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. 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.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#) Copyright (c) 1989, 1993 The Regents of the University of California.  All rights reserved.
  37  * @(#)primes.c 8.5 (Berkeley) 5/10/95
  38  * $FreeBSD: src/games/primes/primes.c,v 1.15.2.2 2002/10/23 14:59:14 fanf Exp $
  39  * $DragonFly: src/games/primes/primes.c,v 1.2 2003/06/17 04:25:24 dillon Exp $
  40  */
  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 4294967295 (2^32-1) is assumed.  If start is
  54  *      omitted, start is read from standard input.
  55  *
  56  * validation check: there are 664579 primes between 0 and 10^7
  57  */
  58
  59 #include <ctype.h>
  60 #include <err.h>
  61 #include <errno.h>
  62 #include <limits.h>
  63 #include <math.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include "primes.h"
  70
  71 /*
  72  * Eratosthenes sieve table
  73  *
  74  * We only sieve the odd numbers.  The base of our sieve windows are always
  75  * odd.  If the base of table is 1, table[i] represents 2*i-1.  After the
  76  * sieve, table[i] == 1 if and only if 2*i-1 is prime.
  77  *
  78  * We make TABSIZE large to reduce the overhead of inner loop setup.
  79  */
  80 static char table[TABSIZE];      /* Eratosthenes sieve of odd numbers */
  81
  82 static int      hflag;
  83
  84 static void     primes(ubig, ubig);
  85 static ubig     read_num_buf(void);
  86 static void     usage(void);
  87
  88 int
  89 main(int argc, char *argv[])
  90 {
  91         ubig start;             /* where to start generating */
  92         ubig stop;              /* don't generate at or above this value */
  93         int ch;
  94         char *p;
  95
  96         while ((ch = getopt(argc, argv, "h")) != -1)
  97                 switch (ch) {
  98                 case 'h':
  99                         hflag++;
 100                         break;
 101                 case '?':
 102                 default:
 103                         usage();
 104                 }
 105         argc -= optind;
 106         argv += optind;
 107
 108         start = 0;
 109         stop = BIG;
 110
 111         /*
 112          * Convert low and high args.  Strtoul(3) sets errno to
 113          * ERANGE if the number is too large, but, if there's
 114          * a leading minus sign it returns the negation of the
 115          * result of the conversion, which we'd rather disallow.
 116          */
 117         switch (argc) {
 118         case 2:
 119                 /* Start and stop supplied on the command line. */
 120                 if (argv[0][0] == '-' || argv[1][0] == '-')
 121                         errx(1, "negative numbers aren't permitted.");
 122
 123                 errno = 0;
 124                 start = strtoul(argv[0], &p, 0);
 125                 if (errno)
 126                         err(1, "%s", argv[0]);
 127                 if (*p != '\0')
 128                         errx(1, "%s: illegal numeric format.", argv[0]);
 129
 130                 errno = 0;
 131                 stop = strtoul(argv[1], &p, 0);
 132                 if (errno)
 133                         err(1, "%s", argv[1]);
 134                 if (*p != '\0')
 135                         errx(1, "%s: illegal numeric format.", argv[1]);
 136                 break;
 137         case 1:
 138                 /* Start on the command line. */
 139                 if (argv[0][0] == '-')
 140                         errx(1, "negative numbers aren't permitted.");
 141
 142                 errno = 0;
 143                 start = strtoul(argv[0], &p, 0);
 144                 if (errno)
 145                         err(1, "%s", argv[0]);
 146                 if (*p != '\0')
 147                         errx(1, "%s: illegal numeric format.", argv[0]);
 148                 break;
 149         case 0:
 150                 start = read_num_buf();
 151                 break;
 152         default:
 153                 usage();
 154         }
 155
 156         if (start > stop)
 157                 errx(1, "start value must be less than stop value.");
 158         primes(start, stop);
 159         return (0);
 160 }
 161
 162 /*
 163  * read_num_buf --
 164  *      This routine returns a number n, where 0 <= n && n <= BIG.
 165  */
 166 static ubig
 167 read_num_buf(void)
 168 {
 169         ubig val;
 170         char *p, buf[LINE_MAX];         /* > max number of digits. */
 171
 172         for (;;) {
 173                 if (fgets(buf, sizeof(buf), stdin) == NULL) {
 174                         if (ferror(stdin))
 175                                 err(1, "stdin");
 176                         exit(0);
 177                 }
 178                 for (p = buf; isblank(*p); ++p);
 179                 if (*p == '\n' || *p == '\0')
 180                         continue;
 181                 if (*p == '-')
 182                         errx(1, "negative numbers aren't permitted.");
 183                 errno = 0;
 184                 val = strtoul(buf, &p, 0);
 185                 if (errno)
 186                         err(1, "%s", buf);
 187                 if (*p != '\n')
 188                         errx(1, "%s: illegal numeric format.", buf);
 189                 return (val);
 190         }
 191 }
 192
 193 /*
 194  * primes - sieve and print primes from start up to and but not including stop
 195  */
 196 static void
 197 primes(ubig start, ubig stop)
 198 {
 199         char *q;                /* sieve spot */
 200         ubig factor;            /* index and factor */
 201         char *tab_lim;          /* the limit to sieve on the table */
 202         const ubig *p;          /* prime table pointer */
 203         ubig fact_lim;          /* highest prime for current block */
 204         ubig mod;               /* temp storage for mod */
 205
 206         /*
 207          * A number of systems can not convert double values into unsigned
 208          * longs when the values are larger than the largest signed value.
 209          * We don't have this problem, so we can go all the way to BIG.
 210          */
 211         if (start < 3) {
 212                 start = (ubig)2;
 213         }
 214         if (stop < 3) {
 215                 stop = (ubig)2;
 216         }
 217         if (stop <= start) {
 218                 return;
 219         }
 220
 221         /*
 222          * be sure that the values are odd, or 2
 223          */
 224         if (start != 2 && (start&0x1) == 0) {
 225                 ++start;
 226         }
 227         if (stop != 2 && (stop&0x1) == 0) {
 228                 ++stop;
 229         }
 230
 231         /*
 232          * quick list of primes <= pr_limit
 233          */
 234         if (start <= *pr_limit) {
 235                 /* skip primes up to the start value */
 236                 for (p = &prime[0], factor = prime[0];
 237                     factor < stop && p <= pr_limit; factor = *(++p)) {
 238                         if (factor >= start) {
 239                                 printf(hflag ? "0x%lx\n" : "%lu\n", factor);
 240                         }
 241                 }
 242                 /* return early if we are done */
 243                 if (p <= pr_limit) {
 244                         return;
 245                 }
 246                 start = *pr_limit+2;
 247         }
 248
 249         /*
 250          * we shall sieve a bytemap window, note primes and move the window
 251          * upward until we pass the stop point
 252          */
 253         while (start < stop) {
 254                 /*
 255                  * factor out 3, 5, 7, 11 and 13
 256                  */
 257                 /* initial pattern copy */
 258                 factor = (start%(2*3*5*7*11*13))/2; /* starting copy spot */
 259                 memcpy(table, &pattern[factor], pattern_size-factor);
 260                 /* main block pattern copies */
 261                 for (fact_lim=pattern_size-factor;
 262                     fact_lim+pattern_size<=TABSIZE; fact_lim+=pattern_size) {
 263                         memcpy(&table[fact_lim], pattern, pattern_size);
 264                 }
 265                 /* final block pattern copy */
 266                 memcpy(&table[fact_lim], pattern, TABSIZE-fact_lim);
 267
 268                 /*
 269                  * sieve for primes 17 and higher
 270                  */
 271                 /* note highest useful factor and sieve spot */
 272                 if (stop-start > TABSIZE+TABSIZE) {
 273                         tab_lim = &table[TABSIZE]; /* sieve it all */
 274                         fact_lim = sqrt(start+1.0+TABSIZE+TABSIZE);
 275                 } else {
 276                         tab_lim = &table[(stop-start)/2]; /* partial sieve */
 277                         fact_lim = sqrt(stop+1.0);
 278                 }
 279                 /* sieve for factors >= 17 */
 280                 factor = 17;    /* 17 is first prime to use */
 281                 p = &prime[7];  /* 19 is next prime, pi(19)=7 */
 282                 do {
 283                         /* determine the factor's initial sieve point */
 284                         mod = start%factor;
 285                         if (mod & 0x1) {
 286                                 q = &table[(factor-mod)/2];
 287                         } else {
 288                                 q = &table[mod ? factor-(mod/2) : 0];
 289                         }
 290                         /* sive for our current factor */
 291                         for ( ; q < tab_lim; q += factor) {
 292                                 *q = '\0'; /* sieve out a spot */
 293                         }
 294                         factor = *p++;
 295                 } while (factor <= fact_lim);
 296
 297                 /*
 298                  * print generated primes
 299                  */
 300                 for (q = table; q < tab_lim; ++q, start+=2) {
 301                         if (*q) {
 302                                 printf(hflag ? "0x%lx\n" : "%lu\n", start);
 303                         }
 304                 }
 305         }
 306 }
 307
 308 static void
 309 usage(void)
 310 {
 311         fprintf(stderr, "usage: primes [-h] [start [stop]]\n");
 312         exit(1);
 313 }