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/* Test mpz_powm, mpz_lucas_mod.
Copyright 1991, 1993, 1994, 1996, 1999-2001, 2009, 2012, 2018 Free Software
Foundation, Inc.
This file is part of the GNU MP Library test suite.
The GNU MP Library test suite is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 3 of the License,
or (at your option) any later version.
The GNU MP Library test suite 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 General
Public License for more details.
You should have received a copy of the GNU General Public License along with
the GNU MP Library test suite. If not, see https://www.gnu.org/licenses/. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "gmp-impl.h"
#include "tests.h"
void debug_mp (mpz_t, int);
#define SIZEM 8
/* FIXME: Should we implement another sequence to test lucas mod? */
/* Eg: a generalisation of what we use for Fibonacci: */
/* U_{2n-1} = U_n^2 - Q*U_{n-1}^2 */
/* U_{2n+1} = D*U_n^2 + Q*U_{2n-1} + 2*Q^n ; whith D = (P^2-4*Q) */
/* P*U_{2n} = U_{2n+1} + Q*U_{2n-1} */
int
main (int argc, char **argv)
{
mpz_t base, exp, mod;
mpz_t r1, r2, t1, t2;
mp_size_t base_size, exp_size, mod_size;
int i, res;
int reps = 1000;
long Q;
gmp_randstate_ptr rands;
mpz_t bs;
unsigned long bsi, size_range;
tests_start ();
TESTS_REPS (reps, argv, argc);
rands = RANDS;
mpz_init (bs);
mpz_init (base);
mpz_init (exp);
mpz_init (mod);
mpz_init (r1);
mpz_init (r2);
mpz_init (t1);
mpz_init (t2);
for (i = 0; i < reps; i++)
{
mpz_urandomb (bs, rands, 32);
size_range = mpz_get_ui (bs) % SIZEM + 1;
do /* Loop until base >= 2 and fits in a long. */
{
mpz_urandomb (base, rands, BITS_PER_ULONG - 2);
}
while (mpz_cmp_ui (base, 2) < 0 || mpz_fits_slong_p (base) == 0);
Q = mpz_get_ui (base);
do
{
++size_range;
size_range = MIN (size_range, SIZEM);
mpz_urandomb (bs, rands, size_range);
mod_size = mpz_get_ui (bs);
mpz_rrandomb (mod, rands, mod_size);
mpz_add_ui (mod, mod, 16);
}
while (mpz_gcd_ui (NULL, mod, Q) != 1);
mod_size = mpz_sizeinbase (mod, 2) - 3;
mpz_urandomb (bs, rands, 32);
exp_size = mpz_get_ui (bs) % mod_size + 2;
mpz_tdiv_q_2exp (exp, mod, exp_size);
mpz_add_ui (exp, exp, 1);
mpz_urandomb (bs, rands, 2);
bsi = mpz_get_ui (bs);
if ((bsi & 1) != 0)
{
mpz_neg (base, base);
Q = -Q;
}
res = mpz_lucas_mod (t1, r2, Q, exp_size, mod, t2, r1);
if (res && ++reps)
continue;
MPZ_CHECK_FORMAT (r2);
if (mpz_cmp_ui (r2, 0) < 0)
mpz_add (r2, r2, mod);
mpz_powm (r1, base, exp, mod);
if (mpz_cmp (r1, r2) != 0)
{
fprintf (stderr, "\nIncorrect results in test %d for operands:\n", i);
debug_mp (base, -16);
debug_mp (exp, -16);
debug_mp (mod, -16);
fprintf (stderr, "mpz_powm result:\n");
debug_mp (r1, -16);
fprintf (stderr, "mpz_lucas_mod result (%d) Q=%ld:\n", res, Q);
debug_mp (r2, -16);
abort ();
}
}
mpz_clear (bs);
mpz_clear (base);
mpz_clear (exp);
mpz_clear (mod);
mpz_clear (r1);
mpz_clear (r2);
mpz_clear (t1);
mpz_clear (t2);
tests_end ();
exit (0);
}
void
debug_mp (mpz_t x, int base)
{
mpz_out_str (stderr, base, x); fputc ('\n', stderr);
}
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