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       1                 :            : /* Determine prime number.
       2                 :            :    Copyright (C) 2006 Red Hat, Inc.
       3                 :            :    This file is part of elfutils.
       4                 :            :    Written by Ulrich Drepper <drepper@redhat.com>, 2000.
       5                 :            : 
       6                 :            :    This file is free software; you can redistribute it and/or modify
       7                 :            :    it under the terms of either
       8                 :            : 
       9                 :            :      * the GNU Lesser General Public License as published by the Free
      10                 :            :        Software Foundation; either version 3 of the License, or (at
      11                 :            :        your option) any later version
      12                 :            : 
      13                 :            :    or
      14                 :            : 
      15                 :            :      * the GNU General Public License as published by the Free
      16                 :            :        Software Foundation; either version 2 of the License, or (at
      17                 :            :        your option) any later version
      18                 :            : 
      19                 :            :    or both in parallel, as here.
      20                 :            : 
      21                 :            :    elfutils is distributed in the hope that it will be useful, but
      22                 :            :    WITHOUT ANY WARRANTY; without even the implied warranty of
      23                 :            :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      24                 :            :    General Public License for more details.
      25                 :            : 
      26                 :            :    You should have received copies of the GNU General Public License and
      27                 :            :    the GNU Lesser General Public License along with this program.  If
      28                 :            :    not, see <http://www.gnu.org/licenses/>.  */
      29                 :            : 
      30                 :            : #include <stddef.h>
      31                 :            : 
      32                 :            : 
      33                 :            : /* Test whether CANDIDATE is a prime.  */
      34                 :            : static int
      35                 :     121502 : is_prime (size_t candidate)
      36                 :            : {
      37                 :            :   /* No even number and none less than 10 will be passed here.  */
      38                 :     121502 :   size_t divn = 3;
      39                 :     121502 :   size_t sq = divn * divn;
      40                 :            : 
      41   [ +  +  +  + ]:     419408 :   while (sq < candidate && candidate % divn != 0)
      42                 :            :     {
      43                 :     297906 :       size_t old_sq = sq;
      44                 :     297906 :       ++divn;
      45                 :     297906 :       sq += 4 * divn;
      46         [ +  - ]:     297906 :       if (sq < old_sq)
      47                 :            :         return 1;
      48                 :     297906 :       ++divn;
      49                 :            :     }
      50                 :            : 
      51                 :     121502 :   return candidate % divn != 0;
      52                 :            : }
      53                 :            : 
      54                 :            : 
      55                 :            : /* We need primes for the table size.  */
      56                 :            : size_t
      57                 :     121402 : next_prime (size_t seed)
      58                 :            : {
      59                 :            :   /* Make it definitely odd.  */
      60                 :     121402 :   seed |= 1;
      61                 :            : 
      62         [ +  + ]:     121502 :   while (!is_prime (seed))
      63                 :        100 :     seed += 2;
      64                 :            : 
      65                 :     121402 :   return seed;
      66                 :            : }