--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/insdel.c	Mon Aug 13 11:28:15 2007 +0200
@@ -0,0 +1,3338 @@
+/* Buffer insertion/deletion and gap motion for XEmacs.
+   Copyright (C) 1985, 1986, 1991, 1992, 1993, 1994, 1995
+   Free Software Foundation, Inc.
+   Copyright (C) 1995 Sun Microsystems, Inc.
+
+This file is part of XEmacs.
+
+XEmacs 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, or (at your option) any
+later version.
+
+XEmacs 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 XEmacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* Synched up with: Mule 2.0, FSF 19.30.  Diverges significantly. */
+
+/* This file has been Mule-ized. */
+
+/* Overhauled by Ben Wing, December 1994, for Mule implementation. */
+
+/*
+   There are three possible ways to specify positions in a buffer.  All
+   of these are one-based: the beginning of the buffer is position or
+   index 1, and 0 is not a valid position.
+
+   As a "buffer position" (typedef Bufpos):
+
+      This is an index specifying an offset in characters from the
+      beginning of the buffer.  Note that buffer positions are
+      logically *between* characters, not on a character.  The
+      difference between two buffer positions specifies the number of
+      characters between those positions.  Buffer positions are the
+      only kind of position externally visible to the user.
+
+   As a "byte index" (typedef Bytind):
+
+      This is an index over the bytes used to represent the characters
+      in the buffer.  If there is no Mule support, this is identical
+      to a buffer position, because each character is represented
+      using one byte.  However, with Mule support, many characters
+      require two or more bytes for their representation, and so a
+      byte index may be greater than the corresponding buffer
+      position.
+
+   As a "memory index" (typedef Memind):
+
+      This is the byte index adjusted for the gap.  For positions
+      before the gap, this is identical to the byte index.  For
+      positions after the gap, this is the byte index plus the gap
+      size.  There are two possible memory indices for the gap
+      position; the memory index at the beginning of the gap should
+      always be used, except in code that deals with manipulating the
+      gap, where both indices may be seen.  The address of the
+      character "at" (i.e. following) a particular position can be
+      obtained from the formula
+
+        buffer_start_address + memory_index(position) - 1
+
+      except in the case of characters at the gap position.
+
+   Other typedefs:
+   ===============
+
+      Emchar:
+      -------
+        This typedef represents a single Emacs character, which can be
+	ASCII, ISO-8859, or some extended character, as would typically
+	be used for Kanji.  Note that the representation of a character
+	as an Emchar is *not* the same as the representation of that
+	same character in a string; thus, you cannot do the standard
+	C trick of passing a pointer to a character to a function that
+	expects a string.
+
+	An Emchar takes up 19 bits of representation and (for code
+	compatibility and such) is compatible with an int.  This
+	representation is visible on the Lisp level.  The important
+	characteristics	of the Emchar representation are
+
+	  -- values 0x00 - 0x7f represent ASCII.
+	  -- values 0x80 - 0xff represent the right half of ISO-8859-1.
+	  -- values 0x100 and up represent all other characters.
+
+	This means that Emchar values are upwardly compatible with
+	the standard 8-bit representation of ASCII/ISO-8859-1.
+
+      Bufbyte:
+      --------
+        The data in a buffer or string is logically made up of Bufbyte
+	objects, where a Bufbyte takes up the same amount of space as a
+	char. (It is declared differently, though, to catch invalid
+	usages.) Strings stored using Bufbytes are said to be in
+	"internal format".  The important characteristics of internal
+	format are
+
+	  -- ASCII characters are represented as a single Bufbyte,
+	     in the range 0 - 0x7f.
+	  -- All other characters are represented as a Bufbyte in
+	     the range 0x80 - 0x9f followed by one or more Bufbytes
+	     in the range 0xa0 to 0xff.
+
+	This leads to a number of desirable properties:
+
+	  -- Given the position of the beginning of a character,
+	     you can find the beginning of the next or previous
+	     character in constant time.
+	  -- When searching for a substring or an ASCII character
+	     within the string, you need merely use standard
+	     searching routines.
+
+      array of char:
+      --------------
+        Strings that go in or out of Emacs are in "external format",
+	typedef'ed as an array of char or a char *.  There is more
+	than one external format (JIS, EUC, etc.) but they all
+	have similar properties.  They are modal encodings,
+	which is to say that the meaning of particular bytes is
+	not fixed but depends on what "mode" the string is currently
+	in (e.g. bytes in the range 0 - 0x7f might be
+	interpreted as ASCII, or as Hiragana, or as 2-byte Kanji,
+	depending on the current mode).  The mode starts out in
+	ASCII/ISO-8859-1 and is switched using escape sequences --
+	for example, in the JIS encoding, 'ESC $ B' switches to a
+	mode where pairs of bytes in the range 0 - 0x7f
+	are interpreted as Kanji characters.
+
+	External-formatted data is generally desirable for passing
+	data between programs because it is upwardly compatible
+	with standard ASCII/ISO-8859-1 strings and may require
+	less space than internal encodings such as the one
+	described above.  In addition, some encodings (e.g. JIS)
+	keep all characters (except the ESC used to switch modes)
+	in the printing ASCII range 0x20 - 0x7e, which results in
+	a much higher probability that the data will avoid being
+	garbled in transmission.  Externally-formatted data is
+	generally not very convenient to work with, however, and
+	for this reason is usually converted to internal format
+	before any work is done on the string.
+
+	NOTE: filenames need to be in external format so that
+	ISO-8859-1 characters come out correctly.
+
+      Charcount:
+      ----------
+        This typedef represents a count of characters, such as
+	a character offset into a string or the number of
+	characters between two positions in a buffer.  The
+	difference between two Bufpos's is a Charcount, and
+	character positions in a string are represented using
+	a Charcount.
+
+      Bytecount:
+      ----------
+        Similar to a Charcount but represents a count of bytes.
+	The difference between two Bytind's is a Bytecount.
+
+
+   Usage of the various representations:
+   =====================================
+
+   Memory indices are used in low-level functions in insdel.c and for
+   extent endpoints and marker positions.  The reason for this is that
+   this way, the extents and markers don't need to be updated for most
+   insertions, which merely shrink the gap and don't move any
+   characters around in memory.
+
+   (The beginning-of-gap memory index simplifies insertions w.r.t.
+   markers, because text usually gets inserted after markers.  For
+   extents, it is merely for consistency, because text can get
+   inserted either before or after an extent's endpoint depending on
+   the open/closedness of the endpoint.)
+
+   Byte indices are used in other code that needs to be fast,
+   such as the searching, redisplay, and extent-manipulation code.
+
+   Buffer positions are used in all other code.  This is because this
+   representation is easiest to work with (especially since Lisp
+   code always uses buffer positions), necessitates the fewest
+   changes to existing code, and is the safest (e.g. if the text gets
+   shifted underneath a buffer position, it will still point to a
+   character; if text is shifted under a byte index, it might point
+   to the middle of a character, which would be bad).
+
+   Similarly, Charcounts are used in all code that deals with strings
+   except for code that needs to be fast, which used Bytecounts.
+
+   Strings are always passed around internally using internal format.
+   Conversions between external format are performed at the time
+   that the data goes in or out of Emacs.
+
+   Working with the various representations:
+   ========================================= */
+
+#include <config.h>
+#include "lisp.h"
+#include <limits.h>
+
+#include "buffer.h"
+#include "device.h"
+#include "frame.h"
+#include "extents.h"
+#include "insdel.h"
+#include "lstream.h"
+#include "redisplay.h"
+#include "line-number.h"
+
+/* We write things this way because it's very important the
+   MAX_BYTIND_GAP_SIZE_3 is a multiple of 3. (As it happens,
+   65535 is a multiple of 3, but this may not always be the
+   case.) */
+
+#define MAX_BUFPOS_GAP_SIZE_3 (65535/3)
+#define MAX_BYTIND_GAP_SIZE_3 (3 * MAX_BUFPOS_GAP_SIZE_3)
+
+short three_to_one_table[1 + MAX_BYTIND_GAP_SIZE_3];
+
+/* Various macros modelled along the lines of those in buffer.h.
+   Purposefully omitted from buffer.h because files other than this
+   one should not be using them. */
+
+/* Address of beginning of buffer.  This is an lvalue because
+   BUFFER_ALLOC needs it to be. */
+#define BUF_BEG_ADDR(buf) ((buf)->text->beg)
+
+/* Set the address of beginning of buffer. */
+#define SET_BUF_BEG_ADDR(buf, addr) do { (buf)->text->beg = (addr); } while (0)
+
+/* Gap size.  */
+#define BUF_GAP_SIZE(buf) ((buf)->text->gap_size + 0)
+#define BUF_END_GAP_SIZE(buf) ((buf)->text->end_gap_size + 0)
+/* Set gap size.  */
+#define SET_BUF_GAP_SIZE(buf, value) \
+  do { (buf)->text->gap_size = (value); } while (0)
+#define SET_BUF_END_GAP_SIZE(buf, value) \
+  do { (buf)->text->end_gap_size = (value); } while (0)
+
+/* Gap location.  */
+#define BI_BUF_GPT(buf) ((buf)->text->gpt + 0)
+#define BUF_GPT_ADDR(buf) (BUF_BEG_ADDR (buf) + BI_BUF_GPT (buf) - 1)
+
+/* Set gap location.  */
+#define SET_BI_BUF_GPT(buf, value) do { (buf)->text->gpt = (value); } while (0)
+
+/* Set end of buffer.  */
+#define SET_BOTH_BUF_Z(buf, val, bival)		\
+do						\
+{						\
+  (buf)->text->z = (bival);			\
+  (buf)->text->bufz = (val);			\
+} while (0)
+
+/* Under Mule, we maintain two sentinels in the buffer: one at the
+   beginning of the gap, and one at the end of the buffer.  This
+   allows us to move forward, examining bytes looking for the
+   end of a character, and not worry about running off the end.
+   We do not need corresponding sentinels when moving backwards
+   because we do not have to look past the beginning of a character
+   to find the beginning of the character.
+
+   Every time we change the beginning of the gap, we have to
+   call SET_GAP_SENTINEL().
+
+   Every time we change the total size (characters plus gap)
+   of the buffer, we have to call SET_END_SENTINEL().
+ */
+
+
+#ifdef MULE
+# define GAP_CAN_HOLD_SIZE_P(buf, len) (BUF_GAP_SIZE (buf) >= (len) + 1)
+# define SET_GAP_SENTINEL(buf) (*BUF_GPT_ADDR (buf) = 0)
+# define BUF_END_SENTINEL_SIZE 1
+# define SET_END_SENTINEL(buf) \
+  (*(BUF_BEG_ADDR (buf) + BUF_GAP_SIZE (buf) + BI_BUF_Z (buf) - 1) = 0)
+#else
+# define GAP_CAN_HOLD_SIZE_P(buf, len) (BUF_GAP_SIZE (buf) >= (len))
+# define SET_GAP_SENTINEL(buf)
+# define BUF_END_SENTINEL_SIZE 0
+# define SET_END_SENTINEL(buf)
+#endif
+
+
+/************************************************************************/
+/*                    Charcount/Bytecount conversion                    */
+/************************************************************************/
+
+/* Optimization.  Do it.  Live it.  Love it.  */
+
+#ifdef MULE
+
+/* We include the basic functions here that require no specific
+   knowledge of how data is Mule-encoded into a buffer other
+   than the basic (00 - 7F), (80 - 9F), (A0 - FF) scheme.
+   Anything that requires more specific knowledge goes into
+   mule-charset.c. */
+
+/* Given a pointer to a text string and a length in bytes, return
+   the equivalent length in characters. */
+
+Charcount
+bytecount_to_charcount (CONST Bufbyte *ptr, Bytecount len)
+{
+  Charcount count = 0;
+  CONST Bufbyte *end = ptr + len;
+
+#if (LONGBITS == 32 || LONGBITS == 64)
+
+# if (LONGBITS == 32)
+#  define LONG_BYTES 4
+#  define ALIGN_MASK 0xFFFFFFFCU
+#  define HIGH_BIT_MASK 0x80808080U
+# else
+#  define LONG_BYTES 8
+#  define ALIGN_MASK 0xFFFFFFFFFFFFFFF8UL
+   /* I had a dream, I was being overrun with early Intel processors ... */
+#  define HIGH_BIT_MASK 0x8080808080808080UL
+# endif
+
+  /* When we have a large number of bytes to scan, we can be trickier
+     and significantly faster by scanning them in chunks of the CPU word
+     size (assuming that they're all ASCII -- we cut out as soon as
+     we find something non-ASCII). */
+  if (len >= 12)
+    {
+      /* Determine the section in the middle of the string that's
+	 amenable to this treatment.  Everything has to be aligned
+	 on CPU word boundaries. */
+      CONST Bufbyte *aligned_ptr =
+	(CONST Bufbyte *) (((unsigned long) (ptr + LONG_BYTES - 1)) &
+			   ALIGN_MASK);
+      CONST Bufbyte *aligned_end =
+	(CONST Bufbyte *) (((unsigned long) end) & ALIGN_MASK);
+
+      /* Handle unaligned stuff at the beginning. */
+      while (ptr < aligned_ptr)
+	{
+	  if (!BYTE_ASCII_P (*ptr))
+	    goto bail;
+	  count++, ptr++;
+	}
+      /* Now do it. */
+      while (ptr < aligned_end)
+	{
+
+	  if ((* (unsigned long *) ptr) & HIGH_BIT_MASK)
+	    goto bail;
+	  ptr += LONG_BYTES;
+	  count += LONG_BYTES;
+	}
+    }
+
+#endif /* LONGBITS == 32 || LONGBITS == 64 */
+
+ bail:
+  while (ptr < end)
+    {
+      count++;
+      INC_CHARPTR (ptr);
+    }
+#ifdef ERROR_CHECK_BUFPOS
+  /* Bomb out if the specified substring ends in the middle
+     of a character.  Note that we might have already gotten
+     a core dump above from an invalid reference, but at least
+     we will get no farther than here. */
+  assert (ptr == end);
+#endif
+
+  return count;
+}
+
+/* Given a pointer to a text string and a length in characters, return
+   the equivalent length in bytes. */
+
+Bytecount
+charcount_to_bytecount (CONST Bufbyte *ptr, Charcount len)
+{
+  CONST Bufbyte *newptr = ptr;
+
+  while (len > 0)
+    {
+      INC_CHARPTR (newptr);
+      len--;
+    }
+  return newptr - ptr;
+}
+
+/* The next two functions are the actual meat behind the
+   bufpos-to-bytind and bytind-to-bufpos conversions.  Currently
+   the method they use is fairly unsophisticated; see buffer.h.
+
+   Note that bufpos_to_bytind_func() is probably the most-called
+   function in all of XEmacs.  Therefore, it must be FAST FAST FAST.
+   This is the reason why so much of the code is duplicated.
+
+   Similar considerations apply to bytind_to_bufpos_func(), although
+   less so because the function is not called so often.
+
+   #### At some point this should use a more sophisticated method;
+   see buffer.h. */
+
+static int not_very_random_number;
+
+Bytind
+bufpos_to_bytind_func (struct buffer *buf, Bufpos x)
+{
+  Bufpos bufmin;
+  Bufpos bufmax;
+  Bytind bytmin;
+  Bytind bytmax;
+  int size;
+  int forward_p;
+  Bytind retval;
+  int diff_so_far;
+  int add_to_cache = 0;
+
+  /* Check for some cached positions, for speed. */
+  if (x == BUF_PT (buf))
+    return BI_BUF_PT (buf);
+  if (x == BUF_ZV (buf))
+    return BI_BUF_ZV (buf);
+  if (x == BUF_BEGV (buf))
+    return BI_BUF_BEGV (buf);
+
+  bufmin = buf->text->mule_bufmin;
+  bufmax = buf->text->mule_bufmax;
+  bytmin = buf->text->mule_bytmin;
+  bytmax = buf->text->mule_bytmax;
+  size = (1 << buf->text->mule_shifter) + !!buf->text->mule_three_p;
+
+  /* The basic idea here is that we shift the "known region" up or down
+     until it overlaps the specified position.  We do this by moving
+     the upper bound of the known region up one character at a time,
+     and moving the lower bound of the known region up as necessary
+     when the size of the character just seen changes.
+
+     We optimize this, however, by first shifting the known region to
+     one of the cached points if it's close by. (We don't check BEG or
+     Z, even though they're cached; most of the time these will be the
+     same as BEGV and ZV, and when they're not, they're not likely
+     to be used.) */
+
+  if (x > bufmax)
+    {
+      Bufpos diffmax = x - bufmax;
+      Bufpos diffpt = x - BUF_PT (buf);
+      Bufpos diffzv = BUF_ZV (buf) - x;
+      /* #### This value could stand some more exploration. */
+      Charcount heuristic_hack = (bufmax - bufmin) >> 2;
+
+      /* Check if the position is closer to PT or ZV than to the
+	 end of the known region. */
+
+      if (diffpt < 0)
+	diffpt = -diffpt;
+      if (diffzv < 0)
+	diffzv = -diffzv;
+
+      /* But also implement a heuristic that favors the known region
+	 over PT or ZV.  The reason for this is that switching to
+	 PT or ZV will wipe out the knowledge in the known region,
+	 which might be annoying if the known region is large and
+	 PT or ZV is not that much closer than the end of the known
+	 region. */
+
+      diffzv += heuristic_hack;
+      diffpt += heuristic_hack;
+      if (diffpt < diffmax && diffpt <= diffzv)
+	{
+	  bufmax = bufmin = BUF_PT (buf);
+	  bytmax = bytmin = BI_BUF_PT (buf);
+	  /* We set the size to 1 even though it doesn't really
+	     matter because the new known region contains no
+	     characters.  We do this because this is the most
+	     likely size of the characters around the new known
+	     region, and we avoid potential yuckiness that is
+	     done when size == 3. */
+	  size = 1;
+	}
+      if (diffzv < diffmax)
+	{
+	  bufmax = bufmin = BUF_ZV (buf);
+	  bytmax = bytmin = BI_BUF_ZV (buf);
+	  size = 1;
+	}
+    }
+#ifdef ERROR_CHECK_BUFPOS
+  else if (x >= bufmin)
+    abort ();
+#endif
+  else
+    {
+      Bufpos diffmin = bufmin - x;
+      Bufpos diffpt = BUF_PT (buf) - x;
+      Bufpos diffbegv = x - BUF_BEGV (buf);
+      /* #### This value could stand some more exploration. */
+      Charcount heuristic_hack = (bufmax - bufmin) >> 2;
+
+      if (diffpt < 0)
+	diffpt = -diffpt;
+      if (diffbegv < 0)
+	diffbegv = -diffbegv;
+
+      /* But also implement a heuristic that favors the known region --
+	 see above. */
+
+      diffbegv += heuristic_hack;
+      diffpt += heuristic_hack;
+
+      if (diffpt < diffmin && diffpt <= diffbegv)
+	{
+	  bufmax = bufmin = BUF_PT (buf);
+	  bytmax = bytmin = BI_BUF_PT (buf);
+	  /* We set the size to 1 even though it doesn't really
+	     matter because the new known region contains no
+	     characters.  We do this because this is the most
+	     likely size of the characters around the new known
+	     region, and we avoid potential yuckiness that is
+	     done when size == 3. */
+	  size = 1;
+	}
+      if (diffbegv < diffmin)
+	{
+	  bufmax = bufmin = BUF_BEGV (buf);
+	  bytmax = bytmin = BI_BUF_BEGV (buf);
+	  size = 1;
+	}
+    }
+
+  diff_so_far = x > bufmax ? x - bufmax : bufmin - x;
+  if (diff_so_far > 50)
+    {
+      /* If we have to move more than a certain amount, then look
+	 into our cache. */
+      int minval = INT_MAX;
+      int found = 0;
+      int i;
+
+      add_to_cache = 1;
+      /* I considered keeping the positions ordered.  This would speed
+	 up this loop, but updating the cache would take longer, so
+	 it doesn't seem like it would really matter. */
+      for (i = 0; i < 16; i++)
+	{
+	  int diff = buf->text->mule_bufpos_cache[i] - x;
+
+	  if (diff < 0)
+	    diff = -diff;
+	  if (diff < minval)
+	    {
+	      minval = diff;
+	      found = i;
+	    }
+	}
+
+      if (minval < diff_so_far)
+	{
+	  bufmax = bufmin = buf->text->mule_bufpos_cache[found];
+	  bytmax = bytmin = buf->text->mule_bytind_cache[found];
+	  size = 1;
+	}
+    }
+
+  /* It's conceivable that the caching above could lead to X being
+     the same as one of the range edges. */
+  if (x >= bufmax)
+    {
+      Bytind newmax;
+      Bytecount newsize;
+
+      forward_p = 1;
+      while (x > bufmax)
+	{
+	  newmax = bytmax;
+
+	  INC_BYTIND (buf, newmax);
+	  newsize = newmax - bytmax;
+	  if (newsize != size)
+	    {
+	      bufmin = bufmax;
+	      bytmin = bytmax;
+	      size = newsize;
+	    }
+	  bytmax = newmax;
+	  bufmax++;
+	}
+      retval = bytmax;
+
+      /* #### Should go past the found location to reduce the number
+	 of times that this function is called */
+    }
+  else /* x < bufmin */
+    {
+      Bytind newmin;
+      Bytecount newsize;
+
+      forward_p = 0;
+      while (x < bufmin)
+	{
+	  newmin = bytmin;
+
+	  DEC_BYTIND (buf, newmin);
+	  newsize = bytmin - newmin;
+	  if (newsize != size)
+	    {
+	      bufmax = bufmin;
+	      bytmax = bytmin;
+	      size = newsize;
+	    }
+	  bytmin = newmin;
+	  bufmin--;
+	}
+      retval = bytmin;
+
+      /* #### Should go past the found location to reduce the number
+	 of times that this function is called
+         */
+    }
+
+  /* If size is three, than we have to max sure that the range we
+     discovered isn't too large, because we use a fixed-length
+     table to divide by 3. */
+
+  if (size == 3)
+    {
+      int gap = bytmax - bytmin;
+      buf->text->mule_three_p = 1;
+      buf->text->mule_shifter = 1;
+
+      if (gap > MAX_BYTIND_GAP_SIZE_3)
+	{
+	  if (forward_p)
+	    {
+	      bytmin = bytmax - MAX_BYTIND_GAP_SIZE_3;
+	      bufmin = bufmax - MAX_BUFPOS_GAP_SIZE_3;
+	    }
+	  else
+	    {
+	      bytmax = bytmin + MAX_BYTIND_GAP_SIZE_3;
+	      bufmax = bufmin + MAX_BUFPOS_GAP_SIZE_3;
+	    }
+	}
+    }
+  else
+    {
+      buf->text->mule_three_p = 0;
+      if (size == 4)
+	buf->text->mule_shifter = 2;
+      else
+	buf->text->mule_shifter = size - 1;
+    }
+
+  buf->text->mule_bufmin = bufmin;
+  buf->text->mule_bufmax = bufmax;
+  buf->text->mule_bytmin = bytmin;
+  buf->text->mule_bytmax = bytmax;
+
+  if (add_to_cache)
+    {
+      int replace_loc;
+
+      /* We throw away a "random" cached value and replace it with
+	 the new value.  It doesn't actually have to be very random
+	 at all, just evenly distributed.
+
+	 #### It would be better to use a least-recently-used algorithm
+	 or something that tries to space things out, but I'm not sure
+	 it's worth it to go to the trouble of maintaining that. */
+      not_very_random_number += 621;
+      replace_loc = not_very_random_number & 15;
+      buf->text->mule_bufpos_cache[replace_loc] = x;
+      buf->text->mule_bytind_cache[replace_loc] = retval;
+    }
+
+  return retval;
+}
+
+/* The logic in this function is almost identical to the logic in
+   the previous function. */
+
+Bufpos
+bytind_to_bufpos_func (struct buffer *buf, Bytind x)
+{
+  Bufpos bufmin;
+  Bufpos bufmax;
+  Bytind bytmin;
+  Bytind bytmax;
+  int size;
+  int forward_p;
+  Bufpos retval;
+  int diff_so_far;
+  int add_to_cache = 0;
+
+  /* Check for some cached positions, for speed. */
+  if (x == BI_BUF_PT (buf))
+    return BUF_PT (buf);
+  if (x == BI_BUF_ZV (buf))
+    return BUF_ZV (buf);
+  if (x == BI_BUF_BEGV (buf))
+    return BUF_BEGV (buf);
+
+  bufmin = buf->text->mule_bufmin;
+  bufmax = buf->text->mule_bufmax;
+  bytmin = buf->text->mule_bytmin;
+  bytmax = buf->text->mule_bytmax;
+  size = (1 << buf->text->mule_shifter) + !!buf->text->mule_three_p;
+
+  /* The basic idea here is that we shift the "known region" up or down
+     until it overlaps the specified position.  We do this by moving
+     the upper bound of the known region up one character at a time,
+     and moving the lower bound of the known region up as necessary
+     when the size of the character just seen changes.
+
+     We optimize this, however, by first shifting the known region to
+     one of the cached points if it's close by. (We don't check BI_BEG or
+     BI_Z, even though they're cached; most of the time these will be the
+     same as BI_BEGV and BI_ZV, and when they're not, they're not likely
+     to be used.) */
+
+  if (x > bytmax)
+    {
+      Bytind diffmax = x - bytmax;
+      Bytind diffpt = x - BI_BUF_PT (buf);
+      Bytind diffzv = BI_BUF_ZV (buf) - x;
+      /* #### This value could stand some more exploration. */
+      Bytecount heuristic_hack = (bytmax - bytmin) >> 2;
+
+      /* Check if the position is closer to PT or ZV than to the
+	 end of the known region. */
+
+      if (diffpt < 0)
+	diffpt = -diffpt;
+      if (diffzv < 0)
+	diffzv = -diffzv;
+
+      /* But also implement a heuristic that favors the known region
+	 over BI_PT or BI_ZV.  The reason for this is that switching to
+	 BI_PT or BI_ZV will wipe out the knowledge in the known region,
+	 which might be annoying if the known region is large and
+	 BI_PT or BI_ZV is not that much closer than the end of the known
+	 region. */
+
+      diffzv += heuristic_hack;
+      diffpt += heuristic_hack;
+      if (diffpt < diffmax && diffpt <= diffzv)
+	{
+	  bufmax = bufmin = BUF_PT (buf);
+	  bytmax = bytmin = BI_BUF_PT (buf);
+	  /* We set the size to 1 even though it doesn't really
+	     matter because the new known region contains no
+	     characters.  We do this because this is the most
+	     likely size of the characters around the new known
+	     region, and we avoid potential yuckiness that is
+	     done when size == 3. */
+	  size = 1;
+	}
+      if (diffzv < diffmax)
+	{
+	  bufmax = bufmin = BUF_ZV (buf);
+	  bytmax = bytmin = BI_BUF_ZV (buf);
+	  size = 1;
+	}
+    }
+#ifdef ERROR_CHECK_BUFPOS
+  else if (x >= bytmin)
+    abort ();
+#endif
+  else
+    {
+      Bytind diffmin = bytmin - x;
+      Bytind diffpt = BI_BUF_PT (buf) - x;
+      Bytind diffbegv = x - BI_BUF_BEGV (buf);
+      /* #### This value could stand some more exploration. */
+      Bytecount heuristic_hack = (bytmax - bytmin) >> 2;
+
+      if (diffpt < 0)
+	diffpt = -diffpt;
+      if (diffbegv < 0)
+	diffbegv = -diffbegv;
+
+      /* But also implement a heuristic that favors the known region --
+	 see above. */
+
+      diffbegv += heuristic_hack;
+      diffpt += heuristic_hack;
+
+      if (diffpt < diffmin && diffpt <= diffbegv)
+	{
+	  bufmax = bufmin = BUF_PT (buf);
+	  bytmax = bytmin = BI_BUF_PT (buf);
+	  /* We set the size to 1 even though it doesn't really
+	     matter because the new known region contains no
+	     characters.  We do this because this is the most
+	     likely size of the characters around the new known
+	     region, and we avoid potential yuckiness that is
+	     done when size == 3. */
+	  size = 1;
+	}
+      if (diffbegv < diffmin)
+	{
+	  bufmax = bufmin = BUF_BEGV (buf);
+	  bytmax = bytmin = BI_BUF_BEGV (buf);
+	  size = 1;
+	}
+    }
+
+  diff_so_far = x > bytmax ? x - bytmax : bytmin - x;
+  if (diff_so_far > 50)
+    {
+      /* If we have to move more than a certain amount, then look
+	 into our cache. */
+      int minval = INT_MAX;
+      int found = 0;
+      int i;
+
+      add_to_cache = 1;
+      /* I considered keeping the positions ordered.  This would speed
+	 up this loop, but updating the cache would take longer, so
+	 it doesn't seem like it would really matter. */
+      for (i = 0; i < 16; i++)
+	{
+	  int diff = buf->text->mule_bytind_cache[i] - x;
+
+	  if (diff < 0)
+	    diff = -diff;
+	  if (diff < minval)
+	    {
+	      minval = diff;
+	      found = i;
+	    }
+	}
+
+      if (minval < diff_so_far)
+	{
+	  bufmax = bufmin = buf->text->mule_bufpos_cache[found];
+	  bytmax = bytmin = buf->text->mule_bytind_cache[found];
+	  size = 1;
+	}
+    }
+
+  /* It's conceivable that the caching above could lead to X being
+     the same as one of the range edges. */
+  if (x >= bytmax)
+    {
+      Bytind newmax;
+      Bytecount newsize;
+
+      forward_p = 1;
+      while (x > bytmax)
+	{
+	  newmax = bytmax;
+
+	  INC_BYTIND (buf, newmax);
+	  newsize = newmax - bytmax;
+	  if (newsize != size)
+	    {
+	      bufmin = bufmax;
+	      bytmin = bytmax;
+	      size = newsize;
+	    }
+	  bytmax = newmax;
+	  bufmax++;
+	}
+      retval = bufmax;
+
+      /* #### Should go past the found location to reduce the number
+	 of times that this function is called */
+    }
+  else /* x <= bytmin */
+    {
+      Bytind newmin;
+      Bytecount newsize;
+
+      forward_p = 0;
+      while (x < bytmin)
+	{
+	  newmin = bytmin;
+
+	  DEC_BYTIND (buf, newmin);
+	  newsize = bytmin - newmin;
+	  if (newsize != size)
+	    {
+	      bufmax = bufmin;
+	      bytmax = bytmin;
+	      size = newsize;
+	    }
+	  bytmin = newmin;
+	  bufmin--;
+	}
+      retval = bufmin;
+
+      /* #### Should go past the found location to reduce the number
+	 of times that this function is called
+         */
+    }
+
+  /* If size is three, than we have to max sure that the range we
+     discovered isn't too large, because we use a fixed-length
+     table to divide by 3. */
+
+  if (size == 3)
+    {
+      int gap = bytmax - bytmin;
+      buf->text->mule_three_p = 1;
+      buf->text->mule_shifter = 1;
+
+      if (gap > MAX_BYTIND_GAP_SIZE_3)
+	{
+	  if (forward_p)
+	    {
+	      bytmin = bytmax - MAX_BYTIND_GAP_SIZE_3;
+	      bufmin = bufmax - MAX_BUFPOS_GAP_SIZE_3;
+	    }
+	  else
+	    {
+	      bytmax = bytmin + MAX_BYTIND_GAP_SIZE_3;
+	      bufmax = bufmin + MAX_BUFPOS_GAP_SIZE_3;
+	    }
+	}
+    }
+  else
+    {
+      buf->text->mule_three_p = 0;
+      if (size == 4)
+	buf->text->mule_shifter = 2;
+      else
+	buf->text->mule_shifter = size - 1;
+    }
+
+  buf->text->mule_bufmin = bufmin;
+  buf->text->mule_bufmax = bufmax;
+  buf->text->mule_bytmin = bytmin;
+  buf->text->mule_bytmax = bytmax;
+
+  if (add_to_cache)
+    {
+      int replace_loc;
+
+      /* We throw away a "random" cached value and replace it with
+	 the new value.  It doesn't actually have to be very random
+	 at all, just evenly distributed.
+
+	 #### It would be better to use a least-recently-used algorithm
+	 or something that tries to space things out, but I'm not sure
+	 it's worth it to go to the trouble of maintaining that. */
+      not_very_random_number += 621;
+      replace_loc = not_very_random_number & 15;
+      buf->text->mule_bufpos_cache[replace_loc] = retval;
+      buf->text->mule_bytind_cache[replace_loc] = x;
+    }
+
+  return retval;
+}
+
+/* Text of length BYTELENGTH and CHARLENGTH (in different units)
+   was inserted at bufpos START. */
+
+static void
+buffer_mule_signal_inserted_region (struct buffer *buf, Bufpos start,
+				    Bytecount bytelength,
+				    Charcount charlength)
+{
+  int size = (1 << buf->text->mule_shifter) + !!buf->text->mule_three_p;
+  int i;
+
+  /* Adjust the cache of known positions. */
+  for (i = 0; i < 16; i++)
+    {
+
+      if (buf->text->mule_bufpos_cache[i] > start)
+	{
+	  buf->text->mule_bufpos_cache[i] += charlength;
+	  buf->text->mule_bytind_cache[i] += bytelength;
+	}
+    }
+
+  if (start >= buf->text->mule_bufmax)
+    return;
+
+  /* The insertion is either before the known region, in which case
+     it shoves it forward; or within the known region, in which case
+     it shoves the end forward. (But it may make the known region
+     inconsistent, so we may have to shorten it.) */
+
+  if (start <= buf->text->mule_bufmin)
+    {
+      buf->text->mule_bufmin += charlength;
+      buf->text->mule_bufmax += charlength;
+      buf->text->mule_bytmin += bytelength;
+      buf->text->mule_bytmax += bytelength;
+    }
+  else
+    {
+      Bufpos end = start + charlength;
+      /* the insertion point divides the known region in two.
+	 Keep the longer half, at least, and expand into the
+	 inserted chunk as much as possible. */
+
+      if (start - buf->text->mule_bufmin > buf->text->mule_bufmax - start)
+	{
+	  Bytind bytestart = (buf->text->mule_bytmin
+			      + size * (start - buf->text->mule_bufmin));
+	  Bytind bytenew;
+
+	  while (start < end)
+	    {
+	      bytenew = bytestart;
+	      INC_BYTIND (buf, bytenew);
+	      if (bytenew - bytestart != size)
+		break;
+	      start++;
+              bytestart = bytenew;
+	    }
+	  if (start != end)
+	    {
+	      buf->text->mule_bufmax = start;
+	      buf->text->mule_bytmax = bytestart;
+	    }
+	  else
+	    {
+	      buf->text->mule_bufmax += charlength;
+	      buf->text->mule_bytmax += bytelength;
+	    }
+	}
+      else
+	{
+	  Bytind byteend = (buf->text->mule_bytmin
+			    + size * (start - buf->text->mule_bufmin)
+			    + bytelength);
+	  Bytind bytenew;
+
+	  buf->text->mule_bufmax += charlength;
+	  buf->text->mule_bytmax += bytelength;
+
+	  while (end > start)
+	    {
+	      bytenew = byteend;
+	      DEC_BYTIND (buf, bytenew);
+	      if (byteend - bytenew != size)
+		break;
+	      end--;
+              byteend = bytenew;
+	    }
+	  if (start != end)
+	    {
+	      buf->text->mule_bufmin = end;
+	      buf->text->mule_bytmin = byteend;
+	    }
+	}
+    }
+}
+
+/* Text from START to END (equivalent in Bytinds: from BI_START to
+   BI_END) was deleted. */
+
+static void
+buffer_mule_signal_deleted_region (struct buffer *buf, Bufpos start,
+				   Bufpos end, Bytind bi_start,
+				   Bytind bi_end)
+{
+  int i;
+
+  /* Adjust the cache of known positions. */
+  for (i = 0; i < 16; i++)
+    {
+      /* After the end; gets shoved backward */
+      if (buf->text->mule_bufpos_cache[i] > end)
+	{
+	  buf->text->mule_bufpos_cache[i] -= end - start;
+	  buf->text->mule_bytind_cache[i] -= bi_end - bi_start;
+	}
+      /* In the range; moves to start of range */
+      else if (buf->text->mule_bufpos_cache[i] > start)
+	{
+	  buf->text->mule_bufpos_cache[i] = start;
+	  buf->text->mule_bytind_cache[i] = bi_start;
+	}
+    }
+
+  /* We don't care about any text after the end of the known region. */
+
+  end = min (end, buf->text->mule_bufmax);
+  bi_end = min (bi_end, buf->text->mule_bytmax);
+  if (start >= end)
+    return;
+
+  /* The end of the known region offsets by the total amount of deletion,
+     since it's all before it. */
+
+  buf->text->mule_bufmax -= end - start;
+  buf->text->mule_bytmax -= bi_end - bi_start;
+
+  /* Now we don't care about any text after the start of the known region. */
+
+  end = min (end, buf->text->mule_bufmin);
+  bi_end = min (bi_end, buf->text->mule_bytmin);
+  if (start >= end)
+    return;
+
+  buf->text->mule_bufmin -= end - start;
+  buf->text->mule_bytmin -= bi_end - bi_start;
+}
+
+#endif /* MULE */
+
+#ifdef ERROR_CHECK_BUFPOS
+
+Bytind
+bufpos_to_bytind (struct buffer *buf, Bufpos x)
+{
+  Bytind retval = real_bufpos_to_bytind (buf, x);
+  ASSERT_VALID_BYTIND_UNSAFE (buf, retval);
+  return retval;
+}
+
+Bufpos
+bytind_to_bufpos (struct buffer *buf, Bytind x)
+{
+  ASSERT_VALID_BYTIND_UNSAFE (buf, x);
+  return real_bytind_to_bufpos (buf, x);
+}
+
+#endif /* ERROR_CHECK_BUFPOS */
+
+
+/************************************************************************/
+/*                verifying buffer and string positions                 */
+/************************************************************************/
+
+/* Functions below are tagged with either _byte or _char indicating
+   whether they return byte or character positions.  For a buffer,
+   a character position is a "Bufpos" and a byte position is a "Bytind".
+   For strings, these are sometimes typed using "Charcount" and
+   "Bytecount". */
+
+/* Flags for the functions below are:
+
+   GB_ALLOW_PAST_ACCESSIBLE
+
+     Allow positions to range over the entire buffer (BUF_BEG to BUF_Z),
+     rather than just the accessible portion (BUF_BEGV to BUF_ZV).
+     For strings, this flag has no effect.
+
+   GB_COERCE_RANGE
+
+     If the position is outside the allowable range, return the lower
+     or upper bound of the range, whichever is closer to the specified
+     position.
+
+   GB_NO_ERROR_IF_BAD
+
+     If the position is outside the allowable range, return -1.
+
+   GB_NEGATIVE_FROM_END
+
+     If a value is negative, treat it as an offset from the end.
+     Only applies to strings.
+
+   The following additional flags apply only to the functions
+   that return ranges:
+
+   GB_ALLOW_NIL
+
+     Either or both positions can be nil.  If FROM is nil,
+     FROM_OUT will contain the lower bound of the allowed range.
+     If TO is nil, TO_OUT will contain the upper bound of the
+     allowed range.
+
+   GB_CHECK_ORDER
+
+     FROM must contain the lower bound and TO the upper bound
+     of the range.  If the positions are reversed, an error is
+     signalled.
+
+   The following is a combination flag:
+
+   GB_HISTORICAL_STRING_BEHAVIOR
+
+     Equivalent to (GB_NEGATIVE_FROM_END | GB_ALLOW_NIL).
+ */
+
+/* Return a buffer position stored in a Lisp_Object.  Full
+   error-checking is done on the position.  Flags can be specified to
+   control the behavior of out-of-range values.  The default behavior
+   is to require that the position is within the accessible part of
+   the buffer (BEGV and ZV), and to signal an error if the position is
+   out of range.
+
+*/
+
+Bufpos
+get_buffer_pos_char (struct buffer *b, Lisp_Object pos, unsigned int flags)
+{
+  Bufpos ind;
+  Bufpos min_allowed, max_allowed;
+
+  CHECK_INT_COERCE_MARKER (pos);
+  ind = XINT (pos);
+  min_allowed = flags & GB_ALLOW_PAST_ACCESSIBLE ? BUF_BEG (b) : BUF_BEGV (b);
+  max_allowed = flags & GB_ALLOW_PAST_ACCESSIBLE ? BUF_Z   (b) : BUF_ZV   (b);
+
+  if (ind < min_allowed || ind > max_allowed)
+    {
+      if (flags & GB_COERCE_RANGE)
+	ind = ind < min_allowed ? min_allowed : max_allowed;
+      else if (flags & GB_NO_ERROR_IF_BAD)
+	ind = -1;
+      else
+	{
+	  Lisp_Object buffer;
+	  XSETBUFFER (buffer, b);
+	  args_out_of_range (buffer, pos);
+	}
+    }
+
+  return ind;
+}
+
+Bytind
+get_buffer_pos_byte (struct buffer *b, Lisp_Object pos, unsigned int flags)
+{
+  Bufpos bpos = get_buffer_pos_char (b, pos, flags);
+  if (bpos < 0) /* could happen with GB_NO_ERROR_IF_BAD */
+    return -1;
+  return bufpos_to_bytind (b, bpos);
+}
+
+/* Return a pair of buffer positions representing a range of text,
+   taken from a pair of Lisp_Objects.  Full error-checking is
+   done on the positions.  Flags can be specified to control the
+   behavior of out-of-range values.  The default behavior is to
+   allow the range bounds to be specified in either order
+   (however, FROM_OUT will always be the lower bound of the range
+   and TO_OUT the upper bound),to require that the positions
+   are within the accessible part of the buffer (BEGV and ZV),
+   and to signal an error if the positions are out of range.
+*/
+
+void
+get_buffer_range_char (struct buffer *b, Lisp_Object from, Lisp_Object to,
+		       Bufpos *from_out, Bufpos *to_out, unsigned int flags)
+{
+  Bufpos min_allowed, max_allowed;
+
+  min_allowed = (flags & GB_ALLOW_PAST_ACCESSIBLE) ?
+    BUF_BEG (b) : BUF_BEGV (b);
+  max_allowed = (flags & GB_ALLOW_PAST_ACCESSIBLE) ?
+    BUF_Z (b) : BUF_ZV (b);
+
+  if (NILP (from) && (flags & GB_ALLOW_NIL))
+    *from_out = min_allowed;
+  else
+    *from_out = get_buffer_pos_char (b, from, flags | GB_NO_ERROR_IF_BAD);
+
+  if (NILP (to) && (flags & GB_ALLOW_NIL))
+    *to_out = max_allowed;
+  else
+    *to_out = get_buffer_pos_char (b, to, flags | GB_NO_ERROR_IF_BAD);
+
+  if ((*from_out < 0 || *to_out < 0) && !(flags & GB_NO_ERROR_IF_BAD))
+    {
+      Lisp_Object buffer;
+      XSETBUFFER (buffer, b);
+      args_out_of_range_3 (buffer, from, to);
+    }
+
+  if (*from_out >= 0 && *to_out >= 0 && *from_out > *to_out)
+    {
+      if (flags & GB_CHECK_ORDER)
+	signal_simple_error_2 ("start greater than end", from, to);
+      else
+	{
+	  Bufpos temp = *from_out;
+	  *from_out = *to_out;
+	  *to_out = temp;
+	}
+    }
+}
+
+void
+get_buffer_range_byte (struct buffer *b, Lisp_Object from, Lisp_Object to,
+		       Bytind *from_out, Bytind *to_out, unsigned int flags)
+{
+  Bufpos s, e;
+
+  get_buffer_range_char (b, from, to, &s, &e, flags);
+  if (s >= 0)
+    *from_out = bufpos_to_bytind (b, s);
+  else /* could happen with GB_NO_ERROR_IF_BAD */
+    *from_out = -1;
+  if (e >= 0)
+    *to_out = bufpos_to_bytind (b, e);
+  else
+    *to_out = -1;
+}
+
+static Charcount
+get_string_pos_char_1 (Lisp_Object string, Lisp_Object pos, unsigned int flags,
+		       Charcount known_length)
+{
+  Charcount ccpos;
+  Charcount min_allowed = 0;
+  Charcount max_allowed = known_length;
+
+  /* Computation of KNOWN_LENGTH is potentially expensive so we pass
+     it in. */
+  CHECK_INT (pos);
+  ccpos = XINT (pos);
+  if (ccpos < 0 && flags & GB_NEGATIVE_FROM_END)
+    ccpos += max_allowed;
+
+  if (ccpos < min_allowed || ccpos > max_allowed)
+    {
+      if (flags & GB_COERCE_RANGE)
+	ccpos = ccpos < min_allowed ? min_allowed : max_allowed;
+      else if (flags & GB_NO_ERROR_IF_BAD)
+	ccpos = -1;
+      else
+	args_out_of_range (string, pos);
+    }
+
+  return ccpos;
+}
+
+Charcount
+get_string_pos_char (Lisp_Object string, Lisp_Object pos, unsigned int flags)
+{
+  return get_string_pos_char_1 (string, pos, flags,
+				XSTRING_CHAR_LENGTH (string));
+}
+
+Bytecount
+get_string_pos_byte (Lisp_Object string, Lisp_Object pos, unsigned int flags)
+{
+  Charcount ccpos = get_string_pos_char (string, pos, flags);
+  if (ccpos < 0) /* could happen with GB_NO_ERROR_IF_BAD */
+    return -1;
+  return charcount_to_bytecount (XSTRING_DATA (string), ccpos);
+}
+
+void
+get_string_range_char (Lisp_Object string, Lisp_Object from, Lisp_Object to,
+		       Charcount *from_out, Charcount *to_out,
+		       unsigned int flags)
+{
+  Charcount min_allowed = 0;
+  Charcount max_allowed = XSTRING_CHAR_LENGTH (string);
+
+  if (NILP (from) && (flags & GB_ALLOW_NIL))
+    *from_out = min_allowed;
+  else
+    *from_out = get_string_pos_char_1 (string, from,
+				       flags | GB_NO_ERROR_IF_BAD,
+				       max_allowed);
+
+  if (NILP (to) && (flags & GB_ALLOW_NIL))
+    *to_out = max_allowed;
+  else
+    *to_out = get_string_pos_char_1 (string, to,
+				     flags | GB_NO_ERROR_IF_BAD,
+				     max_allowed);
+
+  if ((*from_out < 0 || *to_out < 0) && !(flags & GB_NO_ERROR_IF_BAD))
+    args_out_of_range_3 (string, from, to);
+
+  if (*from_out >= 0 && *to_out >= 0 && *from_out > *to_out)
+    {
+      if (flags & GB_CHECK_ORDER)
+	signal_simple_error_2 ("start greater than end", from, to);
+      else
+	{
+	  Bufpos temp = *from_out;
+	  *from_out = *to_out;
+	  *to_out = temp;
+	}
+    }
+}
+
+void
+get_string_range_byte (Lisp_Object string, Lisp_Object from, Lisp_Object to,
+		       Bytecount *from_out, Bytecount *to_out,
+		       unsigned int flags)
+{
+  Charcount s, e;
+
+  get_string_range_char (string, from, to, &s, &e, flags);
+  if (s >= 0)
+    *from_out = charcount_to_bytecount (XSTRING_DATA (string), s);
+  else /* could happen with GB_NO_ERROR_IF_BAD */
+    *from_out = -1;
+  if (e >= 0)
+    *to_out = charcount_to_bytecount (XSTRING_DATA (string), e);
+  else
+    *to_out = -1;
+
+}
+
+Bufpos
+get_buffer_or_string_pos_char (Lisp_Object object, Lisp_Object pos,
+			       unsigned int flags)
+{
+  return STRINGP (object) ?
+    get_string_pos_char (object, pos, flags) :
+    get_buffer_pos_char (XBUFFER (object), pos, flags);
+}
+
+Bytind
+get_buffer_or_string_pos_byte (Lisp_Object object, Lisp_Object pos,
+			       unsigned int flags)
+{
+  return STRINGP (object) ?
+    get_string_pos_byte (object, pos, flags) :
+    get_buffer_pos_byte (XBUFFER (object), pos, flags);
+}
+
+void
+get_buffer_or_string_range_char (Lisp_Object object, Lisp_Object from,
+				 Lisp_Object to, Bufpos *from_out,
+				 Bufpos *to_out, unsigned int flags)
+{
+  if (STRINGP (object))
+    get_string_range_char (object, from, to, from_out, to_out, flags);
+  else
+    get_buffer_range_char (XBUFFER (object), from, to, from_out, to_out, flags);
+}
+
+void
+get_buffer_or_string_range_byte (Lisp_Object object, Lisp_Object from,
+				 Lisp_Object to, Bytind *from_out,
+				 Bytind *to_out, unsigned int flags)
+{
+  if (STRINGP (object))
+    get_string_range_byte (object, from, to, from_out, to_out, flags);
+  else
+    get_buffer_range_byte (XBUFFER (object), from, to, from_out, to_out, flags);
+}
+
+Bufpos
+buffer_or_string_accessible_begin_char (Lisp_Object object)
+{
+  return STRINGP (object) ? 0 : BUF_BEGV (XBUFFER (object));
+}
+
+Bufpos
+buffer_or_string_accessible_end_char (Lisp_Object object)
+{
+  return STRINGP (object) ?
+    XSTRING_CHAR_LENGTH (object) : BUF_ZV (XBUFFER (object));
+}
+
+Bytind
+buffer_or_string_accessible_begin_byte (Lisp_Object object)
+{
+  return STRINGP (object) ? 0 : BI_BUF_BEGV (XBUFFER (object));
+}
+
+Bytind
+buffer_or_string_accessible_end_byte (Lisp_Object object)
+{
+  return STRINGP (object) ?
+    XSTRING_LENGTH (object) : BI_BUF_ZV (XBUFFER (object));
+}
+
+Bufpos
+buffer_or_string_absolute_begin_char (Lisp_Object object)
+{
+  return STRINGP (object) ? 0 : BUF_BEG (XBUFFER (object));
+}
+
+Bufpos
+buffer_or_string_absolute_end_char (Lisp_Object object)
+{
+  return STRINGP (object) ?
+    XSTRING_CHAR_LENGTH (object) : BUF_Z (XBUFFER (object));
+}
+
+Bytind
+buffer_or_string_absolute_begin_byte (Lisp_Object object)
+{
+  return STRINGP (object) ? 0 : BI_BUF_BEG (XBUFFER (object));
+}
+
+Bytind
+buffer_or_string_absolute_end_byte (Lisp_Object object)
+{
+  return STRINGP (object) ?
+    XSTRING_LENGTH (object) : BI_BUF_Z (XBUFFER (object));
+}
+
+
+/************************************************************************/
+/*                     point and marker adjustment                      */
+/************************************************************************/
+
+/* just_set_point() is the only place `PT' is an lvalue in all of emacs.
+   This function is called from set_buffer_point(), which is the function
+   that the SET_PT and BUF_SET_PT macros expand into, and from the
+   routines below that insert and delete text. (This is in cases where
+   the point marker logically doesn't move but PT (being a byte index)
+   needs to get adjusted.) */
+
+/* Set point to a specified value.  This is used only when the value
+   of point changes due to an insert or delete; it does not represent
+   a conceptual change in point as a marker.  In particular, point is
+   not crossing any interval boundaries, so there's no need to use the
+   usual SET_PT macro.  In fact it would be incorrect to do so, because
+   either the old or the new value of point is out of synch with the
+   current set of intervals.  */
+
+/* This gets called more than enough to make the function call
+   overhead a significant factor so we've turned it into a macro. */
+#define JUST_SET_POINT(buf, bufpos, ind)	\
+do						\
+{						\
+  buf->bufpt = (bufpos);			\
+  buf->pt = (ind);				\
+} while (0)
+
+/* Set a buffer's point. */
+
+void
+set_buffer_point (struct buffer *buf, Bufpos bufpos, Bytind bytpos)
+{
+  assert (bytpos >= BI_BUF_BEGV (buf) && bytpos <= BI_BUF_ZV (buf));
+  if (bytpos == BI_BUF_PT (buf))
+    return;
+  JUST_SET_POINT (buf, bufpos, bytpos);
+  MARK_POINT_CHANGED;
+  assert (MARKERP (buf->point_marker));
+  XMARKER (buf->point_marker)->memind =
+    bytind_to_memind (buf, bytpos);
+
+  /* FSF makes sure that PT is not being set within invisible text.
+     However, this is the wrong place for that check.  The check
+     should happen only at the next redisplay. */
+
+  /* Some old coder said:
+
+     "If there were to be hooks which were run when point entered/left an
+     extent, this would be the place to put them.
+
+     However, it's probably the case that such hooks should be implemented
+     using a post-command-hook instead, to avoid running the hooks as a
+     result of intermediate motion inside of save-excursions, for example."
+
+     I definitely agree with this.  PT gets moved all over the place
+     and it would be a Bad Thing for any hooks to get called, both for
+     the reason above and because many callers are not prepared for
+     a GC within this function. --ben
+   */
+}
+
+/* Do the correct marker-like adjustment on MPOS (see below).  FROM, TO,
+   and AMOUNT are as in adjust_markers().  If MPOS doesn't need to be
+   adjusted, nothing will happen. */
+Memind
+do_marker_adjustment (Memind mpos, Memind from,
+		      Memind to, Bytecount amount)
+{
+  if (amount > 0)
+    {
+      if (mpos > to && mpos < to + amount)
+	mpos = to + amount;
+    }
+  else
+    {
+      if (mpos > from + amount && mpos <= from)
+	mpos = from + amount;
+    }
+  if (mpos > from && mpos <= to)
+    mpos += amount;
+  return mpos;
+}
+
+/* Do the following:
+
+   (1) Add `amount' to the position of every marker in the current buffer
+   whose current position is between `from' (exclusive) and `to' (inclusive).
+
+   (2) Also, any markers past the outside of that interval, in the direction
+   of adjustment, are first moved back to the near end of the interval
+   and then adjusted by `amount'.
+
+   This function is called in two different cases: when a region of
+   characters adjacent to the gap is moved, causing the gap to shift
+   to the other side of the region (in this case, `from' and `to'
+   point to the old position of the region and there should be no
+   markers affected by (2) because they would be inside the gap),
+   or when a region of characters adjacent to the gap is wiped out,
+   causing the gap to increase to include the region (in this case,
+   `from' and `to' are the same, both pointing to the boundary
+   between the gap and the deleted region, and there are no markers
+   affected by (1)).
+
+   The reason for the use of exclusive and inclusive is that markers at
+   the gap always sit at the beginning, not at the end.
+*/
+
+static void
+adjust_markers (struct buffer *buf, Memind from, Memind to,
+		Bytecount amount)
+{
+  struct Lisp_Marker *m;
+
+  for (m = BUF_MARKERS (buf); m; m = marker_next (m))
+    m->memind = do_marker_adjustment (m->memind, from, to, amount);
+}
+
+/* Adjust markers whose insertion-type is t
+   for an insertion of AMOUNT characters at POS.  */
+
+static void
+adjust_markers_for_insert (struct buffer *buf, Memind ind, Bytecount amount)
+{
+  struct Lisp_Marker *m;
+
+  for (m = BUF_MARKERS (buf); m; m = marker_next (m))
+    {
+      if (m->insertion_type && m->memind == ind)
+	m->memind += amount;
+    }
+}
+
+
+/************************************************************************/
+/*                  Routines for dealing with the gap                   */
+/************************************************************************/
+
+/* XEmacs requires an ANSI C compiler, and it damn well better have a
+   working memmove() */
+#define GAP_USE_BCOPY
+#ifdef BCOPY_UPWARD_SAFE
+# undef BCOPY_UPWARD_SAFE
+#endif
+#ifdef BCOPY_DOWNWARD_SAFE
+# undef BCOPY_DOWNWARD_SAFE
+#endif
+#define BCOPY_UPWARD_SAFE 1
+#define BCOPY_DOWNWARD_SAFE 1
+
+/* maximum amount of memory moved in a single chunk.  Increasing this
+   value improves gap-motion efficiency but decreases QUIT responsiveness
+   time.  Was 32000 but today's processors are faster and files are
+   bigger.  --ben */
+#define GAP_MOVE_CHUNK 300000
+
+/* Move the gap to POS, which is less than the current GPT. */
+
+static void
+gap_left (struct buffer *buf, Bytind pos)
+{
+  Bufbyte *to, *from;
+  Bytecount i;
+  Bytind new_s1;
+  struct buffer *mbuf;
+  Lisp_Object bufcons;
+
+  from = BUF_GPT_ADDR (buf);
+  to = from + BUF_GAP_SIZE (buf);
+  new_s1 = BI_BUF_GPT (buf);
+
+  /* Now copy the characters.  To move the gap down,
+     copy characters up.  */
+
+  while (1)
+    {
+      /* I gets number of characters left to copy.  */
+      i = new_s1 - pos;
+      if (i == 0)
+	break;
+      /* If a quit is requested, stop copying now.
+	 Change POS to be where we have actually moved the gap to.  */
+      if (QUITP)
+	{
+	  pos = new_s1;
+	  break;
+	}
+      /* Move at most GAP_MOVE_CHUNK chars before checking again for a quit. */
+      if (i > GAP_MOVE_CHUNK)
+	i = GAP_MOVE_CHUNK;
+#ifdef GAP_USE_BCOPY
+      if (i >= 128
+	  /* bcopy is safe if the two areas of memory do not overlap
+	     or on systems where bcopy is always safe for moving upward.  */
+	  && (BCOPY_UPWARD_SAFE
+	      || to - from >= 128))
+	{
+	  /* If overlap is not safe, avoid it by not moving too many
+	     characters at once.  */
+	  if (!BCOPY_UPWARD_SAFE && i > to - from)
+	    i = to - from;
+	  new_s1 -= i;
+	  from -= i, to -= i;
+	  memmove (to, from, i);
+	}
+      else
+#endif
+	{
+	  new_s1 -= i;
+	  while (--i >= 0)
+	    *--to = *--from;
+	}
+    }
+
+  /* Adjust markers, and buffer data structure, to put the gap at POS.
+     POS is where the loop above stopped, which may be what was specified
+     or may be where a quit was detected.  */
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      adjust_markers (mbuf, pos, BI_BUF_GPT (mbuf), BUF_GAP_SIZE (mbuf));
+    }
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      adjust_extents (make_buffer (mbuf), pos, BI_BUF_GPT (mbuf),
+		      BUF_GAP_SIZE (mbuf));
+    }
+  SET_BI_BUF_GPT (buf, pos);
+  SET_GAP_SENTINEL (buf);
+#ifdef ERROR_CHECK_EXTENTS
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      sledgehammer_extent_check (make_buffer (mbuf));
+    }
+#endif
+  QUIT;
+}
+
+static void
+gap_right (struct buffer *buf, Bytind pos)
+{
+  Bufbyte *to, *from;
+  Bytecount i;
+  Bytind new_s1;
+  struct buffer *mbuf;
+  Lisp_Object bufcons;
+
+  to = BUF_GPT_ADDR (buf);
+  from = to + BUF_GAP_SIZE (buf);
+  new_s1 = BI_BUF_GPT (buf);
+
+  /* Now copy the characters.  To move the gap up,
+     copy characters down.  */
+
+  while (1)
+    {
+      /* I gets number of characters left to copy.  */
+      i = pos - new_s1;
+      if (i == 0)
+	break;
+      /* If a quit is requested, stop copying now.
+	 Change POS to be where we have actually moved the gap to.  */
+      if (QUITP)
+	{
+	  pos = new_s1;
+	  break;
+	}
+      /* Move at most GAP_MOVE_CHUNK chars before checking again for a quit. */
+      if (i > GAP_MOVE_CHUNK)
+	i = GAP_MOVE_CHUNK;
+#ifdef GAP_USE_BCOPY
+      if (i >= 128
+	  /* bcopy is safe if the two areas of memory do not overlap
+	     or on systems where bcopy is always safe for moving downward. */
+	  && (BCOPY_DOWNWARD_SAFE
+	      || from - to >= 128))
+	{
+	  /* If overlap is not safe, avoid it by not moving too many
+	     characters at once.  */
+	  if (!BCOPY_DOWNWARD_SAFE && i > from - to)
+	    i = from - to;
+	  new_s1 += i;
+	  memmove (to, from, i);
+	  from += i, to += i;
+	}
+      else
+#endif
+	{
+	  new_s1 += i;
+	  while (--i >= 0)
+	    *to++ = *from++;
+	}
+    }
+
+  {
+    int gsize = BUF_GAP_SIZE (buf);
+    MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+      {
+	adjust_markers (mbuf, BI_BUF_GPT (mbuf) + gsize, pos + gsize, - gsize);
+      }
+    MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+      {
+	adjust_extents (make_buffer (mbuf), BI_BUF_GPT (mbuf) + gsize,
+			pos + gsize, - gsize);
+      }
+    SET_BI_BUF_GPT (buf, pos);
+    SET_GAP_SENTINEL (buf);
+#ifdef ERROR_CHECK_EXTENTS
+    MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+      {
+	sledgehammer_extent_check (make_buffer (mbuf));
+      }
+#endif
+  }
+  if (pos == BI_BUF_Z (buf))
+    {
+      /* merge gap with end gap */
+
+      SET_BUF_GAP_SIZE (buf, BUF_GAP_SIZE (buf) + BUF_END_GAP_SIZE (buf));
+      SET_BUF_END_GAP_SIZE (buf, 0);
+      SET_END_SENTINEL (buf);
+    }
+
+  QUIT;
+}
+
+/* Move gap to position `pos'.
+   Note that this can quit!  */
+
+static void
+move_gap (struct buffer *buf, Bytind pos)
+{
+  if (! BUF_BEG_ADDR (buf))
+    abort ();
+  if (pos < BI_BUF_GPT (buf))
+    gap_left (buf, pos);
+  else if (pos > BI_BUF_GPT (buf))
+    gap_right (buf, pos);
+}
+
+/* Merge the end gap into the gap */
+
+static void
+merge_gap_with_end_gap (struct buffer *buf)
+{
+  Lisp_Object tem;
+  Bytind real_gap_loc;
+  Bytecount old_gap_size;
+  Bytecount increment;
+
+  increment = BUF_END_GAP_SIZE (buf);
+  SET_BUF_END_GAP_SIZE (buf, 0);
+
+  if (increment > 0)
+    {
+      /* Prevent quitting in move_gap.  */
+      tem = Vinhibit_quit;
+      Vinhibit_quit = Qt;
+
+      real_gap_loc = BI_BUF_GPT (buf);
+      old_gap_size = BUF_GAP_SIZE (buf);
+
+      /* Pretend the end gap is the gap */
+      SET_BI_BUF_GPT (buf, BI_BUF_Z (buf) + BUF_GAP_SIZE (buf));
+      SET_BUF_GAP_SIZE (buf, increment);
+
+      /* Move the new gap down to be consecutive with the end of the old one.
+	 This adjusts the markers properly too.  */
+      gap_left (buf, real_gap_loc + old_gap_size);
+
+      /* Now combine the two into one large gap.  */
+      SET_BUF_GAP_SIZE (buf, BUF_GAP_SIZE (buf) + old_gap_size);
+      SET_BI_BUF_GPT (buf, real_gap_loc);
+      SET_GAP_SENTINEL (buf);
+
+      /* We changed the total size of the buffer (including gap),
+	 so we need to fix up the end sentinel. */
+      SET_END_SENTINEL (buf);
+
+      Vinhibit_quit = tem;
+    }
+}
+
+/* Make the gap INCREMENT bytes longer.  */
+
+static void
+make_gap (struct buffer *buf, Bytecount increment)
+{
+  Bufbyte *result;
+  Lisp_Object tem;
+  Bytind real_gap_loc;
+  Bytecount old_gap_size;
+
+  /* If we have to get more space, get enough to last a while.  We use
+     a geometric progression that saves on realloc space. */
+  increment += 2000 + ((BI_BUF_Z (buf) - BI_BUF_BEG (buf)) / 8);
+
+  if (increment > BUF_END_GAP_SIZE (buf))
+    {
+      /* Don't allow a buffer size that won't fit in an int
+	 even if it will fit in a Lisp integer.
+	 That won't work because so many places use `int'.  */
+
+      if (BUF_Z (buf) - BUF_BEG (buf) + BUF_GAP_SIZE (buf) + increment
+	  > EMACS_INT_MAX)
+	error ("Maximum buffer size exceeded");
+
+      result = BUFFER_REALLOC (buf->text->beg,
+			       BI_BUF_Z (buf) - BI_BUF_BEG (buf) +
+			       BUF_GAP_SIZE (buf) + increment +
+			       BUF_END_SENTINEL_SIZE);
+      if (result == 0)
+	memory_full ();
+
+      SET_BUF_BEG_ADDR (buf, result);
+    }
+  else
+    increment = BUF_END_GAP_SIZE (buf);
+
+  /* Prevent quitting in move_gap.  */
+  tem = Vinhibit_quit;
+  Vinhibit_quit = Qt;
+
+  real_gap_loc = BI_BUF_GPT (buf);
+  old_gap_size = BUF_GAP_SIZE (buf);
+
+  /* Call the newly allocated space a gap at the end of the whole space.  */
+  SET_BI_BUF_GPT (buf, BI_BUF_Z (buf) + BUF_GAP_SIZE (buf));
+  SET_BUF_GAP_SIZE (buf, increment);
+
+  SET_BUF_END_GAP_SIZE (buf, 0);
+
+  /* Move the new gap down to be consecutive with the end of the old one.
+     This adjusts the markers properly too.  */
+  gap_left (buf, real_gap_loc + old_gap_size);
+
+  /* Now combine the two into one large gap.  */
+  SET_BUF_GAP_SIZE (buf, BUF_GAP_SIZE (buf) + old_gap_size);
+  SET_BI_BUF_GPT (buf, real_gap_loc);
+  SET_GAP_SENTINEL (buf);
+
+  /* We changed the total size of the buffer (including gap),
+     so we need to fix up the end sentinel. */
+  SET_END_SENTINEL (buf);
+
+  Vinhibit_quit = tem;
+}
+
+
+/************************************************************************/
+/*                     Before/after-change processing                   */
+/************************************************************************/
+
+/* Those magic changes ... */
+
+static void
+buffer_signal_changed_region (struct buffer *buf, Bufpos start,
+			      Bufpos end)
+{
+  /* The changed region is recorded as the number of unchanged
+     characters from the beginning and from the end of the
+     buffer.  This obviates much of the need of shifting the
+     region around to compensate for insertions and deletions.
+     */
+  if (buf->changes->begin_unchanged < 0 ||
+      buf->changes->begin_unchanged > start - BUF_BEG (buf))
+    buf->changes->begin_unchanged = start - BUF_BEG (buf);
+  if (buf->changes->end_unchanged < 0 ||
+      buf->changes->end_unchanged > BUF_Z (buf) - end)
+    buf->changes->end_unchanged = BUF_Z (buf) - end;
+}
+
+void
+buffer_extent_signal_changed_region (struct buffer *buf, Bufpos start,
+				     Bufpos end)
+{
+  if (buf->changes->begin_extent_unchanged < 0 ||
+      buf->changes->begin_extent_unchanged > start - BUF_BEG (buf))
+    buf->changes->begin_extent_unchanged = start - BUF_BEG (buf);
+  if (buf->changes->end_extent_unchanged < 0 ||
+      buf->changes->end_extent_unchanged > BUF_Z (buf) - end)
+    buf->changes->end_extent_unchanged = BUF_Z (buf) - end;
+}
+
+void
+buffer_reset_changes (struct buffer *buf)
+{
+  buf->changes->begin_unchanged = -1;
+  buf->changes->end_unchanged = -1;
+  buf->changes->begin_extent_unchanged = -1;
+  buf->changes->end_extent_unchanged = -1;
+  buf->changes->newline_was_deleted = 0;
+}
+
+static void
+signal_after_change (struct buffer *buf, Bufpos start, Bufpos orig_end,
+		     Bufpos new_end);
+
+
+/* Call the after-change-functions according to the changes made so far
+   and treat all further changes as single until the outermost
+   multiple change exits.  This is called when the outermost multiple
+   change exits and when someone is trying to make a change that violates
+   the constraints specified in begin_multiple_change(), typically
+   when nested multiple-change sessions occur. (There are smarter ways of
+   dealing with nested multiple changes, but these rarely occur so there's
+   probably no point in it.) */
+
+/* #### This needs to keep track of what actually changed and only
+   call the after-change functions on that region. */
+
+static void
+cancel_multiple_change (struct buffer *buf)
+{
+  /* This function can GC */
+  /* Call the after-change-functions except when they've already been
+     called or when there were no changes made to the buffer at all. */
+  if (buf->text->changes->mc_begin != 0 &&
+      buf->text->changes->mc_begin_signaled)
+    {
+      Bufpos real_mc_begin = buf->text->changes->mc_begin;
+      buf->text->changes->mc_begin = 0;
+
+      signal_after_change (buf, real_mc_begin, buf->text->changes->mc_orig_end,
+			   buf->text->changes->mc_new_end);
+    }
+  else
+    {
+      buf->text->changes->mc_begin = 0;
+    }
+}
+
+/* this is an unwind_protect, to ensure that the after-change-functions
+   get called even in a non-local exit. */
+
+static Lisp_Object
+multiple_change_finish_up (Lisp_Object buffer)
+{
+  struct buffer *buf = XBUFFER (buffer);
+
+  /* #### I don't know whether or not it should even be possible to
+     get here with a dead buffer (though given how it is called I can
+     see how it might be).  In any case, there isn't time before 19.14
+     to find out. */
+  if (!BUFFER_LIVE_P (buf))
+    return Qnil;
+
+  /* This function can GC */
+  buf->text->changes->in_multiple_change = 0; /* do this first so that
+						 errors in the after-change
+						 functions don't mess things
+						 up. */
+  cancel_multiple_change (buf);
+  return Qnil;
+}
+
+/* Call this function when you're about to make a number of buffer changes
+   that should be considered a single change. (e.g. `replace-match' calls
+   this.) You need to specify the START and END of the region that is
+   going to be changed so that the before-change-functions are called
+   with the correct arguments.  The after-change region is calculated
+   automatically, however, and if changes somehow or other happen outside
+   of the specified region, that will also be handled correctly.
+
+   begin_multiple_change() returns a number (actually a specpdl depth)
+   that you must pass to end_multiple_change() when you are done. */
+
+int
+begin_multiple_change (struct buffer *buf, Bufpos start, Bufpos end)
+{
+  /* This function can GC */
+  int count = -1;
+  if (buf->text->changes->in_multiple_change)
+    {
+      if (buf->text->changes->mc_begin != 0 &&
+	  (start < buf->text->changes->mc_begin ||
+	   end > buf->text->changes->mc_new_end))
+	cancel_multiple_change (buf);
+    }
+  else
+    {
+      Lisp_Object buffer;
+
+      buf->text->changes->mc_begin = start;
+      buf->text->changes->mc_orig_end = buf->text->changes->mc_new_end = end;
+      buf->text->changes->mc_begin_signaled = 0;
+      count = specpdl_depth ();
+      XSETBUFFER (buffer, buf);
+      record_unwind_protect (multiple_change_finish_up, buffer);
+    }
+  buf->text->changes->in_multiple_change++;
+  /* We don't call before-change-functions until signal_before_change()
+     is called, in case there is a read-only or other error. */
+  return count;
+}
+
+void
+end_multiple_change (struct buffer *buf, int count)
+{
+  assert (buf->text->changes->in_multiple_change > 0);
+  buf->text->changes->in_multiple_change--;
+  if (!buf->text->changes->in_multiple_change)
+    unbind_to (count, Qnil);
+}
+
+static int inside_change_hook;
+
+static Lisp_Object
+change_function_restore (Lisp_Object buffer)
+{
+  /* We should first reset the variable and then change the buffer,
+     because Fset_buffer() can throw.  */
+  inside_change_hook = 0;
+  Fset_buffer (buffer);
+  return Qnil;
+}
+
+static int in_first_change;
+
+static Lisp_Object
+first_change_hook_restore (Lisp_Object buffer)
+{
+  in_first_change = 0;
+  Fset_buffer (buffer);
+  return Qnil;
+}
+
+/* Signal an initial modification to the buffer.  */
+
+static void
+signal_first_change (struct buffer *buf)
+{
+  /* This function can GC */
+  Lisp_Object buffer;
+  XSETBUFFER (buffer, current_buffer);
+
+  if (!in_first_change)
+    {
+      if (!NILP (symbol_value_in_buffer (Qfirst_change_hook, buffer)))
+	{
+	  int speccount = specpdl_depth ();
+	  record_unwind_protect (first_change_hook_restore, buffer);
+	  set_buffer_internal (buf);
+	  in_first_change = 1;
+	  run_hook (Qfirst_change_hook);
+	  unbind_to (speccount, Qnil);
+	}
+    }
+}
+
+/* Signal a change to the buffer immediately before it happens.
+   START and END are the bounds of the text to be changed. */
+
+static void
+signal_before_change (struct buffer *buf, Bufpos start, Bufpos end)
+{
+  /* This function can GC */
+  struct buffer *mbuf;
+  Lisp_Object bufcons;
+
+  if (!inside_change_hook)
+    {
+      Lisp_Object buffer;
+
+      /* Are we in a multiple-change session? */
+      if (buf->text->changes->in_multiple_change &&
+	  buf->text->changes->mc_begin != 0)
+	{
+	  /* If we're violating the constraints of the session,
+	     call the after-change-functions as necessary for the
+	     changes already made and treat further changes as
+	     single. */
+	  if (start < buf->text->changes->mc_begin ||
+	      end > buf->text->changes->mc_new_end)
+	    cancel_multiple_change (buf);
+	  /* Do nothing if this is not the first change in the session. */
+	  else if (buf->text->changes->mc_begin_signaled)
+	    return;
+	  else
+	    {
+	      /* First time through; call the before-change-functions
+		 specifying the entire region to be changed. (Note that
+		 we didn't call before-change-functions in
+		 begin_multiple_change() because the buffer might be
+		 read-only, etc.) */
+	      start = buf->text->changes->mc_begin;
+	      end = buf->text->changes->mc_new_end;
+	    }
+	}
+
+      /* If buffer is unmodified, run a special hook for that case.  */
+      if (BUF_SAVE_MODIFF (buf) >= BUF_MODIFF (buf))
+	{
+	  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	    {
+	      signal_first_change (mbuf);
+	    }
+	}
+
+      /* Now in any case run the before-change-functions if any.  */
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  XSETBUFFER (buffer, mbuf);
+	  if (!NILP (symbol_value_in_buffer (Qbefore_change_functions, buffer))
+	      /* Obsolete, for compatibility */
+	      || !NILP (symbol_value_in_buffer (Qbefore_change_function, buffer)))
+	    {
+	      int speccount = specpdl_depth ();
+	      record_unwind_protect (change_function_restore, Fcurrent_buffer ());
+	      set_buffer_internal (buf);
+	      inside_change_hook = 1;
+	      va_run_hook_with_args (Qbefore_change_functions, 2,
+				     make_int (start), make_int (end));
+	      /* Obsolete, for compatibility */
+	      va_run_hook_with_args (Qbefore_change_function, 2,
+				     make_int (start), make_int (end));
+	      unbind_to (speccount, Qnil);
+	    }
+	}
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  XSETBUFFER (buffer, mbuf);
+	  report_extent_modification (buffer, start, end,
+				      &inside_change_hook, 0);
+	}
+
+      /* Only now do we indicate that the before-change-functions have
+	 been called, in case some function throws out. */
+      buf->text->changes->mc_begin_signaled = 1;
+    }
+}
+
+/* Signal a change immediately after it happens.
+   START is the bufpos of the start of the changed text.
+   ORIG_END is the bufpos of the end of the before-changed text.
+   NEW_END is the bufpos of the end of the after-changed text.
+ */
+
+static void
+signal_after_change (struct buffer *buf, Bufpos start, Bufpos orig_end,
+		     Bufpos new_end)
+{
+  /* This function can GC */
+  struct buffer *mbuf;
+  Lisp_Object bufcons;
+
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      /* always do this. */
+      buffer_signal_changed_region (mbuf, start, new_end);
+    }
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      /* #### This seems inefficient.  Wouldn't it be better to just
+         keep one cache per base buffer?  */
+      font_lock_maybe_update_syntactic_caches (mbuf, start, orig_end, new_end);
+    }
+
+  if (!inside_change_hook)
+    {
+      Lisp_Object buffer;
+
+      if (buf->text->changes->in_multiple_change &&
+	  buf->text->changes->mc_begin != 0)
+	{
+	  assert (start >= buf->text->changes->mc_begin &&
+		  start <= buf->text->changes->mc_new_end);
+	  assert (orig_end >= buf->text->changes->mc_begin &&
+		  orig_end <= buf->text->changes->mc_new_end);
+	  buf->text->changes->mc_new_end += new_end - orig_end;
+	  return; /* after-change-functions signalled when all changes done */
+	}
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  XSETBUFFER (buffer, mbuf);
+
+	  if (!NILP (symbol_value_in_buffer (Qafter_change_functions, buffer))
+	      /* Obsolete, for compatibility */
+	      || !NILP (symbol_value_in_buffer (Qafter_change_function, buffer)))
+	    {
+	      int speccount = specpdl_depth ();
+	      record_unwind_protect (change_function_restore, Fcurrent_buffer ());
+	      set_buffer_internal (buf);
+	      inside_change_hook = 1;
+	      /* The actual after-change functions take slightly
+		 different arguments than what we were passed. */
+	      va_run_hook_with_args (Qafter_change_functions, 3,
+				     make_int (start), make_int (new_end),
+				     make_int (orig_end - start));
+	      /* Obsolete, for compatibility */
+	      va_run_hook_with_args (Qafter_change_function, 3,
+				     make_int (start), make_int (new_end),
+				     make_int (orig_end - start));
+	      unbind_to (speccount, Qnil);
+	    }
+	}
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  XSETBUFFER (buffer, mbuf);
+	  report_extent_modification (buffer, start, new_end,
+				      &inside_change_hook, 1);
+	}
+    }
+}
+
+/* Call this if you're about to change the region of BUFFER from START
+   to END.  This checks the read-only properties of the region, calls
+   the necessary modification hooks, and warns the next redisplay that
+   it should pay attention to that area.  */
+
+static void
+prepare_to_modify_buffer (struct buffer *buf, Bufpos start, Bufpos end,
+			  int lockit)
+{
+  /* This function can GC */
+  /* dmoore - This function can also kill the buffer buf, the current
+     buffer, and do anything it pleases.  So if you call it, be
+     careful. */
+  struct buffer *mbuf;
+  Lisp_Object buffer, bufcons;
+  struct gcpro gcpro1;
+
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      barf_if_buffer_read_only (mbuf, start, end);
+    }
+
+  /* if this is the first modification, see about locking the buffer's
+     file */
+  XSETBUFFER (buffer, buf);
+  GCPRO1 (buffer);
+  if (!NILP (buf->filename) && lockit &&
+      BUF_SAVE_MODIFF (buf) >= BUF_MODIFF (buf))
+    {
+#ifdef CLASH_DETECTION
+      if (!NILP (buf->file_truename))
+	/* Make binding buffer-file-name to nil effective.  */
+	lock_file (buf->file_truename);
+#else
+      /* At least warn if this file has changed on disk since it was visited.*/
+      if (NILP (Fverify_visited_file_modtime (buffer))
+	  && !NILP (Ffile_exists_p (buf->filename)))
+	call1_in_buffer (buf, intern ("ask-user-about-supersession-threat"),
+			 buf->filename);
+#endif /* not CLASH_DETECTION */
+    }
+  UNGCPRO;
+
+  /* #### dmoore - is this reasonable in case of buf being killed above? */
+  if (!BUFFER_LIVE_P (buf))
+    return;
+
+  signal_before_change (buf, start, end);
+
+#ifdef REGION_CACHE_NEEDS_WORK
+  if (buf->newline_cache)
+    invalidate_region_cache (buf,
+                             buf->newline_cache,
+                             start - BUF_BEG (buf), BUF_Z (buf) - end);
+  if (buf->width_run_cache)
+    invalidate_region_cache (buf,
+                             buf->width_run_cache,
+                             start - BUF_BEG (buf), BUF_Z (buf) - end);
+#endif
+
+#if 0 /* FSFmacs */
+  Vdeactivate_mark = Qt;
+#endif
+
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      mbuf->point_before_scroll = Qnil;
+    }
+}
+
+
+/************************************************************************/
+/*                        Insertion of strings                          */
+/************************************************************************/
+
+void
+fixup_internal_substring (CONST Bufbyte *nonreloc, Lisp_Object reloc,
+			  Bytecount offset, Bytecount *len)
+{
+  assert ((nonreloc && NILP (reloc)) || (!nonreloc && STRINGP (reloc)));
+
+  if (*len < 0)
+    {
+      if (nonreloc)
+	*len = strlen ((CONST char *) nonreloc) - offset;
+      else
+	*len = XSTRING_LENGTH (reloc) - offset;
+    }
+#ifdef ERROR_CHECK_BUFPOS
+  assert (*len >= 0);
+  if (STRINGP (reloc))
+    {
+      assert (offset >= 0 && offset <= XSTRING_LENGTH (reloc));
+      assert (offset + *len <= XSTRING_LENGTH (reloc));
+    }
+#endif
+}
+
+/* Insert a string into BUF at Bufpos POS.  The string data comes
+   from one of two sources: constant, non-relocatable data (specified
+   in NONRELOC), or a Lisp string object (specified in RELOC), which
+   is relocatable and may have extent data that needs to be copied
+   into the buffer.  OFFSET and LENGTH specify the substring of the
+   data that is actually to be inserted.  As a special case, if POS
+   is -1, insert the string at point and move point to the end of the
+   string.
+
+   Normally, markers at the insertion point end up before the
+   inserted string.  If INSDEL_BEFORE_MARKERS is set in flags, however,
+   they end up after the string.
+
+   INSDEL_NO_LOCKING is kludgy and is used when insert-file-contents is
+   visiting a new file; it inhibits the locking checks normally done
+   before modifying a buffer.  Similar checks were already done
+   in the higher-level Lisp functions calling insert-file-contents. */
+
+Charcount
+buffer_insert_string_1 (struct buffer *buf, Bufpos pos,
+			CONST Bufbyte *nonreloc, Lisp_Object reloc,
+			Bytecount offset, Bytecount length,
+			int flags)
+{
+  /* This function can GC */
+  struct gcpro gcpro1;
+  Bytind ind;
+  Charcount cclen;
+  int move_point = 0;
+  struct buffer *mbuf;
+  Lisp_Object bufcons;
+
+  /* Defensive steps just in case a buffer gets deleted and a calling
+     function doesn't notice it. */
+  if (!BUFFER_LIVE_P (buf))
+    return 0;
+
+  fixup_internal_substring (nonreloc, reloc, offset, &length);
+
+  if (pos == -1)
+    {
+      pos = BUF_PT (buf);
+      move_point = 1;
+    }
+
+#ifdef I18N3
+  /* #### See the comment in print_internal().  If this buffer is marked
+     as translatable, then Fgettext() should be called on obj if it
+     is a string. */
+#endif
+
+  /* Make sure that point-max won't exceed the size of an emacs int. */
+  if ((length + BUF_Z (buf)) > EMACS_INT_MAX)
+    error ("Maximum buffer size exceeded");
+
+  /* theoretically not necessary -- caller should GCPRO.
+     #### buffer_insert_from_buffer_1() doesn't!  */
+  GCPRO1 (reloc);
+
+  prepare_to_modify_buffer (buf, pos, pos, !(flags & INSDEL_NO_LOCKING));
+
+  /* Defensive steps in case the before-change-functions fuck around */
+  if (!BUFFER_LIVE_P (buf))
+    {
+      UNGCPRO;
+      /* Bad bad pre-change function. */
+      return 0;
+    }
+
+  /* Make args be valid again.  prepare_to_modify_buffer() might have
+     modified the buffer. */
+  if (pos < BUF_BEGV (buf))
+    pos = BUF_BEGV (buf);
+  if (pos > BUF_ZV (buf))
+    pos = BUF_ZV (buf);
+
+  /* string may have been relocated up to this point */
+  if (STRINGP (reloc))
+    nonreloc = XSTRING_DATA (reloc);
+
+  ind = bufpos_to_bytind (buf, pos);
+  cclen = bytecount_to_charcount (nonreloc + offset, length);
+
+  if (ind != BI_BUF_GPT (buf))
+    /* #### if debug-on-quit is invoked and the user changes the
+       buffer, bad things can happen.  This is a rampant problem
+       in Emacs. */
+    move_gap (buf, ind); /* may QUIT */
+  if (! GAP_CAN_HOLD_SIZE_P (buf, length))
+    {
+      if (BUF_END_GAP_SIZE (buf) >= length)
+	merge_gap_with_end_gap (buf);
+      else
+	make_gap (buf, length - BUF_GAP_SIZE (buf));
+    }
+
+  insert_invalidate_line_number_cache (buf, pos, nonreloc + offset, length);
+
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      record_insert (mbuf, pos, cclen);
+    }
+
+  BUF_MODIFF (buf)++;
+  MARK_BUFFERS_CHANGED;
+
+  /* string may have been relocated up to this point */
+  if (STRINGP (reloc))
+    nonreloc = XSTRING_DATA (reloc);
+
+  memcpy (BUF_GPT_ADDR (buf), nonreloc + offset, length);
+
+  SET_BUF_GAP_SIZE (buf, BUF_GAP_SIZE (buf) - length);
+  SET_BI_BUF_GPT (buf, BI_BUF_GPT (buf) + length);
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      SET_BOTH_BUF_ZV (mbuf, BUF_ZV (mbuf) + cclen, BI_BUF_ZV (mbuf) + length);
+    }
+  SET_BOTH_BUF_Z (buf, BUF_Z (buf) + cclen, BI_BUF_Z (buf) + length);
+  SET_GAP_SENTINEL (buf);
+
+#ifdef MULE
+  buffer_mule_signal_inserted_region (buf, pos, length, cclen);
+#endif
+
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      process_extents_for_insertion (make_buffer (mbuf), ind, length);
+    }
+
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      /* We know the gap is at IND so the cast is OK. */
+      adjust_markers_for_insert (mbuf, (Memind) ind, length);
+    }
+
+  /* Point logically doesn't move, but may need to be adjusted because
+     it's a byte index.  point-marker doesn't change because it's a
+     memory index. */
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      if (BI_BUF_PT (mbuf) > ind)
+	JUST_SET_POINT (mbuf, BUF_PT (mbuf) + cclen,
+			BI_BUF_PT (mbuf) + length);
+    }
+
+  /* Well, point might move. */
+  if (move_point)
+    BI_BUF_SET_PT (buf, ind + length);
+
+  if (STRINGP (reloc))
+    {
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  splice_in_string_extents (reloc, mbuf, ind, length, offset);
+	}
+    }
+
+  if (flags & INSDEL_BEFORE_MARKERS)
+    {
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  /* ind - 1 is correct because the FROM argument is exclusive.
+	     I formerly used DEC_BYTIND() but that caused problems at the
+	     beginning of the buffer. */
+	  adjust_markers (mbuf, ind - 1, ind, length);
+	}
+    }
+
+  signal_after_change (buf, pos, pos, pos + cclen);
+
+  UNGCPRO;
+
+  return cclen;
+}
+
+
+/* The following functions are interfaces onto the above function,
+   for inserting particular sorts of data.  In all the functions,
+   BUF and POS specify the buffer and location where the insertion is
+   to take place. (If POS is -1, text is inserted at point and point
+   moves forward past the text.) FLAGS is as above. */
+
+Charcount
+buffer_insert_raw_string_1 (struct buffer *buf, Bufpos pos,
+			    CONST Bufbyte *nonreloc, Bytecount length,
+			    int flags)
+{
+  /* This function can GC */
+  return buffer_insert_string_1 (buf, pos, nonreloc, Qnil, 0, length,
+				 flags);
+}
+
+Charcount
+buffer_insert_lisp_string_1 (struct buffer *buf, Bufpos pos, Lisp_Object str,
+			     int flags)
+{
+  /* This function can GC */
+#ifdef ERROR_CHECK_TYPECHECK
+  assert (STRINGP (str));
+#endif
+  return buffer_insert_string_1 (buf, pos, 0, str, 0,
+				 XSTRING_LENGTH (str),
+				 flags);
+}
+
+/* Insert the null-terminated string S (in external format). */
+
+Charcount
+buffer_insert_c_string_1 (struct buffer *buf, Bufpos pos, CONST char *s,
+			  int flags)
+{
+  /* This function can GC */
+  CONST char *translated = GETTEXT (s);
+  return buffer_insert_string_1 (buf, pos, (CONST Bufbyte *) translated, Qnil,
+				 0, strlen (translated), flags);
+}
+
+Charcount
+buffer_insert_emacs_char_1 (struct buffer *buf, Bufpos pos, Emchar ch,
+			    int flags)
+{
+  /* This function can GC */
+  Bufbyte str[MAX_EMCHAR_LEN];
+  Bytecount len = set_charptr_emchar (str, ch);
+  return buffer_insert_string_1 (buf, pos, str, Qnil, 0, len, flags);
+}
+
+Charcount
+buffer_insert_c_char_1 (struct buffer *buf, Bufpos pos, char c,
+			int flags)
+{
+  /* This function can GC */
+  return buffer_insert_emacs_char_1 (buf, pos, (Emchar) (unsigned char) c,
+				     flags);
+}
+
+Charcount
+buffer_insert_from_buffer_1 (struct buffer *buf, Bufpos pos,
+			     struct buffer *buf2, Bufpos pos2,
+			     Charcount length, int flags)
+{
+  /* This function can GC */
+  Lisp_Object str = make_string_from_buffer (buf2, pos2, length);
+  return buffer_insert_string_1 (buf, pos, 0, str, 0,
+				 XSTRING_LENGTH (str), flags);
+}
+
+
+/************************************************************************/
+/*                        Deletion of ranges                            */
+/************************************************************************/
+
+/* Delete characters in buffer from FROM up to (but not including) TO.  */
+
+void
+buffer_delete_range (struct buffer *buf, Bufpos from, Bufpos to, int flags)
+{
+  /* This function can GC */
+  Charcount numdel;
+  Bytind bi_from, bi_to;
+  Bytecount bc_numdel;
+  EMACS_INT shortage;
+  struct buffer *mbuf;
+  Lisp_Object bufcons;
+
+  /* Defensive steps just in case a buffer gets deleted and a calling
+     function doesn't notice it. */
+  if (!BUFFER_LIVE_P (buf))
+    return;
+
+  /* Make args be valid */
+  if (from < BUF_BEGV (buf))
+    from = BUF_BEGV (buf);
+  if (to > BUF_ZV (buf))
+    to = BUF_ZV (buf);
+  if ((numdel = to - from) <= 0)
+    return;
+
+  prepare_to_modify_buffer (buf, from, to, !(flags & INSDEL_NO_LOCKING));
+
+  /* Defensive steps in case the before-change-functions fuck around */
+  if (!BUFFER_LIVE_P (buf))
+    /* Bad bad pre-change function. */
+    return;
+
+  /* Make args be valid again.  prepare_to_modify_buffer() might have
+     modified the buffer. */
+  if (from < BUF_BEGV (buf))
+    from = BUF_BEGV (buf);
+  if (to > BUF_ZV (buf))
+    to = BUF_ZV (buf);
+  if ((numdel = to - from) <= 0)
+    return;
+
+  /* Redisplay needs to know if a newline was in the deleted region.
+     If we've already marked the changed region as having a deleted
+     newline there is no use in performing the check. */
+  if (!buf->changes->newline_was_deleted)
+    {
+      scan_buffer (buf, '\n', from, to, 1, &shortage, 1);
+      if (!shortage)
+	{
+	  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	    {
+	      mbuf->changes->newline_was_deleted = 1;
+	    }
+	}
+    }
+
+  bi_from = bufpos_to_bytind (buf, from);
+  bi_to = bufpos_to_bytind (buf, to);
+  bc_numdel = bi_to - bi_from;
+
+  delete_invalidate_line_number_cache (buf, from, to);
+
+  if (to == BUF_Z (buf) &&
+      bi_from > BI_BUF_GPT (buf))
+    {
+      /* avoid moving the gap just to delete from the bottom. */
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  record_delete (mbuf, from, numdel);
+	}
+      BUF_MODIFF (buf)++;
+      MARK_BUFFERS_CHANGED;
+
+      /* #### Point used to be modified here, but this causes problems
+	 with MULE, as point is used to calculate bytinds, and if the
+	 offset in bc_numdel causes point to move to a non first-byte
+	 location, causing some other function to throw an assertion
+	 in ASSERT_VALID_BYTIND. I've moved the code to right after
+	 the other movements and adjustments, but before the gap is
+	 moved.  -- jh 970813 */
+
+      /* Detach any extents that are completely within the range [FROM, TO],
+	 if the extents are detachable.
+
+	 This must come AFTER record_delete(), so that the appropriate
+	 extents will be present to be recorded, and BEFORE the gap
+	 size is increased, as otherwise we will be confused about
+	 where the extents end. */
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  process_extents_for_deletion (make_buffer (mbuf), bi_from, bi_to, 0);
+	}
+
+      /* Relocate all markers pointing into the new, larger gap to
+	 point at the end of the text before the gap.  */
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  adjust_markers (mbuf,
+			  (bi_to + BUF_GAP_SIZE (mbuf)),
+			  (bi_to + BUF_GAP_SIZE (mbuf)),
+			  (- bc_numdel));
+	}
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  /* Relocate any extent endpoints just like markers. */
+	  adjust_extents_for_deletion (make_buffer (mbuf), bi_from, bi_to,
+				       BUF_GAP_SIZE (mbuf), bc_numdel, 0);
+	}
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  /* Relocate point as if it were a marker.  */
+	  if (bi_from < BI_BUF_PT (mbuf))
+	    {
+	      if (BI_BUF_PT (mbuf) < bi_to)
+		JUST_SET_POINT (mbuf, from, bi_from);
+	      else
+		JUST_SET_POINT (mbuf, BUF_PT (mbuf) - numdel,
+				BI_BUF_PT (mbuf) - bc_numdel);
+	    }
+	}
+
+      SET_BUF_END_GAP_SIZE (buf, BUF_END_GAP_SIZE (buf) + bc_numdel);
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  SET_BOTH_BUF_ZV (mbuf, BUF_ZV (mbuf) - numdel,
+			   BI_BUF_ZV (mbuf) - bc_numdel);
+	}
+      SET_BOTH_BUF_Z (buf, BUF_Z (buf) - numdel, BI_BUF_Z (buf) - bc_numdel);
+      SET_GAP_SENTINEL (buf);
+    }
+  else
+    {
+      /* Make sure the gap is somewhere in or next to what we are deleting.  */
+      if (bi_to < BI_BUF_GPT (buf))
+	gap_left (buf, bi_to);
+      if (bi_from > BI_BUF_GPT (buf))
+	gap_right (buf, bi_from);
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  record_delete (mbuf, from, numdel);
+	}
+      BUF_MODIFF (buf)++;
+      MARK_BUFFERS_CHANGED;
+
+      /* #### Point used to be modified here, but this causes problems
+	 with MULE, as point is used to calculate bytinds, and if the
+	 offset in bc_numdel causes point to move to a non first-byte
+	 location, causing some other function to throw an assertion
+	 in ASSERT_VALID_BYTIND. I've moved the code to right after
+	 the other movements and adjustments, but before the gap is
+	 moved.  -- jh 970813 */
+
+      /* Detach any extents that are completely within the range [FROM, TO],
+	 if the extents are detachable.
+
+	 This must come AFTER record_delete(), so that the appropriate extents
+	 will be present to be recorded, and BEFORE the gap size is increased,
+	 as otherwise we will be confused about where the extents end. */
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  process_extents_for_deletion (make_buffer (mbuf), bi_from, bi_to, 0);
+	}
+
+      /* Relocate all markers pointing into the new, larger gap to
+	 point at the end of the text before the gap.  */
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  adjust_markers (mbuf,
+			  (bi_to + BUF_GAP_SIZE (mbuf)),
+			  (bi_to + BUF_GAP_SIZE (mbuf)),
+			  (- bc_numdel - BUF_GAP_SIZE (mbuf)));
+	}
+
+      /* Relocate any extent endpoints just like markers. */
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  adjust_extents_for_deletion (make_buffer (mbuf), bi_from, bi_to,
+				       BUF_GAP_SIZE (mbuf),
+				       bc_numdel, BUF_GAP_SIZE (mbuf));
+	}
+
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  /* Relocate point as if it were a marker.  */
+	  if (bi_from < BI_BUF_PT (mbuf))
+	    {
+	      if (BI_BUF_PT (mbuf) < bi_to)
+		JUST_SET_POINT (mbuf, from, bi_from);
+	      else
+		JUST_SET_POINT (mbuf, BUF_PT (mbuf) - numdel,
+				BI_BUF_PT (mbuf) - bc_numdel);
+	    }
+	}
+
+      SET_BUF_GAP_SIZE (buf, BUF_GAP_SIZE (buf) + bc_numdel);
+      MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	{
+	  SET_BOTH_BUF_ZV (mbuf, BUF_ZV (mbuf) - numdel,
+			   BI_BUF_ZV (mbuf) - bc_numdel);
+	}
+      SET_BOTH_BUF_Z (buf, BUF_Z (buf) - numdel, BI_BUF_Z (buf) - bc_numdel);
+      SET_BI_BUF_GPT (buf, bi_from);
+      SET_GAP_SENTINEL (buf);
+    }
+
+#ifdef MULE
+  buffer_mule_signal_deleted_region (buf, from, to, bi_from, bi_to);
+#endif
+
+#ifdef ERROR_CHECK_EXTENTS
+  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+    {
+      sledgehammer_extent_check (make_buffer (mbuf));
+    }
+#endif
+
+  signal_after_change (buf, from, to, from);
+}
+
+
+/************************************************************************/
+/*                    Replacement of characters                         */
+/************************************************************************/
+
+/* Replace the character at POS in buffer B with CH. */
+
+void
+buffer_replace_char (struct buffer *buf, Bufpos pos, Emchar ch,
+		     int not_real_change, int force_lock_check)
+{
+  /* This function can GC */
+  Bufbyte curstr[MAX_EMCHAR_LEN];
+  Bufbyte newstr[MAX_EMCHAR_LEN];
+  Bytecount curlen, newlen;
+
+  /* Defensive steps just in case a buffer gets deleted and a calling
+     function doesn't notice it. */
+  if (!BUFFER_LIVE_P (buf))
+    return;
+
+  curlen = BUF_CHARPTR_COPY_CHAR (buf, pos, curstr);
+  newlen = set_charptr_emchar (newstr, ch);
+
+  if (curlen == newlen)
+    {
+      struct buffer *mbuf;
+      Lisp_Object bufcons;
+
+      /* then we can just replace the text. */
+      prepare_to_modify_buffer (buf, pos, pos + 1,
+				!not_real_change || force_lock_check);
+      /* Defensive steps in case the before-change-functions fuck around */
+      if (!BUFFER_LIVE_P (buf))
+	/* Bad bad pre-change function. */
+	return;
+
+      /* Make args be valid again.  prepare_to_modify_buffer() might have
+	 modified the buffer. */
+      if (pos < BUF_BEGV (buf))
+	pos = BUF_BEGV (buf);
+      if (pos >= BUF_ZV (buf))
+	pos = BUF_ZV (buf) - 1;
+      if (pos < BUF_BEGV (buf))
+	/* no more characters in buffer! */
+	return;
+
+      if (BUF_FETCH_CHAR (buf, pos) == '\n')
+	{
+	  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	    {
+	      mbuf->changes->newline_was_deleted = 1;
+	    }
+	}
+      MARK_BUFFERS_CHANGED;
+      if (!not_real_change)
+	{
+	  MAP_INDIRECT_BUFFERS (buf, mbuf, bufcons)
+	    {
+	      record_change (mbuf, pos, 1);
+	    }
+	  BUF_MODIFF (buf)++;
+	}
+      memcpy (BUF_BYTE_ADDRESS (buf, pos), newstr, newlen);
+
+      signal_after_change (buf, pos, pos + 1, pos + 1);
+
+      /* We do not have to adjust the Mule data; we just replaced a
+	 character with another of the same number of bytes. */
+    }
+  else
+    {
+      /*
+       * Must implement as deletion followed by insertion.
+       *
+       * Make a note to move point forward later in the one situation
+       * where it is needed, a delete/insert one position behind
+       * point.  Point will drift backward by one position and stay
+       * there otherwise.
+       */
+      int movepoint = (pos == BUF_PT (buf) - 1);
+
+      buffer_delete_range (buf, pos, pos + 1, 0);
+      /* Defensive steps in case the before-change-functions fuck around */
+      if (!BUFFER_LIVE_P (buf))
+	/* Bad bad pre-change function. */
+	return;
+
+      /* Make args be valid again.  prepare_to_modify_buffer() might have
+	 modified the buffer. */
+      if (pos < BUF_BEGV (buf))
+	pos = BUF_BEGV (buf);
+      if (pos >= BUF_ZV (buf))
+	pos = BUF_ZV (buf) - 1;
+      if (pos < BUF_BEGV (buf))
+	/* no more characters in buffer! */
+	return;
+      /*
+       * -1 as the pos argument means to move point forward with the
+       * insertion, which we must do if the deletion moved point
+       * backward so that it now equals the insertion point.
+       */
+      buffer_insert_string_1 (buf, (movepoint ? -1 : pos),
+			      newstr, Qnil, 0, newlen, 0);
+    }
+}
+
+
+/************************************************************************/
+/*                            Other functions                           */
+/************************************************************************/
+
+/* Make a string from a buffer.  This needs to take into account the gap,
+   and add any necessary extents from the buffer. */
+
+static Lisp_Object
+make_string_from_buffer_1 (struct buffer *buf, Bufpos pos, Charcount length,
+			   int no_extents)
+{
+  /* This function can GC */
+  Bytind    bi_ind = bufpos_to_bytind (buf, pos);
+  Bytecount bi_len = bufpos_to_bytind (buf, pos + length) - bi_ind;
+  Lisp_Object  val = make_uninit_string (bi_len);
+
+  struct gcpro gcpro1;
+  GCPRO1 (val);
+
+  if (!no_extents)
+    add_string_extents (val, buf, bi_ind, bi_len);
+
+  {
+    Bytecount len1 = BI_BUF_GPT (buf) - bi_ind;
+    Bufbyte *start1 = BI_BUF_BYTE_ADDRESS (buf, bi_ind);
+    Bufbyte *dest = XSTRING_DATA (val);
+
+    if (len1 < 0)
+      {
+	/* Completely after gap */
+	memcpy (dest, start1, bi_len);
+      }
+    else if (bi_len <= len1)
+      {
+	/* Completely before gap */
+	memcpy (dest, start1, bi_len);
+      }
+    else
+      {
+	/* Spans gap */
+	Bytind pos2 = bi_ind + len1;
+	Bufbyte *start2 = BI_BUF_BYTE_ADDRESS (buf, pos2);
+
+	memcpy (dest, start1, len1);
+	memcpy (dest + len1, start2, bi_len - len1);
+      }
+  }
+
+  UNGCPRO;
+  return val;
+}
+
+Lisp_Object
+make_string_from_buffer (struct buffer *buf, Bufpos pos, Charcount length)
+{
+  return make_string_from_buffer_1 (buf, pos, length, 0);
+}
+
+Lisp_Object
+make_string_from_buffer_no_extents (struct buffer *buf, Bufpos pos,
+				    Charcount length)
+{
+  return make_string_from_buffer_1 (buf, pos, length, 1);
+}
+
+void
+barf_if_buffer_read_only (struct buffer *buf, Bufpos from, Bufpos to)
+{
+  Lisp_Object buffer;
+  Lisp_Object iro;
+
+  XSETBUFFER (buffer, buf);
+ back:
+  iro = (buf == current_buffer ? Vinhibit_read_only :
+	 symbol_value_in_buffer (Qinhibit_read_only, buffer));
+  if (!LISTP (iro))
+    return;
+  if (NILP (iro) && !NILP (buf->read_only))
+    {
+      Fsignal (Qbuffer_read_only, (list1 (buffer)));
+      goto back;
+    }
+  if (from > 0)
+    {
+      if (to < 0)
+	to = from;
+      verify_extent_modification (buffer,
+				  bufpos_to_bytind (buf, from),
+				  bufpos_to_bytind (buf, to),
+				  iro);
+    }
+}
+
+void
+find_charsets_in_bufbyte_string (unsigned char *charsets, CONST Bufbyte *str,
+				 Bytecount len)
+{
+#ifndef MULE
+  /* Telescope this. */
+  charsets[0] = 1;
+#else
+  CONST Bufbyte *strend = str + len;
+  memset (charsets, 0, NUM_LEADING_BYTES);
+
+  while (str < strend)
+    {
+      charsets[CHAR_LEADING_BYTE (charptr_emchar (str)) - 128] = 1;
+      INC_CHARPTR (str);
+    }
+#endif
+}
+
+void
+find_charsets_in_emchar_string (unsigned char *charsets, CONST Emchar *str,
+				Charcount len)
+{
+#ifndef MULE
+  /* Telescope this. */
+  charsets[0] = 1;
+#else
+  int i;
+
+  memset (charsets, 0, NUM_LEADING_BYTES);
+  for (i = 0; i < len; i++)
+    {
+      charsets[CHAR_LEADING_BYTE (str[i]) - 128] = 1;
+    }
+#endif
+}
+
+int
+bufbyte_string_displayed_columns (CONST Bufbyte *str, Bytecount len)
+{
+  int cols = 0;
+  CONST Bufbyte *end = str + len;
+
+  while (str < end)
+    {
+#ifdef MULE
+      Emchar ch = charptr_emchar (str);
+      cols += XCHARSET_COLUMNS (CHAR_CHARSET (ch));
+#else
+      cols++;
+#endif
+      INC_CHARPTR (str);
+    }
+
+  return cols;
+}
+
+int
+emchar_string_displayed_columns (CONST Emchar *str, Charcount len)
+{
+#ifdef MULE
+  int cols = 0;
+  int i;
+
+  for (i = 0; i < len; i++)
+    cols += XCHARSET_COLUMNS (CHAR_CHARSET (str[i]));
+
+  return cols;
+#else  /* not MULE */
+  return len;
+#endif
+}
+
+/* NOTE: Does not reset the Dynarr. */
+
+void
+convert_bufbyte_string_into_emchar_dynarr (CONST Bufbyte *str, Bytecount len,
+					   Emchar_dynarr *dyn)
+{
+  CONST Bufbyte *strend = str + len;
+
+  while (str < strend)
+    {
+      Emchar ch = charptr_emchar (str);
+      Dynarr_add (dyn, ch);
+      INC_CHARPTR (str);
+    }
+}
+
+Charcount
+convert_bufbyte_string_into_emchar_string (CONST Bufbyte *str, Bytecount len,
+					   Emchar *arr)
+{
+  CONST Bufbyte *strend = str + len;
+  Charcount newlen = 0;
+  while (str < strend)
+    {
+      Emchar ch = charptr_emchar (str);
+      arr[newlen++] = ch;
+      INC_CHARPTR (str);
+    }
+  return newlen;
+}
+
+/* Convert an array of Emchars into the equivalent string representation.
+   Store into the given Bufbyte dynarr.  Does not reset the dynarr.
+   Does not add a terminating zero. */
+
+void
+convert_emchar_string_into_bufbyte_dynarr (Emchar *arr, int nels,
+					  Bufbyte_dynarr *dyn)
+{
+  Bufbyte str[MAX_EMCHAR_LEN];
+  int i;
+
+  for (i = 0; i < nels; i++)
+    {
+      Bytecount len = set_charptr_emchar (str, arr[i]);
+      Dynarr_add_many (dyn, str, len);
+    }
+}
+
+/* Convert an array of Emchars into the equivalent string representation.
+   Malloc the space needed for this and return it.  If LEN_OUT is not a
+   NULL pointer, store into LEN_OUT the number of Bufbytes in the
+   malloc()ed string.  Note that the actual number of Bufbytes allocated
+   is one more than this: the returned string is zero-terminated. */
+
+Bufbyte *
+convert_emchar_string_into_malloced_string (Emchar *arr, int nels,
+					   Bytecount *len_out)
+{
+  /* Damn zero-termination. */
+  Bufbyte *str = (Bufbyte *) alloca (nels * MAX_EMCHAR_LEN + 1);
+  Bufbyte *strorig = str;
+  Bytecount len;
+
+  int i;
+
+  for (i = 0; i < nels; i++)
+    str += set_charptr_emchar (str, arr[i]);
+  *str = '\0';
+  len = str - strorig;
+  str = (Bufbyte *) xmalloc (1 + len);
+  memcpy (str, strorig, 1 + len);
+  if (len_out)
+    *len_out = len;
+  return str;
+}
+
+
+/************************************************************************/
+/*                            initialization                            */
+/************************************************************************/
+
+void
+reinit_vars_of_insdel (void)
+{
+  int i;
+
+  inside_change_hook = 0;
+  in_first_change = 0;
+
+  for (i = 0; i <= MAX_BYTIND_GAP_SIZE_3; i++)
+    three_to_one_table[i] = i / 3;
+}
+
+void
+vars_of_insdel (void)
+{
+  reinit_vars_of_insdel ();
+}
+
+void
+init_buffer_text (struct buffer *b)
+{
+  if (!b->base_buffer)
+    {
+      SET_BUF_GAP_SIZE (b, 20);
+      BUFFER_ALLOC (b->text->beg, BUF_GAP_SIZE (b) + BUF_END_SENTINEL_SIZE);
+      if (! BUF_BEG_ADDR (b))
+	memory_full ();
+
+      SET_BUF_END_GAP_SIZE (b, 0);
+      SET_BI_BUF_GPT (b, 1);
+      SET_BOTH_BUF_Z (b, 1, 1);
+      SET_GAP_SENTINEL (b);
+      SET_END_SENTINEL (b);
+#ifdef MULE
+      {
+	int i;
+
+	b->text->mule_bufmin = b->text->mule_bufmax = 1;
+	b->text->mule_bytmin = b->text->mule_bytmax = 1;
+	b->text->mule_shifter = 0;
+	b->text->mule_three_p = 0;
+
+	for (i = 0; i < 16; i++)
+	  {
+	    b->text->mule_bufpos_cache[i] = 1;
+	    b->text->mule_bytind_cache[i] = 1;
+	  }
+      }
+#endif /* MULE */
+      b->text->line_number_cache = Qnil;
+
+      BUF_MODIFF (b) = 1;
+      BUF_SAVE_MODIFF (b) = 1;
+
+      JUST_SET_POINT (b, 1, 1);
+      SET_BOTH_BUF_BEGV (b, 1, 1);
+      SET_BOTH_BUF_ZV (b, 1, 1);
+
+      b->text->changes = xnew_and_zero (struct buffer_text_change_data);
+    }
+  else
+    {
+      JUST_SET_POINT (b, BUF_PT (b->base_buffer), BI_BUF_PT (b->base_buffer));
+      SET_BOTH_BUF_BEGV (b, BUF_BEGV (b->base_buffer),
+			 BI_BUF_BEGV (b->base_buffer));
+      SET_BOTH_BUF_ZV (b, BUF_ZV (b->base_buffer),
+			 BI_BUF_ZV (b->base_buffer));
+    }
+
+  b->changes = xnew_and_zero (struct each_buffer_change_data);
+  BUF_FACECHANGE (b) = 1;
+
+#ifdef REGION_CACHE_NEEDS_WORK
+  b->newline_cache = 0;
+  b->width_run_cache = 0;
+  b->width_table = Qnil;
+#endif
+}
+
+void
+uninit_buffer_text (struct buffer *b)
+{
+  if (!b->base_buffer)
+    {
+      BUFFER_FREE (b->text->beg);
+      xfree (b->text->changes);
+    }
+  xfree (b->changes);
+
+#ifdef REGION_CACHE_NEEDS_WORK
+  if (b->newline_cache)
+    {
+      free_region_cache (b->newline_cache);
+      b->newline_cache = 0;
+    }
+  if (b->width_run_cache)
+    {
+      free_region_cache (b->width_run_cache);
+      b->width_run_cache = 0;
+    }
+  b->width_table = Qnil;
+#endif
+}