} else {
            System.arraycopy( b, off, pipe_buf, nxt_idx, len );
        }
        nxt_idx = ( nxt_idx + len ) % pipe_buf.length;
        used += len;
        return len;
    }
    public int dce_read( byte[] b, int off, int len ) throws IOException {
        return super.read(b, off, len);
    }