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diff --git a/contrib/gdb/gdb/event-loop.h b/contrib/gdb/gdb/event-loop.h
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+/* Definitions used by the GDB event loop.
+   Copyright 1999, 2000 Free Software Foundation, Inc.
+   Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+/* An event loop listens for events from multiple event sources. When
+   an event arrives, it is queued and processed by calling the
+   appropriate event handler. The event loop then continues to listen
+   for more events. An event loop completes when there are no event
+   sources to listen on.  External event sources can be plugged into
+   the loop.
+
+   There are 3 main components: 
+   - a list of file descriptors to be monitored, GDB_NOTIFIER.  
+   - a list of events that have occurred, EVENT_QUEUE.  
+   - a list of signal handling functions, SIGHANDLER_LIST.
+
+   GDB_NOTIFIER keeps track of the event sources. Event sources for
+   gdb are currently the UI and the target.  Gdb communicates with the
+   command line user interface via the readline library and usually
+   communicates with remote targets via a serial port. Serial ports
+   are represented in GDB as file descriptors and select/poll calls.
+   For native targets instead, the communication consists of calls to
+   ptrace and waits (via signals) or calls to poll/select (via file
+   descriptors). In the current gdb, the code handling events related
+   to the target resides in the wait_for_inferior function and in
+   various target specific files (*-tdep.c).
+
+   EVENT_QUEUE keeps track of the events that have happened during the
+   last iteration of the event loop, and need to be processed.  An
+   event is represented by a procedure to be invoked in order to
+   process the event.  The queue is scanned head to tail.  If the
+   event of interest is a change of state in a file descriptor, then a
+   call to poll or select will be made to detect it.
+
+   If the events generate signals, they are also queued by special
+   functions that are invoked through traditional signal handlers.
+   The actions to be taken is response to such events will be executed
+   when the SIGHANDLER_LIST is scanned, the next time through the
+   infinite loop.  
+
+   Corollary tasks are the creation and deletion of event sources. */
+
+typedef void *gdb_client_data;
+struct async_signal_handler;
+typedef void (handler_func) (int, gdb_client_data);
+typedef void (sig_handler_func) (gdb_client_data);
+typedef void (timer_handler_func) (gdb_client_data);
+
+/* Where to add an event onto the event queue, by queue_event. */
+typedef enum
+  {
+    /* Add at tail of queue. It will be processed in first in first
+       out order. */
+    TAIL,
+    /* Add at head of queue. It will be processed in last in first out
+       order. */
+    HEAD
+  }
+queue_position;
+
+/* Tell create_file_handler what events we are interested in. 
+   This is used by the select version of the event loop. */
+
+#define GDB_READABLE	(1<<1)
+#define GDB_WRITABLE	(1<<2)
+#define GDB_EXCEPTION	(1<<3)
+
+/* Exported functions from event-loop.c */
+
+extern void start_event_loop (void);
+extern void delete_file_handler (int fd);
+extern void add_file_handler (int fd, handler_func * proc, gdb_client_data client_data);
+extern void mark_async_signal_handler (struct async_signal_handler *async_handler_ptr);
+extern struct async_signal_handler *
+  create_async_signal_handler (sig_handler_func * proc, gdb_client_data client_data);
+extern void delete_async_signal_handler (struct async_signal_handler **async_handler_ptr);
+extern int create_timer (int milliseconds, timer_handler_func * proc, gdb_client_data client_data);
+extern void delete_timer (int id);