[AD] Timer synchronization patch

[Eric Botcazou <ebotcazou@xxxxxxxxxx>]

The attached patch adds full-fledged synchronization to the timer code for 
multi-threaded platforms (Windows, Linux, Unix and QNX are done, BeOS not 
yet). A port has to provide 4 new methods for its system driver:

   AL_METHOD(void *, create_mutex, (void));
   AL_METHOD(void, destroy_mutex, (void *handle));
   AL_METHOD(void, lock_mutex, (void *handle));
   AL_METHOD(void, unlock_mutex, (void *handle));

and #define ALLEGRO_MULTITHREADED in order to enable the code.

The code essentially makes sure that a timer proc can't be unregistered (by 
the primary thread) while it is being executed (by the timer thread). This 
may currently happen with show_mouse(NULL): it calls

   remove_int(mouse_move);

then

  _mouse_screen = NULL;

but mouse_move() calls draw_mouse() that draws onto _mouse_screen...

Tested under DOS, Windows, Linux w/ pthreads and Linux w/o pthreads.

-- 
Eric Botcazou

Attachment: timer_sync3.zip
Description: Zip archive