133 lines
3.5 KiB
C
133 lines
3.5 KiB
C
/* mpz_next_prime_candidate(p,t,rnd) - compute the next likely prime > t and store that in p.
|
|
|
|
Copyright 1999, 2000, 2001 Free Software Foundation, Inc.
|
|
Copyright 2009 Jason Moxham, Brian Gladman
|
|
|
|
This file is part of the MPIR Library.
|
|
|
|
The MPIR Library is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as published
|
|
by the Free Software Foundation; either version 2.1 of the License, or (at
|
|
your option) any later version.
|
|
|
|
The MPIR Library is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
|
|
License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with the MPIR Library; see the file COPYING.LIB. If not, write
|
|
to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
|
|
Boston, MA 02110-1301, USA.
|
|
*/
|
|
|
|
#include "mpir.h"
|
|
#include "gmp-impl.h"
|
|
|
|
#if 0
|
|
|
|
void
|
|
mpz_next_prime_candidate (mpz_ptr p, mpz_srcptr t, gmp_randstate_t rnd)
|
|
{
|
|
mpz_add_ui (p, t, 1L);
|
|
while (! mpz_likely_prime_p (p, rnd,0))
|
|
mpz_add_ui (p, p, 1L);
|
|
}
|
|
|
|
#else
|
|
|
|
/* This code is not yet tested. Will be enabled some time. */
|
|
|
|
static unsigned short primes[] =
|
|
{
|
|
3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,
|
|
101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,
|
|
191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,
|
|
281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,
|
|
389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,
|
|
491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,
|
|
607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,
|
|
719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,
|
|
829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,
|
|
953,967,971,977,983,991,997
|
|
};
|
|
|
|
#define NUMBER_OF_PRIMES (sizeof(primes) / sizeof(primes[0]))
|
|
|
|
void
|
|
mpz_next_prime_candidate (mpz_ptr p, mpz_srcptr n, gmp_randstate_t rnd)
|
|
{
|
|
unsigned short *moduli;
|
|
unsigned long difference;
|
|
int i, prime_limit;
|
|
int composite;
|
|
TMP_DECL;
|
|
|
|
/* First handle tiny numbers */
|
|
if (mpz_cmp_ui (n, 2) < 0)
|
|
{
|
|
mpz_set_ui (p, 2);
|
|
return;
|
|
}
|
|
mpz_add_ui (p, n, 1);
|
|
mpz_setbit (p, 0);
|
|
|
|
if (mpz_cmp_ui (p, 7) <= 0)
|
|
return;
|
|
|
|
prime_limit = NUMBER_OF_PRIMES - 1;
|
|
if (mpz_cmp_ui (p, primes[prime_limit]) <= 0)
|
|
{
|
|
int lo = 0, hi = NUMBER_OF_PRIMES - 1, mid;
|
|
|
|
i = mpz_get_ui(p);
|
|
while(lo <= hi)
|
|
{
|
|
mid = lo + (hi - lo) / 2;
|
|
if(i > primes[mid])
|
|
lo = mid + 1;
|
|
else if(i < primes[mid])
|
|
hi = mid - 1;
|
|
else
|
|
{
|
|
lo = mid;
|
|
break;
|
|
}
|
|
}
|
|
mpz_set_ui(p, primes[lo]);
|
|
return;
|
|
}
|
|
|
|
TMP_MARK;
|
|
/* Compute residues modulo small odd primes */
|
|
moduli = (unsigned short *) TMP_ALLOC (prime_limit * sizeof moduli[0]);
|
|
for (i = 0; i < prime_limit; i++)
|
|
moduli[i] = mpz_fdiv_ui (p, primes[i]);
|
|
for (difference = 0; ; difference += 2)
|
|
{
|
|
composite = 0;
|
|
|
|
/* First check residues */
|
|
for (i = 0; i < prime_limit; i++)
|
|
{
|
|
int acc, pr;
|
|
composite |= (moduli[i] == 0);
|
|
acc = moduli[i] + 2;
|
|
pr = primes[i];
|
|
moduli[i] = acc >= pr ? acc - pr : acc;
|
|
}
|
|
if (composite)
|
|
continue;
|
|
|
|
mpz_add_ui (p, p, difference);
|
|
difference = 0;
|
|
|
|
/* Miller-Rabin test */
|
|
if (mpz_miller_rabin (p, 2, rnd))
|
|
break;
|
|
}
|
|
TMP_FREE;
|
|
}
|
|
|
|
#endif
|