+/* Increment reference count of SCB. */
+
+extern void serial_ref (struct serial *scb);
+
+/* Decrement reference count of SCB. */
+
+extern void serial_unref (struct serial *scb);
+
+/* Create a pipe, and put the read end in FILDES[0], and the write end
+ in FILDES[1]. Returns 0 for success, negative value for error (in
+ which case errno contains the error). */
+
+extern int gdb_pipe (int fildes[2]);
+
+/* Create a pipe with each end wrapped in a `struct serial' interface.
+ Put the read end in scbs[0], and the write end in scbs[1]. Returns
+ 0 for success, negative value for error (in which case errno
+ contains the error). */
+
+extern int serial_pipe (struct serial *scbs[2]);
+