mp_limb_t
n_powmod_precomp(mp_limb_t a, mp_limb_signed_t exp, mp_limb_t n, double npre)
{
mp_limb_t x, y;
mp_limb_signed_t e;
if (n == 1UL)
return 0L;
e = (exp < 0L ? -exp : exp);
x = 1UL;
y = a;
while (e)
{
if (e & 1L)
x = n_mulmod_precomp(x, y, n, npre);
e >>= 1;
if (e)
y = n_mulmod_precomp(y, y, n, npre);
}
return (exp < 0L ? n_invmod(x, n) : x);
}
int
n_is_probabprime_fibonacci(mp_limb_t n)
{
mp_limb_t m;
n_pair_t V;
if (FLINT_ABS((mp_limb_signed_t) n) <= 3UL)
{
if (n >= 2UL)
return 1;
return 0;
}
m = (n - n_jacobi(5L, n)) / 2; /* cannot overflow
as (5/n) = 0 for n = 2^64-1 */
if (FLINT_BIT_COUNT(n) <= FLINT_D_BITS)
{
double npre = n_precompute_inverse(n);
V = fchain_precomp(m, n, npre);
return (n_mulmod_precomp(n - 3UL, V.x, n, npre) ==
n_mulmod_precomp(2UL, V.y, n, npre));
}
else
{
mp_limb_t ninv = n_preinvert_limb(n);
V = fchain2_preinv(m, n, ninv);
return (n_mulmod2_preinv(n - 3UL, V.x, n, ninv) ==
n_mulmod2_preinv(2UL, V.y, n, ninv));
}
}
n_pair_t
fchain_precomp(mp_limb_t m, mp_limb_t n, double npre)
{
n_pair_t current = {0, 0}, old;
int length;
mp_limb_t power, xy;
old.x = 2UL;
old.y = n - 3UL;
length = FLINT_BIT_COUNT(m);
power = (1UL << (length - 1));
for (; length > 0; length--)
{
xy = n_mulmod_precomp(old.x, old.y, n, npre);
xy = n_addmod(xy, 3UL, n);
if (m & power)
{
current.y =
n_submod(n_mulmod_precomp(old.y, old.y, n, npre), 2UL, n);
current.x = xy;
}
else
{
current.x =
n_submod(n_mulmod_precomp(old.x, old.x, n, npre), 2UL, n);
current.y = xy;
}
power >>= 1;
old = current;
}
return current;
}
int main(void)
{
int i, result;
FLINT_TEST_INIT(state);
flint_printf("mulmod_precomp....");
fflush(stdout);
for (i = 0; i < 100000 * flint_test_multiplier(); i++)
{
mp_limb_t a, b, d, r1, r2, p1, p2, dinv;
double dpre;
mp_limb_t bits = n_randint(state, FLINT_D_BITS) + 1;
d = n_randtest_bits(state, bits);
a = n_randtest(state) % d;
b = n_randtest(state) % d;
dpre = n_precompute_inverse(d);
r1 = n_mulmod_precomp(a, b, d, dpre);
umul_ppmm(p1, p2, a, b);
dinv = n_preinvert_limb(d);
r2 = n_ll_mod_preinv(p1, p2, d, dinv);
result = (r1 == r2);
if (!result)
{
flint_printf("FAIL:\n");
flint_printf("a = %wu, b = %wu, d = %wu, dinv = %f\n", a, b, d, dpre);
flint_printf("r1 = %wu, r2 = %wu\n", r1, r2);
abort();
}
}
FLINT_TEST_CLEANUP(state);
flint_printf("PASS\n");
return 0;
}
