ys, t);
        t.subTo(y, y); // "negative" y so we can replace sub with am later
        while (y.t < ys) y[y.t++] = 0;
        while (--j >= 0) {
            // Estimate quotient digit
            var qd = (r[--i] == y0) ? self.DM : Math.floor(r[i] * d1 + (r[i - 1] + e) * d2);
            if ((r[i] += y.am(0, qd, r, j, 0, ys)) < qd) {  // Try it out
                y.dlShiftTo(j, t);
                r.subTo(t, r);
                while (r[i] < --qd) r.subTo(t, r);
            }
        }
        if (q !=