C++ (Cpp) n_powmod2_ui_preinv Examples

Example #1

File: is_strong_probabprime2_preinv.c Project: krisk0/razin

static __inline__ int
n_is_strong_probabprime2_preinv_speedup(mp_limb_t n, mp_limb_t ninv, mp_limb_t a,
                                mp_limb_t d)
/*
this subroutine does Miller-Rabin test and returns positive iff test passes

hacked by Денис Крыськов to count n-1 once
*/
 {
    mp_limb_t t = d;
    mp_limb_t y;

    y = n_powmod2_ui_preinv(a, t, n, ninv);

    if (y == UWORD(1))
        return 1;
    t <<= 1;

    d = n-1;        // Денис Крыськов was here
    while ((t != d) && (y != d))  // and here
     {
        y = n_mulmod2_preinv(y, y, n, ninv);
        t <<= 1;
     }
    return y == d;            // and here
 }

Example #2

File: powmod2_preinv.c Project: clear731/lattice

mp_limb_t
n_powmod2_preinv(mp_limb_t a, mp_limb_signed_t exp, mp_limb_t n, mp_limb_t ninv)
{
    if (exp < WORD(0))
    {
        a = n_invmod(a, n);
        exp = -exp;
    }

    return n_powmod2_ui_preinv(a, exp, n, ninv);
}

Example #3

File: pow.c Project: clear731/lattice

void
nmod_poly_pow(nmod_poly_t res, const nmod_poly_t poly, ulong e)
{
    const slong len = poly->length;
    slong rlen;

    if ((len < 2) | (e < UWORD(3)))
    {
        if (len == 0)
            nmod_poly_zero(res);
        else if (len == 1)
        {
            nmod_poly_fit_length(res, 1);
            res->coeffs[0] = n_powmod2_ui_preinv(poly->coeffs[0], e,
                poly->mod.n, poly->mod.ninv);
            res->length = 1;
            _nmod_poly_normalise(res);
        }
        else if (e == UWORD(0))
        {
            nmod_poly_set_coeff_ui(res, 0, UWORD(1));
            res->length = 1;
            _nmod_poly_normalise(res);
        }
        else if (e == UWORD(1))
            nmod_poly_set(res, poly);
        else  /* e == UWORD(2) */
            nmod_poly_mul(res, poly, poly);

        return;
    }

    rlen = (slong) e * (len - 1) + 1;

    if (res != poly)
    {
        nmod_poly_fit_length(res, rlen);
        _nmod_poly_pow(res->coeffs, poly->coeffs, len, e, poly->mod);
    }
    else
    {
        nmod_poly_t t;
        nmod_poly_init2(t, poly->mod.n, rlen);
        _nmod_poly_pow(t->coeffs, poly->coeffs, len, e, poly->mod);
        nmod_poly_swap(res, t);
        nmod_poly_clear(t);
    }

    res->length = rlen;
    _nmod_poly_normalise(res);
}

Example #4

File: sqrtmod.c Project: clear731/lattice

mp_limb_t n_sqrtmod(mp_limb_t a, mp_limb_t p) 
{
    slong i, r, m;
    mp_limb_t p1, k, b, g, bpow, gpow, res;
    mp_limb_t pinv;

    if (a <= 1)
    {
        return a;
    }

    pinv = n_preinvert_limb(p);

    if (n_jacobi_unsigned(a, p) == -1)
        return 0;

    if ((p & UWORD(3)) == 3)
    {
        return n_powmod2_ui_preinv(a, (p + 1) / 4, p, pinv);
    }

    r = 0;
    p1 = p - 1;

    do {
        p1 >>= UWORD(1); 
        r++;
    } while ((p1 & UWORD(1)) == 0);

    b = n_powmod2_ui_preinv(a, p1, p, pinv);

    for (k = 2; ; k++)
    {
        if (n_jacobi_unsigned(k, p) == -1) break;
    }

    g = n_powmod2_ui_preinv(k, p1, p, pinv);
    res = n_powmod2_ui_preinv(a, (p1 + 1) / 2, p, pinv);

    while (b != 1)
    {
        bpow = b;
        m = 0;
        do
        {
            bpow = n_mulmod2_preinv(bpow, bpow, p, pinv);
            m++;
        } while (m < r && bpow != 1);
        gpow = g;
        for (i = 1; i < r - m; i++)
        {
            gpow = n_mulmod2_preinv(gpow, gpow, p, pinv);
        }
        res = n_mulmod2_preinv(res, gpow, p, pinv);
        g = n_mulmod2_preinv(gpow, gpow, p, pinv);
        b = n_mulmod2_preinv(b, g, p, pinv);
        r = m;
    }

    return res;
}