+extern int serial_readchar (struct serial *scb, int timeout);
+
+/* Write LEN chars from STRING to the port SCB. Returns 0 for
+ success, non-zero for failure. */
+
+extern int serial_write (struct serial *scb, const char *str, int len);
+
+/* Write a printf style string onto the serial port. */
+
+extern void serial_printf (struct serial *desc, const char *,...) ATTR_FORMAT (printf, 2, 3);
+
+/* Allow pending output to drain. */
+
+extern int serial_drain_output (struct serial *);
+
+/* Flush (discard) pending output. Might also flush input (if this
+ system can't flush only output). */
+
+extern int serial_flush_output (struct serial *);
+
+/* Flush pending input. Might also flush output (if this system can't
+ flush only input). */
+
+extern int serial_flush_input (struct serial *);
+
+/* Send a break between 0.25 and 0.5 seconds long. */
+
+extern int serial_send_break (struct serial *scb);
+
+/* Turn the port into raw mode. */
+
+extern void serial_raw (struct serial *scb);
+
+/* Return a pointer to a newly malloc'd ttystate containing the state
+ of the tty. */
+
+extern serial_ttystate serial_get_tty_state (struct serial *scb);
+
+/* Set the state of the tty to TTYSTATE. The change is immediate.
+ When changing to or from raw mode, input might be discarded.
+ Returns 0 for success, negative value for error (in which case
+ errno contains the error). */
+
+extern int serial_set_tty_state (struct serial *scb, serial_ttystate ttystate);
+
+/* printf_filtered a user-comprehensible description of ttystate on
+ the specified STREAM. FIXME: At present this sends output to the
+ default stream - GDB_STDOUT. */
+
+extern void serial_print_tty_state (struct serial *scb, serial_ttystate ttystate, struct ui_file *);
+
+/* Set the tty state to NEW_TTYSTATE, where OLD_TTYSTATE is the
+ current state (generally obtained from a recent call to
+ serial_get_tty_state()), but be careful not to discard any input.
+ This means that we never switch in or out of raw mode, even if
+ NEW_TTYSTATE specifies a switch. */
+
+extern int serial_noflush_set_tty_state (struct serial *scb, serial_ttystate new_ttystate, serial_ttystate old_ttystate);
+
+/* Set the baudrate to the decimal value supplied. Returns 0 for
+ success, -1 for failure. */
+
+extern int serial_setbaudrate (struct serial *scb, int rate);
+
+/* Set the number of stop bits to the value specified. Returns 0 for
+ success, -1 for failure. */
+
+#define SERIAL_1_STOPBITS 1
+#define SERIAL_1_AND_A_HALF_STOPBITS 2 /* 1.5 bits, snicker... */
+#define SERIAL_2_STOPBITS 3
+
+extern int serial_setstopbits (struct serial *scb, int num);