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/* Keyboard and mouse input; editor command loop.
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   Copyright (C) 1985,86,87,88,89,93,94 Free Software Foundation, Inc.
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This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.

GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* Allow config.h to undefine symbols found here.  */
#include <signal.h>

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#include <config.h>
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#include <stdio.h>
#undef NULL
#include "termchar.h"
#include "termopts.h"
#include "lisp.h"
#include "termhooks.h"
#include "macros.h"
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#include "frame.h"
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#include "window.h"
#include "commands.h"
#include "buffer.h"
#include "disptab.h"
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#include "dispextern.h"
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#include "keyboard.h"
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#include "intervals.h"
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#include "blockinput.h"
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#include <setjmp.h>
#include <errno.h>

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#ifdef MSDOS
#include "msdos.h"
#include <time.h>
#else /* not MSDOS */
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#ifndef VMS
#include <sys/ioctl.h>
#endif
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#endif /* not MSDOS */
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#include "syssignal.h"
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#include "systty.h"
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#include "systime.h"
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extern int errno;

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/* Variables for blockinput.h: */

/* Non-zero if interrupt input is blocked right now.  */
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int interrupt_input_blocked;
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/* Nonzero means an input interrupt has arrived
   during the current critical section.  */
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int interrupt_input_pending;
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#ifdef HAVE_X_WINDOWS
extern Lisp_Object Vmouse_grabbed;

/* Make all keyboard buffers much bigger when using X windows.  */
#define KBD_BUFFER_SIZE 4096
#else	/* No X-windows, character input */
#define KBD_BUFFER_SIZE 256
#endif	/* No X-windows */

/* Following definition copied from eval.c */

struct backtrace
  {
    struct backtrace *next;
    Lisp_Object *function;
    Lisp_Object *args;	/* Points to vector of args. */
    int nargs;		/* length of vector.  If nargs is UNEVALLED,
			   args points to slot holding list of
			   unevalled args */
    char evalargs;
  };

/* Non-nil disable property on a command means
   do not execute it; call disabled-command-hook's value instead.  */
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Lisp_Object Qdisabled, Qdisabled_command_hook;
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#define NUM_RECENT_KEYS (100)
int recent_keys_index;	/* Index for storing next element into recent_keys */
int total_keys;		/* Total number of elements stored into recent_keys */
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Lisp_Object recent_keys; /* A vector, holding the last 100 keystrokes */
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/* Vector holding the key sequence that invoked the current command.
   It is reused for each command, and it may be longer than the current
   sequence; this_command_key_count indicates how many elements
   actually mean something.
   It's easier to staticpro a single Lisp_Object than an array.  */
Lisp_Object this_command_keys;
int this_command_key_count;
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extern int minbuf_level;

extern struct backtrace *backtrace_list;

/* Nonzero means do menu prompting.  */
static int menu_prompting;

/* Character to see next line of menu prompt.  */
static Lisp_Object menu_prompt_more_char;

/* For longjmp to where kbd input is being done.  */
static jmp_buf getcjmp;

/* True while doing kbd input.  */
int waiting_for_input;

/* True while displaying for echoing.   Delays C-g throwing.  */
static int echoing;

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/* Nonzero means C-g should cause immediate error-signal.  */
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int immediate_quit;

/* Character to recognize as the help char.  */
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Lisp_Object Vhelp_char;
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/* Form to execute when help char is typed.  */
Lisp_Object Vhelp_form;

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/* Command to run when the help character follows a prefix key.  */
Lisp_Object Vprefix_help_command;

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/* List of items that should move to the end of the menu bar.  */
Lisp_Object Vmenu_bar_final_items;
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/* Character that causes a quit.  Normally C-g.

   If we are running on an ordinary terminal, this must be an ordinary
   ASCII char, since we want to make it our interrupt character.

   If we are not running on an ordinary terminal, it still needs to be
   an ordinary ASCII char.  This character needs to be recognized in
   the input interrupt handler.  At this point, the keystroke is
   represented as a struct input_event, while the desired quit
   character is specified as a lispy event.  The mapping from struct
   input_events to lispy events cannot run in an interrupt handler,
   and the reverse mapping is difficult for anything but ASCII
   keystrokes.

   FOR THESE ELABORATE AND UNSATISFYING REASONS, quit_char must be an
   ASCII character.  */
int quit_char;

extern Lisp_Object current_global_map;
extern int minibuf_level;

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/* If non-nil, this is a map that overrides all other local maps.  */
Lisp_Object Voverriding_local_map;

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/* Current depth in recursive edits.  */
int command_loop_level;

/* Total number of times command_loop has read a key sequence.  */
int num_input_keys;

/* Last input character read as a command.  */
Lisp_Object last_command_char;

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/* Last input character read as a command, not counting menus
   reached by the mouse.  */
Lisp_Object last_nonmenu_event;

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/* Last input character read for any purpose.  */
Lisp_Object last_input_char;

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/* If not Qnil, a list of objects to be read as subsequent command input.  */
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Lisp_Object Vunread_command_events;
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/* If not -1, an event to be read as subsequent command input.  */
int unread_command_char;

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/* If not Qnil, this is a switch-frame event which we decided to put
   off until the end of a key sequence.  This should be read as the
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   next command input, after any unread_command_events.
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   read_key_sequence uses this to delay switch-frame events until the
   end of the key sequence; Fread_char uses it to put off switch-frame
   events until a non-ASCII event is acceptable as input.  */
Lisp_Object unread_switch_frame;
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/* A mask of extra modifier bits to put into every keyboard char.  */
int extra_keyboard_modifiers;

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/* Char to use as prefix when a meta character is typed in.
   This is bound on entry to minibuffer in case ESC is changed there.  */

Lisp_Object meta_prefix_char;

/* Last size recorded for a current buffer which is not a minibuffer.  */
static int last_non_minibuf_size;

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/* Number of idle seconds before an auto-save and garbage collection.  */
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static Lisp_Object Vauto_save_timeout;

/* Total number of times read_char has returned.  */
int num_input_chars;

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/* Total number of times read_char has returned, outside of macros.  */
int num_nonmacro_input_chars;

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/* Auto-save automatically when this many characters have been typed
   since the last time.  */

static int auto_save_interval;

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/* Value of num_nonmacro_input_chars as of last auto save.  */
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int last_auto_save;

/* Last command executed by the editor command loop, not counting
   commands that set the prefix argument.  */

Lisp_Object last_command;

/* The command being executed by the command loop.
   Commands may set this, and the value set will be copied into last_command
   instead of the actual command.  */
Lisp_Object this_command;

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/* The value of point when the last command was executed.  */
int last_point_position;

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/* The buffer that was current when the last command was started.  */
Lisp_Object last_point_position_buffer;

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#ifdef MULTI_FRAME
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/* The frame in which the last input event occurred, or Qmacro if the
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   last event came from a macro.  We use this to determine when to
   generate switch-frame events.  This may be cleared by functions
   like Fselect_frame, to make sure that a switch-frame event is
   generated by the next character.  */
Lisp_Object internal_last_event_frame;
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#endif
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/* A user-visible version of the above, intended to allow users to
   figure out where the last event came from, if the event doesn't
   carry that information itself (i.e. if it was a character).  */
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Lisp_Object Vlast_event_frame;
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/* The timestamp of the last input event we received from the X server.
   X Windows wants this for selection ownership.  */
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unsigned long last_event_timestamp;

Lisp_Object Qself_insert_command;
Lisp_Object Qforward_char;
Lisp_Object Qbackward_char;
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Lisp_Object Qundefined;
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/* read_key_sequence stores here the command definition of the
   key sequence that it reads.  */
Lisp_Object read_key_sequence_cmd;

/* Form to evaluate (if non-nil) when Emacs is started.  */
Lisp_Object Vtop_level;

/* User-supplied string to translate input characters through.  */
Lisp_Object Vkeyboard_translate_table;

/* Keymap mapping ASCII function key sequences onto their preferred forms.  */
extern Lisp_Object Vfunction_key_map;

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/* Keymap mapping ASCII function key sequences onto their preferred forms.  */
Lisp_Object Vkey_translation_map;

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/* Non-nil means deactivate the mark at end of this command.  */
Lisp_Object Vdeactivate_mark;

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/* Menu bar specified in Lucid Emacs fashion.  */

Lisp_Object Vlucid_menu_bar_dirty_flag;
Lisp_Object Qrecompute_lucid_menubar, Qactivate_menubar_hook;

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/* Hooks to run before and after each command.  */
Lisp_Object Qpre_command_hook, Qpost_command_hook;
Lisp_Object Vpre_command_hook, Vpost_command_hook;
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Lisp_Object Qcommand_hook_internal, Vcommand_hook_internal;
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/* File in which we write all commands we read.  */
FILE *dribble;

/* Nonzero if input is available.  */
int input_pending;

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/* 1 if should obey 0200 bit in input chars as "Meta", 2 if should
   keep 0200 bit in input chars.  0 to ignore the 0200 bit.  */

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int meta_key;

extern char *pending_malloc_warning;

/* Circular buffer for pre-read keyboard input.  */
static struct input_event kbd_buffer[KBD_BUFFER_SIZE];

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/* Vector to GCPRO the frames and windows mentioned in kbd_buffer.
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   The interrupt-level event handlers will never enqueue an event on a
   frame which is not in Vframe_list, and once an event is dequeued,
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   internal_last_event_frame or the event itself points to the frame.
   So that's all fine.
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   But while the event is sitting in the queue, it's completely
   unprotected.  Suppose the user types one command which will run for
   a while and then delete a frame, and then types another event at
   the frame that will be deleted, before the command gets around to
   it.  Suppose there are no references to this frame elsewhere in
   Emacs, and a GC occurs before the second event is dequeued.  Now we
   have an event referring to a freed frame, which will crash Emacs
   when it is dequeued.

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   Similar things happen when an event on a scroll bar is enqueued; the
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   window may be deleted while the event is in the queue.
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   So, we use this vector to protect the frame_or_window field in the
   event queue.  That way, they'll be dequeued as dead frames or
   windows, but still valid lisp objects.

   If kbd_buffer[i].kind != no_event, then
     (XVECTOR (kbd_buffer_frame_or_window)->contents[i]
      == kbd_buffer[i].frame_or_window.  */
static Lisp_Object kbd_buffer_frame_or_window;
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/* Pointer to next available character in kbd_buffer.
   If kbd_fetch_ptr == kbd_store_ptr, the buffer is empty.
   This may be kbd_buffer + KBD_BUFFER_SIZE, meaning that the the
   next available char is in kbd_buffer[0].  */
static struct input_event *kbd_fetch_ptr;

/* Pointer to next place to store character in kbd_buffer.  This
   may be kbd_buffer + KBD_BUFFER_SIZE, meaning that the next
   character should go in kbd_buffer[0].  */
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#ifdef __STDC__
volatile
#endif
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static struct input_event *kbd_store_ptr;

/* The above pair of variables forms a "queue empty" flag.  When we
   enqueue a non-hook event, we increment kbd_write_count.  When we
   dequeue a non-hook event, we increment kbd_read_count.  We say that
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   there is input available iff the two counters are not equal.
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   Why not just have a flag set and cleared by the enqueuing and
   dequeuing functions?  Such a flag could be screwed up by interrupts
   at inopportune times.  */

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/* If this flag is non-zero, we check mouse_moved to see when the
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   mouse moves, and motion events will appear in the input stream.  If
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   it is zero, mouse motion is ignored.  */
static int do_mouse_tracking;
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/* The window system handling code should set this if the mouse has
   moved since the last call to the mouse_position_hook.  Calling that
   hook should clear this.  Code assumes that if this is set, it can
   call mouse_position_hook to get the promised position, so don't set
   it unless you're prepared to substantiate the claim!  */
int mouse_moved;

/* True iff there is an event in kbd_buffer, or if mouse tracking is
   enabled and there is a new mouse position in the mouse movement
   buffer.  Note that if this is false, that doesn't mean that there
   is readable input; all the events in the queue might be button-up
   events, and do_mouse_tracking might be off.  */
#define EVENT_QUEUES_EMPTY \
  ((kbd_fetch_ptr == kbd_store_ptr) && (!do_mouse_tracking || !mouse_moved))


/* Symbols to head events.  */
Lisp_Object Qmouse_movement;
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Lisp_Object Qscroll_bar_movement;
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Lisp_Object Qswitch_frame;

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/* Symbols to denote kinds of events.  */
Lisp_Object Qfunction_key;
Lisp_Object Qmouse_click;
/* Lisp_Object Qmouse_movement; - also an event header */

/* Properties of event headers.  */
Lisp_Object Qevent_kind;
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Lisp_Object Qevent_symbol_elements;
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Lisp_Object Qmenu_enable;

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/* An event header symbol HEAD may have a property named
   Qevent_symbol_element_mask, which is of the form (BASE MODIFIERS);
   BASE is the base, unmodified version of HEAD, and MODIFIERS is the
   mask of modifiers applied to it.  If present, this is used to help
   speed up parse_modifiers.  */
Lisp_Object Qevent_symbol_element_mask;

/* An unmodified event header BASE may have a property named
   Qmodifier_cache, which is an alist mapping modifier masks onto
   modified versions of BASE.  If present, this helps speed up
   apply_modifiers.  */
Lisp_Object Qmodifier_cache;

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/* Symbols to use for parts of windows.  */
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Lisp_Object Qmode_line;
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Lisp_Object Qvertical_line;
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Lisp_Object Qvertical_scroll_bar;
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Lisp_Object Qmenu_bar;

extern Lisp_Object Qmenu_enable;
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Lisp_Object recursive_edit_unwind (), command_loop ();
Lisp_Object Fthis_command_keys ();
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Lisp_Object Qextended_command_history;
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/* Address (if not 0) of EMACS_TIME to zero out if a SIGIO interrupt
   happens.  */
EMACS_TIME *input_available_clear_time;
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/* Nonzero means use SIGIO interrupts; zero means use CBREAK mode.
   Default is 1 if INTERRUPT_INPUT is defined.  */
int interrupt_input;

/* Nonzero while interrupts are temporarily deferred during redisplay.  */
int interrupts_deferred;

/* nonzero means use ^S/^Q for flow control.  */
int flow_control;

/* Allow m- file to inhibit use of FIONREAD.  */
#ifdef BROKEN_FIONREAD
#undef FIONREAD
#endif

/* We are unable to use interrupts if FIONREAD is not available,
   so flush SIGIO so we won't try.  */
#ifndef FIONREAD
#ifdef SIGIO
#undef SIGIO
#endif
#endif

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/* If we support X Windows, turn on the code to poll periodically
   to detect C-g.  It isn't actually used when doing interrupt input.  */
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#ifdef HAVE_X_WINDOWS
#define POLL_FOR_INPUT
#endif

/* Global variable declarations.  */

/* Function for init_keyboard to call with no args (if nonzero).  */
void (*keyboard_init_hook) ();

static int read_avail_input ();
static void get_input_pending ();
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static int readable_events ();
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static Lisp_Object read_char_x_menu_prompt ();
static Lisp_Object read_char_minibuf_menu_prompt ();
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static Lisp_Object make_lispy_event ();
static Lisp_Object make_lispy_movement ();
static Lisp_Object modify_event_symbol ();
static Lisp_Object make_lispy_switch_frame ();
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/* > 0 if we are to echo keystrokes.  */
static int echo_keystrokes;

/* Nonzero means echo each character as typed.  */
static int immediate_echo;

/* The text we're echoing in the modeline - partial key sequences,
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   usually.  '\0'-terminated.  This really shouldn't have a fixed size.  */
static char echobuf[300];
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/* Where to append more text to echobuf if we want to.  */
static char *echoptr;

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/* Nonzero means don't try to suspend even if the operating system seems
   to support it.  */
static int cannot_suspend;

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#define	min(a,b)	((a)<(b)?(a):(b))
#define	max(a,b)	((a)>(b)?(a):(b))

/* Install the string STR as the beginning of the string of echoing,
   so that it serves as a prompt for the next character.
   Also start echoing.  */

echo_prompt (str)
     char *str;
{
  int len = strlen (str);
  if (len > sizeof echobuf - 4)
    len = sizeof echobuf - 4;
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  bcopy (str, echobuf, len);
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  echoptr = echobuf + len;
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  *echoptr = '\0';
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  echo ();
}

/* Add C to the echo string, if echoing is going on.  
   C can be a character, which is printed prettily ("M-C-x" and all that
   jazz), or a symbol, whose name is printed.  */

echo_char (c)
     Lisp_Object c;
{
  extern char *push_key_description ();

  if (immediate_echo)
    {
      char *ptr = echoptr;
      
      if (ptr != echobuf)
	*ptr++ = ' ';

      /* If someone has passed us a composite event, use its head symbol.  */
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      c = EVENT_HEAD (c);
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      if (XTYPE (c) == Lisp_Int)
	{
	  if (ptr - echobuf > sizeof echobuf - 6)
	    return;

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	  ptr = push_key_description (XINT (c), ptr);
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	}
      else if (XTYPE (c) == Lisp_Symbol)
	{
	  struct Lisp_String *name = XSYMBOL (c)->name;
	  if (((ptr - echobuf) + name->size + 4) > sizeof echobuf)
	    return;
	  bcopy (name->data, ptr, name->size);
	  ptr += name->size;
	}

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      if (echoptr == echobuf && EQ (c, Vhelp_char))
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	{
	  strcpy (ptr, " (Type ? for further options)");
	  ptr += strlen (ptr);
	}

      *ptr = 0;
      echoptr = ptr;

      echo ();
    }
}

/* Temporarily add a dash to the end of the echo string if it's not
   empty, so that it serves as a mini-prompt for the very next character.  */

echo_dash ()
{
  if (!immediate_echo && echoptr == echobuf)
    return;
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  /* Do nothing if not echoing at all.  */
  if (echoptr == 0)
    return;
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  /* Put a dash at the end of the buffer temporarily,
     but make it go away when the next character is added.  */
  echoptr[0] = '-';
  echoptr[1] = 0;

  echo ();
}

/* Display the current echo string, and begin echoing if not already
   doing so.  */

echo ()
{
  if (!immediate_echo)
    {
      int i;
      immediate_echo = 1;

      for (i = 0; i < this_command_key_count; i++)
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	echo_char (XVECTOR (this_command_keys)->contents[i]);
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      echo_dash ();
    }

  echoing = 1;
  message1 (echobuf);
  echoing = 0;

  if (waiting_for_input && !NILP (Vquit_flag))
    quit_throw_to_read_char ();
}

/* Turn off echoing, for the start of a new command.  */

cancel_echoing ()
{
  immediate_echo = 0;
  echoptr = echobuf;
}

/* Return the length of the current echo string.  */

static int
echo_length ()
{
  return echoptr - echobuf;
}

/* Truncate the current echo message to its first LEN chars.
   This and echo_char get used by read_key_sequence when the user
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   switches frames while entering a key sequence.  */
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static void
echo_truncate (len)
     int len;
{
  echobuf[len] = '\0';
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  echoptr = echobuf + len;
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  truncate_echo_area (len);
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}


/* Functions for manipulating this_command_keys.  */
static void
add_command_key (key)
     Lisp_Object key;
{
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  int size = XVECTOR (this_command_keys)->size;

  if (this_command_key_count >= size)
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    {
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      Lisp_Object new_keys;
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      new_keys = Fmake_vector (make_number (size * 2), Qnil);
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      bcopy (XVECTOR (this_command_keys)->contents,
	     XVECTOR (new_keys)->contents,
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	     size * sizeof (Lisp_Object));
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      this_command_keys = new_keys;
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    }
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  XVECTOR (this_command_keys)->contents[this_command_key_count++] = key;
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}

Lisp_Object
recursive_edit_1 ()
{
  int count = specpdl_ptr - specpdl;
  Lisp_Object val;

  if (command_loop_level > 0)
    {
      specbind (Qstandard_output, Qt);
      specbind (Qstandard_input, Qt);
    }

  val = command_loop ();
  if (EQ (val, Qt))
    Fsignal (Qquit, Qnil);

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  return unbind_to (count, Qnil);
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}

/* When an auto-save happens, record the "time", and don't do again soon.  */
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record_auto_save ()
{
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  last_auto_save = num_nonmacro_input_chars;
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}
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/* Make an auto save happen as soon as possible at command level.  */

force_auto_save_soon ()
{
  last_auto_save = - auto_save_interval - 1;
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  record_asynch_buffer_change ();
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}
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DEFUN ("recursive-edit", Frecursive_edit, Srecursive_edit, 0, 0, "",
  "Invoke the editor command loop recursively.\n\
To get out of the recursive edit, a command can do `(throw 'exit nil)';\n\
that tells this function to return.\n\
Alternately, `(throw 'exit t)' makes this function signal an error.\n\
This function is called by the editor initialization to begin editing.")
  ()
{
  int count = specpdl_ptr - specpdl;
  Lisp_Object val;

  command_loop_level++;
  update_mode_lines = 1;

  record_unwind_protect (recursive_edit_unwind,
			 (command_loop_level
			  && current_buffer != XBUFFER (XWINDOW (selected_window)->buffer))
			 ? Fcurrent_buffer ()
			 : Qnil);
  recursive_edit_1 ();
  return unbind_to (count, Qnil);
}

Lisp_Object
recursive_edit_unwind (buffer)
     Lisp_Object buffer;
{
  if (!NILP (buffer))
    Fset_buffer (buffer);

  command_loop_level--;
  update_mode_lines = 1;
  return Qnil;
}

Lisp_Object
cmd_error (data)
     Lisp_Object data;
{
  Lisp_Object errmsg, tail, errname, file_error;
  Lisp_Object stream;
  struct gcpro gcpro1;
  int i;

  Vquit_flag = Qnil;
  Vinhibit_quit = Qt;
  Vstandard_output = Qt;
  Vstandard_input = Qt;
  Vexecuting_macro = Qnil;
  echo_area_glyphs = 0;

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  /* If the window system or terminal frame hasn't been initialized
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     yet, or we're not interactive, it's best to dump this message out
     to stderr and exit.  */
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  if (! FRAME_MESSAGE_BUF (selected_frame)
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      || noninteractive)
    stream = Qexternal_debugging_output;
  else
    {
      Fdiscard_input ();
      bitch_at_user ();
      stream = Qt;
    }

  errname = Fcar (data);

  if (EQ (errname, Qerror))
    {
      data = Fcdr (data);
      if (!CONSP (data)) data = Qnil;
      errmsg = Fcar (data);
      file_error = Qnil;
    }
  else
    {
      errmsg = Fget (errname, Qerror_message);
      file_error = Fmemq (Qfile_error,
			  Fget (errname, Qerror_conditions));
    }

  /* Print an error message including the data items.
     This is done by printing it into a scratch buffer
     and then making a copy of the text in the buffer. */

  if (!CONSP (data)) data = Qnil;
  tail = Fcdr (data);
  GCPRO1 (tail);

  /* For file-error, make error message by concatenating
     all the data items.  They are all strings.  */
  if (!NILP (file_error) && !NILP (tail))
    errmsg = XCONS (tail)->car, tail = XCONS (tail)->cdr;

  if (XTYPE (errmsg) == Lisp_String)
    Fprinc (errmsg, stream);
  else
    write_string_1 ("peculiar error", -1, stream);

  for (i = 0; CONSP (tail); tail = Fcdr (tail), i++)
    {
      write_string_1 (i ? ", " : ": ", 2, stream);
      if (!NILP (file_error))
	Fprinc (Fcar (tail), stream);
      else
	Fprin1 (Fcar (tail), stream);
    }
  UNGCPRO;

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  /* If the window system or terminal frame hasn't been initialized
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     yet, or we're in -batch mode, this error should cause Emacs to exit.  */
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  if (! FRAME_MESSAGE_BUF (selected_frame)
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      || noninteractive)
    {
      Fterpri (stream);
      Fkill_emacs (make_number (-1));
    }

  Vquit_flag = Qnil;

  Vinhibit_quit = Qnil;
  return make_number (0);
}

Lisp_Object command_loop_1 ();
Lisp_Object command_loop_2 ();
Lisp_Object top_level_1 ();

/* Entry to editor-command-loop.
   This level has the catches for exiting/returning to editor command loop.
   It returns nil to exit recursive edit, t to abort it.  */

Lisp_Object
command_loop ()
{
  if (command_loop_level > 0 || minibuf_level > 0)
    {
      return internal_catch (Qexit, command_loop_2, Qnil);
    }
  else
    while (1)
      {
	internal_catch (Qtop_level, top_level_1, Qnil);
	internal_catch (Qtop_level, command_loop_2, Qnil);
	
	/* End of file in -batch run causes exit here.  */
	if (noninteractive)
	  Fkill_emacs (Qt);
      }
}

/* Here we catch errors in execution of commands within the
   editing loop, and reenter the editing loop.
   When there is an error, cmd_error runs and returns a non-nil
   value to us.  A value of nil means that cmd_loop_1 itself
   returned due to end of file (or end of kbd macro).  */

Lisp_Object
command_loop_2 ()
{
  register Lisp_Object val;

  do
    val = internal_condition_case (command_loop_1, Qerror, cmd_error);
  while (!NILP (val));

  return Qnil;
}

Lisp_Object
top_level_2 ()
{
  return Feval (Vtop_level);
}

Lisp_Object
top_level_1 ()
{
  /* On entry to the outer level, run the startup file */
  if (!NILP (Vtop_level))
    internal_condition_case (top_level_2, Qerror, cmd_error);
  else if (!NILP (Vpurify_flag))
    message ("Bare impure Emacs (standard Lisp code not loaded)");
  else
    message ("Bare Emacs (standard Lisp code not loaded)");
  return Qnil;
}

DEFUN ("top-level", Ftop_level, Stop_level, 0, 0, "",
  "Exit all recursive editing levels.")
  ()
{
  Fthrow (Qtop_level, Qnil);
}

DEFUN ("exit-recursive-edit", Fexit_recursive_edit, Sexit_recursive_edit, 0, 0, "",
  "Exit from the innermost recursive edit or minibuffer.")
  ()
{
  if (command_loop_level > 0 || minibuf_level > 0)
    Fthrow (Qexit, Qnil);

  error ("No recursive edit is in progress");
}

DEFUN ("abort-recursive-edit", Fabort_recursive_edit, Sabort_recursive_edit, 0, 0, "",
  "Abort the command that requested this recursive edit or minibuffer input.")
  ()
{
  if (command_loop_level > 0 || minibuf_level > 0)
    Fthrow (Qexit, Qt);

  error ("No recursive edit is in progress");
}

/* This is the actual command reading loop,
   sans error-handling encapsulation.  */

Lisp_Object Fcommand_execute ();
static int read_key_sequence ();

Lisp_Object
command_loop_1 ()
{
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  Lisp_Object cmd, tem;
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  int lose;
  int nonundocount;
  Lisp_Object keybuf[30];
  int i;
  int no_redisplay;
  int no_direct;
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  int prev_modiff;
  struct buffer *prev_buffer;
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  Vprefix_arg = Qnil;
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  Vdeactivate_mark = Qnil;
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  waiting_for_input = 0;
  cancel_echoing ();

  nonundocount = 0;
  no_redisplay = 0;
  this_command_key_count = 0;

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  /* Make sure this hook runs after commands that get errors and
     throw to top level.  */
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  if (!NILP (Vpost_command_hook) && !NILP (Vrun_hooks))
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    {
      /* If we get an error during the post-command-hook,
	 cause post-command-hook to be nil.  */
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      Vcommand_hook_internal = Vpost_command_hook;
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      Vpost_command_hook = Qnil;

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      call1 (Vrun_hooks, Qcommand_hook_internal);
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      Vpost_command_hook = Vcommand_hook_internal;
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    }
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  /* Do this after running Vpost_command_hook, for consistency.  */
  last_command = this_command;

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  while (1)
    {
      /* Install chars successfully executed in kbd macro.  */

      if (defining_kbd_macro && NILP (Vprefix_arg))
	finalize_kbd_macro_chars ();

      /* Make sure the current window's buffer is selected.  */
      if (XBUFFER (XWINDOW (selected_window)->buffer) != current_buffer)
	set_buffer_internal (XBUFFER (XWINDOW (selected_window)->buffer));

      /* Display any malloc warning that just came out.  Use while because
	 displaying one warning can cause another.  */

      while (pending_malloc_warning)
	display_malloc_warning ();

      no_direct = 0;

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      Vdeactivate_mark = Qnil;

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      /* If minibuffer on and echo area in use,
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	 wait 2 sec and redraw minibuffer.  */
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      if (minibuf_level && echo_area_glyphs)
	{
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	  /* Bind inhibit-quit to t so that C-g gets read in
	     rather than quitting back to the minibuffer.  */
	  int count = specpdl_ptr - specpdl;
	  specbind (Qinhibit_quit, Qt);
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	  Fsit_for (make_number (2), Qnil, Qnil);
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	  unbind_to (count, Qnil);
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	  echo_area_glyphs = 0;
	  no_direct = 1;
	  if (!NILP (Vquit_flag))
	    {
	      Vquit_flag = Qnil;
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	      Vunread_command_events = Fcons (make_number (quit_char), Qnil);
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	    }
	}

#ifdef C_ALLOCA
	  alloca (0);		/* Cause a garbage collection now */
				/* Since we can free the most stuff here.  */
#endif /* C_ALLOCA */

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#if 0
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#ifdef MULTI_FRAME
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      /* Select the frame that the last event came from.  Usually,
	 switch-frame events will take care of this, but if some lisp
	 code swallows a switch-frame event, we'll fix things up here.
	 Is this a good idea?  */
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      if (XTYPE (internal_last_event_frame) == Lisp_Frame
	  && XFRAME (internal_last_event_frame) != selected_frame)
	Fselect_frame (internal_last_event_frame, Qnil);
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#endif
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#endif
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      /* If it has changed current-menubar from previous value,
	 really recompute the menubar from the value.  */
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      if (! NILP (Vlucid_menu_bar_dirty_flag)
	  && !NILP (Ffboundp (Qrecompute_lucid_menubar)))
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	call0 (Qrecompute_lucid_menubar);

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      /* Read next key sequence; i gets its length.  */
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      i = read_key_sequence (keybuf, (sizeof keybuf / sizeof (keybuf[0])), Qnil);
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      ++num_input_keys;

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      /* Now we have read a key sequence of length I,
	 or else I is 0 and we found end of file.  */

      if (i == 0)		/* End of file -- happens only in */
	return Qnil;		/* a kbd macro, at the end.  */
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      /* -1 means read_key_sequence got a menu that was rejected.
	 Just loop around and read another command.  */
      if (i == -1)
	{
	  cancel_echoing ();
	  this_command_key_count = 0;
	  continue;
	}
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      last_command_char = keybuf[i - 1];

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      /* If the previous command tried to force a specific window-start,
	 forget about that, in case this command moves point far away
	 from that position.  */
      XWINDOW (selected_window)->force_start = Qnil;

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      cmd = read_key_sequence_cmd;
      if (!NILP (Vexecuting_macro))
	{
	  if (!NILP (Vquit_flag))
	    {
	      Vexecuting_macro = Qt;
	      QUIT;		/* Make some noise. */
				/* Will return since macro now empty. */
	    }
	}

      /* Do redisplay processing after this command except in special
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	 cases identified below that set no_redisplay to 1.
	 (actually, there's currently no way to prevent the redisplay,
	 and no_redisplay is ignored.
	 Perhaps someday we will really implement it.  */
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      no_redisplay = 0;

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      prev_buffer = current_buffer;
      prev_modiff = MODIFF;
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      last_point_position = PT;
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      XSET (last_point_position_buffer, Lisp_Buffer, prev_buffer);
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      /* Execute the command.  */

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      this_command = cmd;
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      if (!NILP (Vpre_command_hook) && !NILP (Vrun_hooks))
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	{
	  /* If we get an error during the pre-command-hook,
	     cause pre-command-hook to be nil.  */
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	  Vcommand_hook_internal = Vpre_command_hook;
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	  Vpre_command_hook = Qnil;

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	  call1 (Vrun_hooks, Qcommand_hook_internal);
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	  Vpre_command_hook = Vcommand_hook_internal;
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	}
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      if (NILP (this_command))
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	{
	  /* nil means key is undefined.  */
	  bitch_at_user ();
	  defining_kbd_macro = 0;
	  update_mode_lines = 1;
	  Vprefix_arg = Qnil;
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	}
      else
	{
	  if (NILP (Vprefix_arg) && ! no_direct)
	    {
	      /* Recognize some common commands in common situations and
		 do them directly.  */
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	      if (EQ (this_command, Qforward_char) && PT < ZV)
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		{
                  struct Lisp_Vector *dp
		    = window_display_table (XWINDOW (selected_window));
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		  lose = FETCH_CHAR (PT);
		  SET_PT (PT + 1);
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		  if ((dp
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		       ? (VECTORP (DISP_CHAR_VECTOR (dp, lose))
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			  && XVECTOR (DISP_CHAR_VECTOR (dp, lose))->size == 1)
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		       : (lose >= 0x20 && lose < 0x7f))
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		      && (XFASTINT (XWINDOW (selected_window)->last_modified)
			  >= MODIFF)
		      && (XFASTINT (XWINDOW (selected_window)->last_point)
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			  == PT - 1)
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		      && !windows_or_buffers_changed
		      && EQ (current_buffer->selective_display, Qnil)
		      && !detect_input_pending ()
		      && NILP (Vexecuting_macro))
		    no_redisplay = direct_output_forward_char (1);
		  goto directly_done;
		}
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	      else if (EQ (this_command, Qbackward_char) && PT > BEGV)
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		{
                  struct Lisp_Vector *dp
		    = window_display_table (XWINDOW (selected_window));
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		  SET_PT (PT - 1);
		  lose = FETCH_CHAR (PT);
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		  if ((dp
		       ? (XTYPE (DISP_CHAR_VECTOR (dp, lose)) != Lisp_Vector
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			  && XVECTOR (DISP_CHAR_VECTOR (dp, lose))->size == 1)
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		       : (lose >= 0x20 && lose < 0x7f))
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		      && (XFASTINT (XWINDOW (selected_window)->last_modified)
			  >= MODIFF)
		      && (XFASTINT (XWINDOW (selected_window)->last_point)
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			  == PT + 1)
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		      && !windows_or_buffers_changed
		      && EQ (current_buffer->selective_display, Qnil)
		      && !detect_input_pending ()
		      && NILP (Vexecuting_macro))
		    no_redisplay = direct_output_forward_char (-1);
		  goto directly_done;
		}
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	      else if (EQ (this_command, Qself_insert_command)
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		       /* Try this optimization only on ascii keystrokes.  */
		       && XTYPE (last_command_char) == Lisp_Int)
		{
		  unsigned char c = XINT (last_command_char);

		  if (NILP (Vexecuting_macro) &&
		      !EQ (minibuf_window, selected_window))
		    {
		      if (!nonundocount || nonundocount >= 20)
			{
			  Fundo_boundary ();
			  nonundocount = 0;
			}
		      nonundocount++;
		    }
		  lose = (XFASTINT (XWINDOW (selected_window)->last_modified)
			  < MODIFF)
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		    || (XFASTINT (XWINDOW (selected_window)->last_point) != PT)
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		    || MODIFF <= current_buffer->save_modified
		    || windows_or_buffers_changed
		    || !EQ (current_buffer->selective_display, Qnil)
		    || detect_input_pending ()
		    || !NILP (Vexecuting_macro);
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		  if (internal_self_insert (c, 0))
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		    {
		      lose = 1;
		      nonundocount = 0;
		    }
		  if (!lose &&
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		      (PT == ZV || FETCH_CHAR (PT) == '\n'))
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		    {
		      struct Lisp_Vector *dp
			= window_display_table (XWINDOW (selected_window));
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		      int lose = c;
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		      if (dp)
			{
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			  Lisp_Object obj;
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			  obj = DISP_CHAR_VECTOR (dp, lose);
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			  if (XTYPE (obj) == Lisp_Vector
			      && XVECTOR (obj)->size == 1
			      && (XTYPE (obj = XVECTOR (obj)->contents[0])
				  == Lisp_Int))
			    no_redisplay =
			      direct_output_for_insert (XINT (obj));
			}
		      else
			{
			  if (lose >= 0x20 && lose <= 0x7e)
			    no_redisplay = direct_output_for_insert (lose);
			}
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		    }
		  goto directly_done;
		}
	    }

	  /* Here for a command that isn't executed directly */

	  nonundocount = 0;
	  if (NILP (Vprefix_arg))
	    Fundo_boundary ();
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	  Fcommand_execute (this_command, Qnil);
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	}
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    directly_done: ;
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      if (!NILP (Vpost_command_hook) && !NILP (Vrun_hooks))
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	{
	  /* If we get an error during the post-command-hook,
	     cause post-command-hook to be nil.  */
	  Vcommand_hook_internal = Vpost_command_hook;
	  Vpost_command_hook = Qnil;

	  call1 (Vrun_hooks, Qcommand_hook_internal);

	  Vpost_command_hook = Vcommand_hook_internal;
	}
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      /* If there is a prefix argument,
	 1) We don't want last_command to be ``universal-argument''
	 (that would be dumb), so don't set last_command,
	 2) we want to leave echoing on so that the prefix will be
	 echoed as part of this key sequence, so don't call
	 cancel_echoing, and
	 3) we want to leave this_command_key_count non-zero, so that
	 read_char will realize that it is re-reading a character, and
	 not echo it a second time.  */
      if (NILP (Vprefix_arg))
	{
	  last_command = this_command;
	  cancel_echoing ();
	  this_command_key_count = 0;
	}
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      if (!NILP (current_buffer->mark_active) && !NILP (Vrun_hooks))
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	{
	  if (!NILP (Vdeactivate_mark) && !NILP (Vtransient_mark_mode))
	    {
	      current_buffer->mark_active = Qnil;
	      call1 (Vrun_hooks, intern ("deactivate-mark-hook"));
	    }
	  else if (current_buffer != prev_buffer || MODIFF != prev_modiff)
	    call1 (Vrun_hooks, intern ("activate-mark-hook"));
	}
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    }
}

/* Number of seconds between polling for input.  */
int polling_period;

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/* Nonzero means polling for input is temporarily suppressed.  */
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int poll_suppress_count;

#ifdef POLL_FOR_INPUT
int polling_for_input;

/* Handle an alarm once each second and read pending input
   so as to handle a C-g if it comces in.  */

SIGTYPE
input_poll_signal ()
{
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  if (interrupt_input_blocked == 0
      && !waiting_for_input)
    read_avail_input (0);
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  signal (SIGALRM, input_poll_signal);
  alarm (polling_period);
}

#endif

/* Begin signals to poll for input, if they are appropriate.
   This function is called unconditionally from various places.  */

start_polling ()
{
#ifdef POLL_FOR_INPUT
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  if (read_socket_hook && !interrupt_input)
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    {
      poll_suppress_count--;
      if (poll_suppress_count == 0)
	{
	  signal (SIGALRM, input_poll_signal);
	  polling_for_input = 1;
	  alarm (polling_period);
	}
    }
#endif
}

/* Turn off polling.  */

stop_polling ()
{
#ifdef POLL_FOR_INPUT
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  if (read_socket_hook && !interrupt_input)
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    {
      if (poll_suppress_count == 0)
	{
	  polling_for_input = 0;
	  alarm (0);
	}
      poll_suppress_count++;
    }
#endif
}
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