Re: Loading souce Elisp faster

[Richard Stallman]

This change in decode_coding_utf_8 should make it considerably faster
in the usual case where few characters need conversion.

We might still want to do something else for Elisp files,
but this is worth doing anyway since it will help for other files too.

I have not installed it myself since I have not tested it enough.

It might be worth making a similar improvement for other cases,
such as  ! multibytep && ! eol_dos  or  multibytep && eol_dos.

=== modified file 'src/coding.c'
*** src/coding.c        2013-01-25 04:41:39 +0000
--- src/coding.c        2013-02-27 11:38:18 +0000
***************
*** 1294,1299 ****
--- 1294,1338 ----
          break;
        }
  
+       /* In the simple case, rapidly handle ordinary characters */
+       if (multibytep && ! eol_dos
+         && charbuf < charbuf_end - 6 && src < src_end - 6)
+       {
+         while (charbuf < charbuf_end - 6 && src < src_end - 6)
+           {
+             c1 = *src;
+             if (c1 & 0x80)
+               break;
+             src++;
+             consumed_chars++;
+             *charbuf++ = c1;
+ 
+             c1 = *src;
+             if (c1 & 0x80)
+               break;
+             src++;
+             consumed_chars++;
+             *charbuf++ = c1;
+ 
+             c1 = *src;
+             if (c1 & 0x80)
+               break;
+             src++;
+             consumed_chars++;
+             *charbuf++ = c1;
+ 
+             c1 = *src;
+             if (c1 & 0x80)
+               break;
+             src++;
+             consumed_chars++;
+             *charbuf++ = c1;
+           }
+         /* If we handled at least one character, restart the main loop.  */
+         if (src != src_base)
+           continue;
+       }
+ 
        if (byte_after_cr >= 0)
        c1 = byte_after_cr, byte_after_cr = -1;
        else


-- 
Dr Richard Stallman
President, Free Software Foundation
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