
 105         stop = BIG;
 106
 107         /*
 108          * Convert low and high args.  Strtoul(3) sets errno to
 109          * ERANGE if the number is too large, but, if there's
 110          * a leading minus sign it returns the negation of the
 111          * result of the conversion, which we'd rather disallow.
 112          */
 113         switch (argc) {
 114         case 2:
 115                 /* Start and stop supplied on the command line. */
 116                 if (argv[0][0] == '-' || argv[1][0] == '-')
 117                         errx(1, "negative numbers aren't permitted.");
 118
 119                 errno = 0;
 120                 start = strtoul(argv[0], &p, 0);
 121                 if (errno)
 122                         err(1, "%s", argv[0]);
 123                 if (*p != '\0')
 124                         errx(1, "%s: illegal numeric format.", argv[0]);
 125
 126                 errno = 0;
 127                 stop = strtoul(argv[1], &p, 0);
 128                 if (errno)
 129                         err(1, "%s", argv[1]);
 130                 if (*p != '\0')
 131                         errx(1, "%s: illegal numeric format.", argv[1]);
 132                 break;
 133         case 1:
 134                 /* Start on the command line. */
 135                 if (argv[0][0] == '-')
 136                         errx(1, "negative numbers aren't permitted.");
 137
 138                 errno = 0;
 139                 start = strtoul(argv[0], &p, 0);
 140                 if (errno)
 141                         err(1, "%s", argv[0]);
 142                 if (*p != '\0')
 143                         errx(1, "%s: illegal numeric format.", argv[0]);
 144                 break;
 145         case 0:
 146                 start = read_num_buf();
 147                 break;
 148         default:
 149                 usage();
 150         }
 151
 152         if (start > stop)
 153                 errx(1, "start value must be less than stop value.");
 154         primes(start, stop);
 155         return (0);
 156 }
 157
 158 /*
 159  * read_num_buf --
 160  *      This routine returns a number n, where 0 <= n && n <= BIG.
 161  */
 162 static ubig
 163 read_num_buf(void)
 164 {
 165         ubig val;
 166         char *p, buf[LINE_MAX];         /* > max number of digits. */
 167
 168         for (;;) {
 169                 if (fgets(buf, sizeof(buf), stdin) == NULL) {
 170                         if (ferror(stdin))
 171                                 err(1, "stdin");
 172                         exit(0);
 173                 }
 174                 for (p = buf; isblank(*p); ++p);
 175                 if (*p == '\n' || *p == '\0')
 176                         continue;
 177                 if (*p == '-')
 178                         errx(1, "negative numbers aren't permitted.");
 179                 errno = 0;
 180                 val = strtoul(buf, &p, 0);
 181                 if (errno)
 182                         err(1, "%s", buf);
 183                 if (*p != '\n')
 184                         errx(1, "%s: illegal numeric format.", buf);
 185                 return (val);
 186         }
 187 }
 188
 189 /*
 190  * primes - sieve and print primes from start up to and but not including stop
 191  */
 192 static void
 193 primes(ubig start, ubig stop)
 194 {
 195         char *q;                /* sieve spot */
 196         ubig factor;            /* index and factor */
 197         char *tab_lim;          /* the limit to sieve on the table */
 198         const ubig *p;          /* prime table pointer */
 199         ubig fact_lim;          /* highest prime for current block */
 200         ubig mod;               /* temp storage for mod */
 201
 202         /*
 203          * A number of systems can not convert double values into unsigned
 204          * longs when the values are larger than the largest signed value.
 205          * We don't have this problem, so we can go all the way to BIG.
 206          */
 207         if (start < 3) {
 208                 start = (ubig)2;
 209         }
 210         if (stop < 3) {
 211                 stop = (ubig)2;
 212         }
 213         if (stop <= start) {
 214                 return;
 215         }
 216
 217         /*
 218          * be sure that the values are odd, or 2
 219          */
 220         if (start != 2 && (start&0x1) == 0) {
 221                 ++start;
 222         }
 223         if (stop != 2 && (stop&0x1) == 0) {
 224                 ++stop;
 225         }
 226
 227         /*
 228          * quick list of primes <= pr_limit
 229          */
 230         if (start <= *pr_limit) {
 231                 /* skip primes up to the start value */
 232                 for (p = &prime[0], factor = prime[0];
 233                     factor < stop && p <= pr_limit; factor = *(++p)) {
 234                         if (factor >= start) {
 235                                 printf(hflag ? "0x%lx\n" : "%lu\n", factor);
 236                         }
 237                 }
 238                 /* return early if we are done */
 239                 if (p <= pr_limit) {
 240                         return;
 241                 }
 242                 start = *pr_limit+2;
 243         }
 244
 245         /*
 246          * we shall sieve a bytemap window, note primes and move the window
 247          * upward until we pass the stop point
 248          */
 249         while (start < stop) {
 250                 /*
 251                  * factor out 3, 5, 7, 11 and 13
 252                  */
 253                 /* initial pattern copy */
 254                 factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
 255                 memcpy(table, &pattern[factor], pattern_size-factor);
 256                 /* main block pattern copies */
 257                 for (fact_lim=pattern_size-factor;
 258                     fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
 259                         memcpy(&table[fact_lim], pattern, pattern_size);
 260                 }
 261                 /* final block pattern copy */
 262                 memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
 263
 264                 /*
 265                  * sieve for primes 17 and higher
 266                  */
 267                 /* note highest useful factor and sieve spot */
 268                 if (stop-start > TABSIZE+TABSIZE) {
 269                         tab_lim = &table[TABSIZE]; /* sieve it all */
 270                         fact_lim = sqrt(start+1.0+TABSIZE+TABSIZE);
 271                 } else {
 272                         tab_lim = &table[(stop-start)/2]; /* partial sieve */
 273                         fact_lim = sqrt(stop+1.0);
 274                 }
 275                 /* sieve for factors >= 17 */
 276                 factor = 17;    /* 17 is first prime to use */
 277                 p = &prime[7];  /* 19 is next prime, pi(19)=7 */
 278                 do {
 279                         /* determine the factor's initial sieve point */
 280                         mod = start%factor;
 281                         if (mod & 0x1) {
 282                                 q = &table[(factor-mod)/2];
 283                         } else {
 284                                 q = &table[mod ? factor-(mod/2) : 0];
 285                         }
 286                         /* sive for our current factor */
 287                         for ( ; q < tab_lim; q += factor) {
 288                                 *q = '\0'; /* sieve out a spot */
 289                         }
 290                         factor = *p++;
 291                 } while (factor <= fact_lim);
 292
 293                 /*
 294                  * print generated primes
 295                  */
 296                 for (q = table; q < tab_lim; ++q, start+=2) {
 297                         if (*q) {
 298                                 printf(hflag ? "0x%lx\n" : "%lu\n", start);
 299                         }
 300                 }
 301         }
 302 }
 303
 304 static void
 305 usage(void)
 306 {
 307         fprintf(stderr, "usage: primes [-h] [start [stop]]\n");
 308         exit(1);
 309 }