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Annotation of OpenXM_contrib/gmp/demos/primes.c, Revision 1.1

1.1     ! maekawa     1: /* List and count primes.
        !             2:
        !             3: Copyright (C) 2000 Free Software Foundation, Inc.
        !             4:
        !             5: This program is free software; you can redistribute it and/or modify it under
        !             6: the terms of the GNU General Public License as published by the Free Software
        !             7: Foundation; either version 2 of the License, or (at your option) any later
        !             8: version.
        !             9:
        !            10: This program is distributed in the hope that it will be useful, but WITHOUT ANY
        !            11: WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
        !            12: PARTICULAR PURPOSE.  See the GNU General Public License for more details.
        !            13:
        !            14: You should have received a copy of the GNU General Public License along with
        !            15: this program; if not, write to the Free Software Foundation, Inc., 59 Temple
        !            16: Place - Suite 330, Boston, MA 02111-1307, USA.  */
        !            17:
        !            18: #include <stdlib.h>
        !            19: #include <stdio.h>
        !            20: #include "gmp.h"
        !            21:
        !            22: /* Sieve table size */
        !            23: #define ST_SIZE 30000
        !            24: /* Largest prime to sieve with */
        !            25: #define MAX_S_PRIME 1000
        !            26:
        !            27: main (int argc, char **argv)
        !            28: {
        !            29:   char *progname = argv[0];
        !            30:   mpz_t r0, r1;                        /* range */
        !            31:   mpz_t cur;
        !            32:   unsigned char *st;
        !            33:   unsigned long i, ii;
        !            34:   unsigned long nprimes = 0;
        !            35:   unsigned long last;
        !            36:   int flag_print = 1;
        !            37:   int flag_count = 0;
        !            38:
        !            39:   st = malloc (ST_SIZE);
        !            40:
        !            41:   while (argc != 1)
        !            42:     {
        !            43:       if (strcmp (argv[1], "-c") == 0)
        !            44:        {
        !            45:          flag_count = 1;
        !            46:          argv++;
        !            47:          argc--;
        !            48:        }
        !            49:       else if (strcmp (argv[1], "-p") == 0)
        !            50:        {
        !            51:          flag_print = 2;
        !            52:          argv++;
        !            53:          argc--;
        !            54:        }
        !            55:       else
        !            56:        break;
        !            57:     }
        !            58:
        !            59:   if (flag_count)
        !            60:     flag_print--;              /* clear unless an explicit -p  */
        !            61:
        !            62:   mpz_init (r0);
        !            63:   mpz_init (r1);
        !            64:   mpz_init (cur);
        !            65:
        !            66:   if (argc == 2)
        !            67:     {
        !            68:       mpz_set_ui (r0, 2);
        !            69:       mpz_set_str (r1, argv[1], 0);
        !            70:     }
        !            71:   else if (argc == 3)
        !            72:     {
        !            73:       mpz_set_str (r0, argv[1], 0);
        !            74:       if (argv[2][0] == '+')
        !            75:        {
        !            76:          mpz_set_str (r1, argv[2] + 1, 0);
        !            77:          mpz_add (r1, r1, r0);
        !            78:        }
        !            79:       else
        !            80:        mpz_set_str (r1, argv[2], 0);
        !            81:     }
        !            82:   else
        !            83:     {
        !            84:       fprintf (stderr, "usage: %s [-c] [-g] [from [+]]to\n", progname);
        !            85:       exit (1);
        !            86:     }
        !            87:
        !            88:   if (mpz_cmp_ui (r0, 2) < 0)
        !            89:     mpz_set_ui (r0, 2);
        !            90:
        !            91:   if ((mpz_get_ui (r0) & 1) == 0)
        !            92:     {
        !            93:       if (mpz_cmp_ui (r0, 2) == 0)
        !            94:        {
        !            95:          if (flag_print)
        !            96:            puts ("2");
        !            97:          nprimes++;
        !            98:        }
        !            99:       mpz_add_ui (r0, r0, 1);
        !           100:     }
        !           101:
        !           102:   mpz_set (cur, r0);
        !           103:
        !           104:   while (mpz_cmp (cur, r1) <= 0)
        !           105:     {
        !           106:       memset (st, 1, ST_SIZE);
        !           107:       for (i = 3; i < MAX_S_PRIME; i += 2)
        !           108:        {
        !           109:          unsigned long start;
        !           110:          start = mpz_tdiv_ui (cur, i);
        !           111:          if (start != 0)
        !           112:            start = i - start;
        !           113:
        !           114:          if (mpz_cmp_ui (cur, i - start) == 0)
        !           115:            start += i;
        !           116:          for (ii = start; ii < ST_SIZE; ii += i)
        !           117:            st[ii] = 0;
        !           118:        }
        !           119:       last = 0;
        !           120:       for (ii = 0; ii < ST_SIZE; ii += 2)
        !           121:        {
        !           122:          if (st[ii] != 0)
        !           123:            {
        !           124:              mpz_add_ui (cur, cur, ii - last);
        !           125:              last = ii;
        !           126:              if (mpz_cmp (cur, r1) > 0)
        !           127:                goto done;
        !           128:              if (mpz_probab_prime_p (cur, 3))
        !           129:                {
        !           130:                  nprimes++;
        !           131:                  if (flag_print)
        !           132:                    {
        !           133:                      mpz_out_str (stdout, 10, cur); puts ("");
        !           134:                    }
        !           135:                }
        !           136:            }
        !           137:        }
        !           138:       mpz_add_ui (cur, cur, ST_SIZE - last);
        !           139:     }
        !           140:  done:
        !           141:   if (flag_count)
        !           142:     printf ("Pi(interval) = %lu\n", nprimes);
        !           143:
        !           144:   exit (0);
        !           145: }