(advance_to_char_boundary): Don't use DEC_POS to find a

apparent char boundary.
(Fset_buffer_multibyte): Convert 8-bit characters in the range
0x80..0x9F to/from multibyte form.

diff --git a/src/buffer.c b/src/buffer.c
index 6550d6a..9587ec7 100644 (file)
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1843,8 +1843,17 @@ advance_to_char_boundary (byte_pos)
     {
       /* We should advance BYTE_POS only when C is a constituent of a
          multibyte sequence.  */
-      DEC_POS (byte_pos);
+      int orig_byte_pos = byte_pos;
+
+      do
+       {
+         byte_pos--;
+         c = FETCH_BYTE (byte_pos);
+       }
+      while (! CHAR_HEAD_P (c) && byte_pos > BEG);
       INC_POS (byte_pos);
+      if (byte_pos < orig_byte_pos)
+       byte_pos = orig_byte_pos;
       /* If C is a constituent of a multibyte sequence, BYTE_POS was
          surely advance to the correct character boundary.  If C is
          not, BYTE_POS was unchanged.  */
@@ -1865,6 +1874,9 @@ but the contents viewed as characters do change.")
 {
   Lisp_Object tail, markers;
   struct buffer *other;
+  int undo_enabled_p = !EQ (current_buffer->undo_list, Qt);
+  int begv = BEGV, zv = ZV;
+  int narrowed = (BEG != begv || Z != zv);
 
   if (current_buffer->base_buffer)
     error ("Cannot do `set-buffer-multibyte' on an indirect buffer");
@@ -1875,14 +1887,20 @@ but the contents viewed as characters do change.")
 
   /* It would be better to update the list,
      but this is good enough for now.  */
-  if (! EQ (current_buffer->undo_list, Qt))
-    current_buffer->undo_list = Qnil;
+  if (undo_enabled_p)
+    current_buffer->undo_list = Qt;
 
   /* If the cached position is for this buffer, clear it out.  */
   clear_charpos_cache (current_buffer);
 
+  if (narrowed)
+    Fwiden ();
+
   if (NILP (flag))
     {
+      int pos, stop;
+      unsigned char *p;
+
       /* Do this first, so it can use CHAR_TO_BYTE
         to calculate the old correspondences.  */
       set_intervals_multibyte (0);
@@ -1901,12 +1919,54 @@ but the contents viewed as characters do change.")
          XMARKER (tail)->charpos = XMARKER (tail)->bytepos;
          tail = XMARKER (tail)->chain;
        }
+
+      /* Convert multibyte form of 8-bit characters to unibyte.  */
+      pos = BEG;
+      stop = GPT;
+      p = BEG_ADDR;
+      while (1)
+       {
+         int c, bytes;
+
+         if (pos == stop)
+           {
+             if (pos == Z)
+               break;
+             p = GAP_END_ADDR;
+             stop = Z;
+           }
+         if (MULTIBYTE_STR_AS_UNIBYTE_P (p, bytes))
+           p += bytes, pos += bytes;
+         else
+           {
+             c = STRING_CHAR (p, stop - pos);
+             /* Delete all bytes for this 8-bit character but the
+                last one, and change the last one to the charcter
+                code.  */
+             bytes--;
+             del_range_2 (pos, pos, pos + bytes, pos + bytes, 0);
+             p = GAP_END_ADDR;
+             *p++ = c;
+             pos++;
+             if (begv > pos)
+               begv -= bytes;
+             if (zv > pos)
+               zv -= bytes;
+             stop = Z;
+           }
+       }
+      if (narrowed)
+       Fnarrow_to_region (make_number (begv), make_number (zv));
     }
   else
     {
+      int pt = PT;
+      int pos, stop;
+      unsigned char *p;
+
       /* Be sure not to have a multibyte sequence striding over the GAP.
-        Ex: We change this: "...abc\201\241\241 _GAP_ \241\241\241..."
-            to: "...abc _GAP_ \201\241\241\241\241\241..."  */
+        Ex: We change this: "...abc\201 _GAP_ \241def..."
+            to: "...abc _GAP_ \201\241def..."  */
 
       if (GPT_BYTE > 1 && GPT_BYTE < Z_BYTE
          && ! CHAR_HEAD_P (*(GAP_END_ADDR)))
@@ -1922,6 +1982,53 @@ but the contents viewed as characters do change.")
            }
        }
 
+      /* Make the buffer contents valid as multibyte by converting
+        8-bit characters to multibyte form.  */
+      pos = BEG;
+      stop = GPT;
+      p = BEG_ADDR;
+      while (1)
+       {
+         int bytes;
+
+         if (pos == stop)
+           {
+             if (pos == Z)
+               break;
+             p = GAP_END_ADDR;
+             stop = Z;
+           }
+             
+         if (UNIBYTE_STR_AS_MULTIBYTE_P (p, stop - pos, bytes))
+           p += bytes, pos += bytes;
+         else
+           {
+             unsigned char tmp[MAX_MULTIBYTE_LENGTH];
+
+             bytes = CHAR_STRING (*p, tmp);
+             *p = tmp[0];
+             TEMP_SET_PT_BOTH (pos + 1, pos + 1);
+             bytes--;
+             insert_1_both (tmp + 1, bytes, bytes, 1, 0, 0);
+             /* Now the gap is after the just inserted data.  */
+             pos = GPT;
+             p = GAP_END_ADDR;
+             if (pos <= begv)
+               begv += bytes;
+             if (pos <= zv)
+               zv += bytes;
+             if (pos <= pt)
+               pt += bytes;
+             stop = Z;
+           }
+       }
+
+      if (pt != PT)
+       TEMP_SET_PT (pt);
+
+      if (narrowed)
+       Fnarrow_to_region (make_number (begv), make_number (zv));
+
       /* Do this first, so that chars_in_text asks the right question.
         set_intervals_multibyte needs it too.  */
       current_buffer->enable_multibyte_characters = Qt;
@@ -1982,6 +2089,9 @@ but the contents viewed as characters do change.")
       set_intervals_multibyte (1);
     }
 
+  if (undo_enabled_p)
+    current_buffer->undo_list = Qnil;
+
   /* Changing the multibyteness of a buffer means that all windows
      showing that buffer must be updated thoroughly.  */
   current_buffer->prevent_redisplay_optimizations_p = 1;