(&mut dst[..size]).copy_from_slice(&src[..size]);
let mut order_idx = 0;
synth_recursive(dst, tmpbuf, size, order, &mut order_idx, false);
(&mut dst[..size]).copy_from_slice(&src[..size]);
let mut order_idx = 0;
synth_recursive(dst, tmpbuf, size, order, &mut order_idx, false);