1 /* mpz_nextprime(p,t) - compute the next prime > t and store that in p.
3 Copyright (C) 1999, 2000 Free Software Foundation, Inc.
5 This file is part of the GNU MP Library.
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 2.1 of the License, or (at your
10 option) any later version.
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with the GNU MP Library; see the file COPYING.LIB. If not, write to
19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20 MA 02111-1307, USA. */
27 mpz_nextprime (mpz_ptr p, mpz_srcptr t)
34 mpz_add_ui (p, t, 1L);
35 while (! mpz_probab_prime_p (p, 5))
36 mpz_add_ui (p, p, 1L);
40 /* This code is not yet tested. Will be enabled in 3.1. */
42 status unsigned short primes[] =
44 3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,
45 101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,
46 191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,
47 281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,
48 389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,
49 491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,
50 607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,
51 719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,
52 829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,
53 953,967,971,977,983,991,997
56 #define NUMBER_OF_PRIMES 167
60 mpz_nextprime (mpz_ptr p, mpz_srcptr n)
68 unsigned short *moduli;
69 unsigned long difference;
73 /* First handle tiny numbers */
74 if (mpz_cmp_ui (n, 2) < 0)
82 if (mpz_cmp_ui (p, 7) <= 0)
85 prime_limit = NUMBER_OF_PRIMES - 1;
86 if (mpz_cmp_ui (p, primes[prime_limit]) <= 0)
87 /* Just use first three entries (3,5,7) of table for small numbers */
91 /* Compute residues modulo small odd primes */
92 moduli = (unsigned short *) TMP_ALLOC (prime_limit * sizeof moduli[0]);
93 for (i = 0; i < prime_limit; i++)
94 moduli[i] = mpz_fdiv_ui (p, primes[i]);
96 for (difference = 0; ; difference += 2)
100 /* First check residues */
101 for (i = 0; i < prime_limit; i++)
104 composite |= (moduli[i] == 0);
107 moduli[i] = acc >= pr ? acc - pr : acc;
112 mpz_add_ui (p, p, difference);
115 /* Miller-Rabin test */
116 if (mpz_millerrabin (p, 2))