put memory functions in a separate file so that the user can redefinite them without modifying the library

Originally committed as revision 684 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mem.c

@@ -0,0 +1,60 @@
+/*
+ * default memory allocator for libavcodec
+ * Copyright (c) 2002 Fabrice Bellard.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include "avcodec.h"
+#ifdef HAVE_MALLOC_H
+#include <malloc.h>
+#endif
+
+/* you can redefine av_malloc and av_free in your project to use your
+   memory allocator. You do not need to suppress this file because the
+   linker will do it automatically */
+
+/* memory alloc */
+void *av_malloc(int size)
+{
+    void *ptr;
+#if defined ( ARCH_X86 ) && defined ( HAVE_MEMALIGN ) && 0
+    ptr = memalign(64,size);
+    /* Why 64? 
+       Indeed, we should align it:
+         on 4 for 386
+         on 16 for 486
+	 on 32 for 586, PPro - k6-III
+	 on 64 for K7 (maybe for P3 too).
+       Because L1 and L2 caches are aligned on those values.
+       But I don't want to code such logic here!
+     */
+#else
+    ptr = malloc(size);
+#endif
+    if (!ptr)
+        return NULL;
+    /* NOTE: this memset should not be present */
+    memset(ptr, 0, size);
+    return ptr;
+}
+
+/* NOTE: ptr = NULL is explicetly allowed */
+void av_free(void *ptr)
+{
+    /* XXX: this test should not be needed on most libcs */
+    if (ptr)
+        free(ptr);
+}
+