[Ffmpeg-devel] [RFC] another attempt at memalign realloc

[Reimar Döffinger]

Hello,
I came up with the attached idea, but it seems so simple that I can't
get rid of the feeling there is yet another problem with that (except
that the performance might be really bad), otherwise somebody should
have had that same idea during all this wild hacking around on it *g*.
Well, please help me and have a very close look at it and say what you
think.

Greetings,
Reimar D?ffinger
-------------- next part --------------
Index: libavutil/mem.c
===================================================================
--- libavutil/mem.c	(revision 7217)
+++ libavutil/mem.c	(working copy)
@@ -105,6 +105,7 @@
 {
 #ifdef CONFIG_MEMALIGN_HACK
     int diff;
+    void *ptr2;
 #endif
 
     /* let's disallow possible ambiguous cases */
@@ -112,10 +113,17 @@
         return NULL;
 
 #ifdef CONFIG_MEMALIGN_HACK
-    //FIXME this isn't aligned correctly, though it probably isn't needed
     if(!ptr) return av_malloc(size);
     diff= ((char*)ptr)[-1];
-    return realloc(ptr - diff, size + diff) + diff;
+    ptr2 = realloc(ptr - diff, size + 16) + diff;
+    if(!((int)ptr2&15))
+        return ptr2;
+    ptr = ptr2 - diff;
+    diff= ((-(long)ptr - 1)&15) + 1;
+    ptr += diff;
+    memove(ptr, ptr2, size);
+    ((char*)ptr)[-1]= diff;
+    return ptr;
 #else
     return realloc(ptr, size);
 #endif