Move av_malloc(), av_realloc(), and av_free() from libavcodec to libavutil

Originally committed as revision 5784 to svn://svn.ffmpeg.org/ffmpeg/trunk
2006-07-19 07:28:58 +00:00
parent b8889ea51f
commit cea8f6f323
5 changed files with 11 additions and 8 deletions
--- a/libavutil/mem.c
+++ b/libavutil/mem.c
@ -0,0 +1,137 @@
+/*
+ * default memory allocator for libavutil
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file mem.c
+ * default memory allocator for libavutil.
+ */
+
+#include "common.h"
+
+/* here we can use OS dependant allocation functions */
+#undef malloc
+#undef free
+#undef realloc
+
+#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 allocation of size byte with alignment suitable for all
+ * memory accesses (including vectors if available on the
+ * CPU). av_malloc(0) must return a non NULL pointer.
+ */
+void *av_malloc(unsigned int size)
+{
+    void *ptr;
+#ifdef MEMALIGN_HACK
+    long diff;
+#endif
+
+    /* let's disallow possible ambiguous cases */
+    if(size > (INT_MAX-16) )
+        return NULL;
+
+#ifdef MEMALIGN_HACK
+    ptr = malloc(size+16);
+    if(!ptr)
+        return ptr;
+    diff= ((-(long)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:
+         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!
+     */
+     /* Why 16?
+        because some cpus need alignment, for example SSE2 on P4, & most RISC cpus
+        it will just trigger an exception and the unaligned load will be done in the
+        exception handler or it will just segfault (SSE2 on P4)
+        Why not larger? because i didnt see a difference in benchmarks ...
+     */
+     /* benchmarks with p3
+        memalign(64)+1          3071,3051,3032
+        memalign(64)+2          3051,3032,3041
+        memalign(64)+4          2911,2896,2915
+        memalign(64)+8          2545,2554,2550
+        memalign(64)+16         2543,2572,2563
+        memalign(64)+32         2546,2545,2571
+        memalign(64)+64         2570,2533,2558
+
+        btw, malloc seems to do 8 byte alignment by default here
+     */
+#else
+    ptr = malloc(size);
+#endif
+    return ptr;
+}
+
+/**
+ * av_realloc semantics (same as glibc): if ptr is NULL and size > 0,
+ * identical to malloc(size). If size is zero, it is identical to
+ * free(ptr) and NULL is returned.
+ */
+void *av_realloc(void *ptr, unsigned int size)
+{
+#ifdef MEMALIGN_HACK
+    int diff;
+#endif
+
+    /* let's disallow possible ambiguous cases */
+    if(size > (INT_MAX-16) )
+        return NULL;
+
+#ifdef 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;
+#else
+    return realloc(ptr, size);
+#endif
+}
+
+/**
+ * Free memory which has been allocated with av_malloc(z)() or av_realloc().
+ * NOTE: ptr = NULL is explicetly allowed
+ * Note2: it is recommended that you use av_freep() instead
+ */
+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
+}
+