finally found evas_map weirdness bug. CEDRIC code...! commit #74180.

now here's the rub. from the glibc manual page:

...
       int memcmp(const void *s1, const void *s2, size_t n);

DESCRIPTION
       The  memcmp()  function compares the first n bytes (each interpreted as
       unsigned char) of the memory areas s1 and s2.  It  returns  an integer
       less than, equal to, or greater than zero if s1 is found, respectively,
       to be less than, to match, or be greater than s2.
       
RETURN VALUE
       The memcmp() function returns  an  integer  less  than, equal  to,  or
       greater than zero if the first n bytes of s1 is found, respectively, to
       be less than, to match, or be greater than the first n bytes of s2.

...

this explicitly says that s1 and s2 have their BYTES compared... and
then returns just some value < 0, 0 or > 0 based on the difference. what
that value is and means is not defined, as long as it is < 0, 0 or > 0.

so the C standard has this to say:

6.3.1.3 Signed and unsigned integers

2. Otherwise, if the new type is unsigned, the value is converted by
repeatedly adding or subtracting one more than the maximum value that
can be represented in the new type until the value is in the range of
the new type.

so a result of -255 (possible) is converted by REPEATEDLY adding the
max size of the new type (255) until within range... so ...
-255 + 255 = 0 ... within range.. BUT FALSE!

so why do we see this now? something changed in memcpy behavior.
before we ONLY saw values of -1, 0 or 1 - nothing else, NOW we see
thins like:

-12288
49152
4096
16384
61440
-53248

so memcpy changed behavior, though within specs of the manual page
anyway, but now the values can be ones that break the simple assignment.



SVN revision: 75159

legacy/evas/src/lib/canvas/evas_map.c

@@ -48,14 +48,12 @@ _evas_map_calc_map_geometry(Evas_Object *obj)
              if (obj->prev.map->count == obj->cur.map->count)
                {
                   const Evas_Map_Point *p2;
-
+                  
                   p = obj->cur.map->points;
                   p2 = obj->prev.map->points;
-
-                  ch = memcmp(p, p2,
-                              sizeof (Evas_Map_Point) * obj->prev.map->count);
-
-                  ch = !!ch;
+                  if (memcmp(p, p2, sizeof(Evas_Map_Point) * 
+                             obj->prev.map->count) != 0)
+                    ch = EINA_TRUE;
                   if (!ch)
                     {
                        if (obj->cache_map) evas_map_free(obj->cache_map);