1 /* Determine prime number. 2 Copyright (C) 2006 Red Hat, Inc. 3 This file is part of elfutils. 4 Written by Ulrich Drepper <drepper (at) 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 is_prime (size_t candidate) 36 { 37 /* No even number and none less than 10 will be passed here. */ 38 size_t divn = 3; 39 size_t sq = divn * divn; 40 41 while (sq < candidate && candidate % divn != 0) 42 { 43 size_t old_sq = sq; 44 ++divn; 45 sq += 4 * divn; 46 if (sq < old_sq) 47 return 1; 48 ++divn; 49 } 50 51 return candidate % divn != 0; 52 } 53 54 55 /* We need primes for the table size. */ 56 size_t 57 next_prime (size_t seed) 58 { 59 /* Make it definitely odd. */ 60 seed |= 1; 61 62 while (!is_prime (seed)) 63 seed += 2; 64 65 return seed; 66 } 67
