optional and disabled by default memalign hack for SSE/SSE2 on that alternative OS

Originally committed as revision 3199 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -62,6 +62,7 @@ echo "  --disable-ffserver       disable ffserver build"
 echo "  --disable-ffplay         disable ffplay build"
 echo "  --disable-risky          disables patent encumbered codecs"
 echo "  --enable-small           optimize for size instead of speed"
+echo "  --enable-memalign-hack   emulate memalign, interferes with memory debuggers"
 echo ""
 echo "NOTE: The object files are build at the place where configure is launched"
 exit 1
@@ -178,6 +179,7 @@ amr_nb_fixed="no"
 sunmlib="no"
 pthreads="no"
 gpl="no"
+memalignhack="no"
 
 # OS specific
 targetos=`uname -s`
@@ -427,6 +429,8 @@ for opt do
   ;;
   --enable-gpl) gpl="yes"
   ;;
+  --enable-memalign-hack) memalignhack="yes"
+  ;;
   esac
 done
 
@@ -1269,6 +1273,11 @@ else
   echo "#undef  HAVE_MEMALIGN" >> $TMPH
 fi
 
+if test "$memalignhack" = "yes" ; then
+  echo "#define MEMALIGN_HACK 1" >> $TMPH
+fi
+
+
 if test "$netserver" = "yes" ; then
   echo "#define CONFIG_BEOS_NETSERVER 1" >> $TMPH
   echo "CONFIG_BEOS_NETSERVER=yes" >> config.mak

libavcodec/mem.c

@@ -46,7 +46,13 @@ void *av_malloc(unsigned int size)
 {
     void *ptr;
     
-#if defined (HAVE_MEMALIGN)
+#ifdef MEMALIGN_HACK
+    int diff;
+    ptr = malloc(size+16+1);
+    diff= ((-(int)ptr - 1)&15) + 1;
+    ptr += diff;
+    ((char*)ptr)[-1]= diff;
+#elif defined (HAVE_MEMALIGN) 
     ptr = memalign(16,size);
     /* Why 64? 
        Indeed, we should align it:
@@ -87,7 +93,13 @@ void *av_malloc(unsigned int size)
  */
 void *av_realloc(void *ptr, unsigned int size)
 {
+#ifdef MEMALIGN_HACK
+    //FIXME this isnt aligned correctly though it probably isnt needed
+    int diff= ptr ? ((char*)ptr)[-1] : 0;
+    return realloc(ptr - diff, size + diff) + diff;
+#else
     return realloc(ptr, size);
+#endif
 }
 
 /* NOTE: ptr = NULL is explicetly allowed */
@@ -95,6 +107,10 @@ void av_free(void *ptr)
 {
     /* XXX: this test should not be needed on most libcs */
     if (ptr)
+#ifdef MEMALIGN_HACK
+        free(ptr - ((char*)ptr)[-1]);
+#else
         free(ptr);
+#endif
 }