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[/] [or1k/] [trunk/] [insight/] [gdb/] [event-loop.h] - Blame information for rev 1765

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

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