memcpy(ret, lines, count * sizeof(ret[0]));
memcpy(ret + count, prev, prev_total * sizeof(ret[0]));
memcpy(ret + count + prev_total, lines + count,
memcpy(ret, lines, count * sizeof(ret[0]));
memcpy(ret + count, prev, prev_total * sizeof(ret[0]));
memcpy(ret + count + prev_total, lines + count,