Ejemplo n.º 1
0
void fb_rdc_basic(fb_t c, dv_t a) {
	int j, k;
	dig_t *tmpa;
	dv_t r;

	dv_null(r);

	TRY {
		dv_new(r);

		tmpa = a + FB_DIGS;

		/* First reduce the high part. */
		for (int i = fb_bits(tmpa) - 1; i >= 0; i--) {
			if (fb_get_bit(tmpa, i)) {
				SPLIT(k, j, i - FB_BITS, FB_DIG_LOG);
				if (k <= 0) {
					fb_addd_low(tmpa + j, tmpa + j, fb_poly_get(), FB_DIGS);
				} else {
					r[FB_DIGS] = fb_lshb_low(r, fb_poly_get(), k);
					fb_addd_low(tmpa + j, tmpa + j, r, FB_DIGS + 1);
				}
			}
		}
		for (int i = fb_bits(a) - 1; i >= FB_BITS; i--) {
			if (fb_get_bit(a, i)) {
				SPLIT(k, j, i - FB_BITS, FB_DIG_LOG);
				if (k == 0) {
					fb_addd_low(a + j, a + j, fb_poly_get(), FB_DIGS);
				} else {
					r[FB_DIGS] = fb_lshb_low(r, fb_poly_get(), k);
					fb_addd_low(a + j, a + j, r, FB_DIGS + 1);
				}
			}
		}

		fb_copy(c, a);
	}
	CATCH_ANY {
		THROW(ERR_CAUGHT);
	}
	FINALLY {
		fb_free(r);
	}
}
Ejemplo n.º 2
0
void fb_invn_low(dig_t *c, const dig_t *a) {
	int j, d, lu, lv, lt, l1, l2, bu, bv;
	align dig_t _u[2 * FB_DIGS], _v[2 * FB_DIGS];
	align dig_t _g1[2 * FB_DIGS], _g2[2 * FB_DIGS];
	dig_t *t = NULL, *u = NULL, *v = NULL, *g1 = NULL, *g2 = NULL, carry;

	dv_zero(_g1, FB_DIGS + 1);
	dv_zero(_g2, FB_DIGS + 1);

	u = _u;
	v = _v;
	g1 = _g1;
	g2 = _g2;

	/* u = a, v = f, g1 = 1, g2 = 0. */
	dv_copy(u, a, FB_DIGS);
	dv_copy(v, fb_poly_get(), FB_DIGS);
	g1[0] = 1;

	lu = lv = FB_DIGS;
	l1 = l2 = 1;

	bu = fb_bits(u);
	bv = FB_BITS + 1;
	j = bu - bv;

	/* While (u != 1). */
	while (1) {
		/* If j < 0 then swap(u, v), swap(g1, g2), j = -j. */
		if (j < 0) {
			t = u;
			u = v;
			v = t;

			lt = lu;
			lu = lv;
			lv = lt;

			t = g1;
			g1 = g2;
			g2 = t;

			lt = l1;
			l1 = l2;
			l2 = lt;

			j = -j;
		}

		SPLIT(j, d, j, FB_DIG_LOG);

		/* u = u + v * z^j. */
		if (j > 0) {
			carry = fb_lsha_low(u + d, v, j, lv);
			u[d + lv] ^= carry;
		} else {
			fb_addd_low(u + d, u + d, v, lv);
		}

		/* g1 = g1 + g2 * z^j. */
		if (j > 0) {
			carry = fb_lsha_low(g1 + d, g2, j, l2);
			l1 = (l2 + d >= l1 ? l2 + d : l1);
			if (carry) {
				g1[d + l2] ^= carry;
				l1 = (l2 + d >= l1 ? l1 + 1 : l1);
			}
		} else {
			fb_addd_low(g1 + d, g1 + d, g2, l2);
			l1 = (l2 + d > l1 ? l2 + d : l1);
		}

		while (u[lu - 1] == 0)
			lu--;
		while (v[lv - 1] == 0)
			lv--;

		if (lu == 1 && u[0] == 1)
			break;

		/* j = deg(u) - deg(v). */
		lt = util_bits_dig(u[lu - 1]) - util_bits_dig(v[lv - 1]);
		j = ((lu - lv) << FB_DIG_LOG) + lt;
	}
	/* Return g1. */
	fb_copy(c, g1);
}