(protected) r = this << n
function bnpLShiftTo(n,r) {
  var this_array = this.array;
  var r_array = r.array;
  var bs = n%BI_DB;
  var cbs = BI_DB-bs;
  var bm = (1<<cbs)-1;
  var ds = Math.floor(n/BI_DB), c = (this.s<<bs)&BI_DM, i;
  for(i = this.t-1; i >= 0; --i) {
    r_array[i+ds+1] = (this_array[i]>>cbs)|c;
    c = (this_array[i]&bm)<<bs;
  }
  for(i = ds-1; i >= 0; --i) r_array[i] = 0;
  r_array[ds] = c;
  r.t = this.t+ds+1;
  r.s = this.s;
  r.clamp();
}