/* Add a character or operation byte to the echo buffer.  */
rt_inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
/* Add a character or operation byte to the echo buffer.  */
rt_inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
{
    *echo_buf_addr(ldata, ldata->echo_head++) = c;
}