pio_read
retval = pio_read(board, ines_priv, buffer, length, bytes_read);
retval = pio_read(board, priv, buffer, length, end, bytes_read);
retval = pio_read(board, priv, buffer, length - 1, end, &num_bytes);
retval = pio_read(board, priv, buffer, length, end, &num_bytes);
ret = pio_read(ctrl);