n -= int(cur - r.l)
		cur = r.l
	}
	for i := range b[0:n] {
		if r.cur+int64(i) >= r.l-1<<16 {
			b[i] = 1
		} else {
			b[i] = 0
		}
	}
	r.cur = cur
	return
}

func TestVeryLongSparseChunk(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping sparse chunk during short test")
	}
	w, err := NewWriter(io.Discard, 1)
	if err != nil {
		t.Errorf("NewWriter: %v", err)
		return
	}