[Fribidi-discuss] Relocations

[Owen Taylor]

I was looking at updating the copy of fribidi in Pango to something
more recent (what's in there currently is from April of last year).

Doing this, I discovered two problems with the data structures:

 - static is missing on the arrays, so a lot of symbols are exported
   publically that don't need to be.

===
diff -u -p -r1.3 fribidi_create_char_types.c
--- fribidi_create_char_types.c	2002/01/03 15:31:24	1.3
+++ fribidi_create_char_types.c	2002/01/10 21:12:34
@@ -101,7 +101,7 @@ get_type (char *s)
 }
 
 #define table_name "FriBidiPropertyBlock"
-#define key_type_name "FriBidiPropCharType"
+#define key_type_name "static FriBidiPropCharType"
 #define macro_name "FRIBIDI_GET_TYPE"
 #define function_name "fribidi_get_type"
 #define char_type_name "FriBidiCharType"
===

   Fixes most of the problem.

 - There are a _lot_ of arrays pointing at each other. Each
   pointer to a separate symbol is a separate relocation that
   needs to be done when the library is loaded, slowing down
   loading. What's more since relocations require writing
   to the library, the data won't be shared between different
   applications using the library.

   What should be done here is to use a single array per level
   and store offsets into that. (Probably will save some memory
   as well.)

   The Unicode tables in glib were recently fixed up to work
   like this, so the files in glib-1.3.12 (say gunichartables.h)
   should provide an example of how this is done.

Regards,
                                        Owen