 > 0) r[--i] = 0;
        var j;
        for (j = r.t - this.t; i < j; ++i) r[i + this.t] = this.am(0, a[i], r, i, 0, this.t);
        for (j = Math.min(a.t, n); i < j; ++i) this.am(0, a[i], r, i, 0, n - i);
        r.clamp();
    }

// (protected) r = "this * a" without lower n words, n > 0
// "this" should be the larger one if appropriate.
    function bnpMultiplyUpperTo(a, n, r) {
        --n;
        var i = r.t = this.t + a.t - n;
        r.s = 0; // assumes a,this >= 0
        while (--i >= 0) r[i] = 