Pass character count from coding systems to buffer insertion code. src/ChangeLog addition: 2014-01-16 Aidan Kehoe <kehoea@parhasard.net> Pass character count information from the no-conversion and unicode coding systems to the buffer insertion code, making #'find-file on large buffers a little snappier (if ERROR_CHECK_TEXT is not defined). * file-coding.c: * file-coding.c (coding_character_tell): New. * file-coding.c (conversion_coding_stream_description): New. * file-coding.c (no_conversion_convert): Update characters_seen when decoding. * file-coding.c (no_conversion_character_tell): New. * file-coding.c (lstream_type_create_file_coding): Create the no_conversion type with data. * file-coding.c (coding_system_type_create): Make the character_tell method available here. * file-coding.h: * file-coding.h (struct coding_system_methods): Add a new character_tell() method, passing charcount information from the coding systems to the buffer code, avoiding duplicate bytecount-to-charcount work especially with large buffers. * fileio.c (Finsert_file_contents_internal): Update this to pass charcount information to buffer_insert_string_1(), if that is available from the lstream code. * insdel.c: * insdel.c (buffer_insert_string_1): Add a new CCLEN argument, giving the character count of the string to insert. It can be -1 to indicate that te function should work it out itself using bytecount_to_charcount(), as it used to. * insdel.c (buffer_insert_raw_string_1): * insdel.c (buffer_insert_lisp_string_1): * insdel.c (buffer_insert_ascstring_1): * insdel.c (buffer_insert_emacs_char_1): * insdel.c (buffer_insert_from_buffer_1): * insdel.c (buffer_replace_char): Update these functions to use the new calling convention. * insdel.h: * insdel.h (buffer_insert_string): Update this header to reflect the new buffer_insert_string_1() argument. * lstream.c (Lstream_character_tell): New. Return the number of characters *read* and seen by the consumer so far, taking into account the unget buffer, and buffered reading. * lstream.c (Lstream_unread): Update unget_character_count here as appropriate. * lstream.c (Lstream_rewind): Reset unget_character_count here too. * lstream.h: * lstream.h (struct lstream): Provide the character_tell method, add a new field, unget_character_count, giving the number of characters ever passed to Lstream_unread(). Declare Lstream_character_tell(). Make Lstream_ungetc(), which happens to be unused, an inline function rather than a macro, in the course of updating it to modify unget_character_count. * print.c (output_string): Use the new argument to buffer_insert_string_1(). * tests.c: * tests.c (Ftest_character_tell): New test function. * tests.c (syms_of_tests): Make it available. * unicode.c: * unicode.c (struct unicode_coding_stream): * unicode.c (unicode_character_tell): New method. * unicode.c (unicode_convert): Update the character counter as appropriate. * unicode.c (coding_system_type_create_unicode): Make the character_tell method available.

--- a/src/fileio.c	Sun Dec 22 10:36:33 2013 +0000
+++ b/src/fileio.c	Thu Jan 16 16:27:52 2014 +0000
@@ -3180,6 +3180,7 @@
     struct gcpro ngcpro1;
     Lisp_Object stream = make_filedesc_input_stream (fd, 0, total,
 						     LSTR_ALLOW_QUIT);
+    Charcount last_tell = -1;
 
     NGCPRO1 (stream);
     Lstream_set_buffering (XLSTREAM (stream), LSTREAM_BLOCKN_BUFFERED, 65536);
@@ -3187,6 +3188,7 @@
       (XLSTREAM (stream), get_coding_system_for_text_file (codesys, 1),
        CODING_DECODE, 0);
     Lstream_set_buffering (XLSTREAM (stream), LSTREAM_BLOCKN_BUFFERED, 65536);
+    last_tell = Lstream_character_tell (XLSTREAM (stream));
 
     record_unwind_protect (delete_stream_unwind, stream);
 
@@ -3196,7 +3198,7 @@
     while (1)
       {
 	Bytecount this_len;
-	Charcount cc_inserted;
+	Charcount cc_inserted, this_tell = last_tell;
 
 	QUIT;
 	this_len = Lstream_read (XLSTREAM (stream), read_buf,
@@ -3209,12 +3211,17 @@
 	    break;
 	  }
 
-	cc_inserted = buffer_insert_raw_string_1 (buf, cur_point, read_buf,
-						  this_len,
-						  !NILP (visit)
-						  ? INSDEL_NO_LOCKING : 0);
+	cc_inserted
+          = buffer_insert_string_1 (buf, cur_point, read_buf, Qnil,
+                                    0, this_len, last_tell >= 0
+                                    ? (this_tell
+                                       = Lstream_character_tell (XLSTREAM
+                                                                 (stream)))
+                                    - last_tell : -1,
+                                    !NILP (visit) ? INSDEL_NO_LOCKING : 0);
 	inserted  += cc_inserted;
 	cur_point += cc_inserted;
+        last_tell = this_tell;
       }
     if (!NILP (used_codesys))
       {