Move *malloc() out of tree.c, that way the code can be used with

flat arrays which have lower overhead than millions of mallocd() elements.

Originally committed as revision 11399 to svn://svn.ffmpeg.org/ffmpeg/trunk

2 files changed, 16 insertions, 4 deletions

diff --git a/libavutil/tree.c b/libavutil/tree.c
index 6126ffaaa4..5c4f510db8 100644
--- a/libavutil/tree.c
+++ b/libavutil/tree.c
@@ -28,6 +28,8 @@ typedef struct AVTreeNode{
     int state;
 }AVTreeNode;
 
+const int av_tree_node_size = sizeof(AVTreeNode);
+
 void *av_tree_find(const AVTreeNode *t, void *key, int (*cmp)(void *key, const void *b), void *next[2]){
     if(t){
         unsigned int v= cmp(t->elem, key);
@@ -45,14 +47,14 @@ void *av_tree_find(const AVTreeNode *t, void *key, int (*cmp)(void *key, const v
     return NULL;
 }
 
-void *av_tree_insert(AVTreeNode **tp, void *key, int (*cmp)(void *key, const void *b)){
+void *av_tree_insert(AVTreeNode **tp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
     AVTreeNode *t= *tp;
     if(t){
         unsigned int v= cmp(t->elem, key);
         if(v){
             int i= v>>31;
             AVTreeNode **child= &t->child[i];
-            void *ret= av_tree_insert(child, key, cmp);
+            void *ret= av_tree_insert(child, key, cmp, next);
             if(!ret){
                 t->state -= ((int)v>>31)|1;
                 if(!(t->state&1)){
@@ -83,7 +85,7 @@ void *av_tree_insert(AVTreeNode **tp, void *key, int (*cmp)(void *key, const voi
             return t->elem;
         }
     }else{
-        *tp= av_mallocz(sizeof(AVTreeNode));
+        *tp= *next; *next= NULL;
         (*tp)->elem= key;
         return NULL;
     }
diff --git a/libavutil/tree.h b/libavutil/tree.h
index 146d35d56e..d801a4e028 100644
--- a/libavutil/tree.h
+++ b/libavutil/tree.h
@@ -28,6 +28,7 @@
 #define FFMPEG_TREE_H
 
 struct AVTreeNode;
+extern const int av_tree_node_size;
 
 /**
  * Finds an element.
@@ -46,13 +47,22 @@ void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *ke
  * @param rootp A pointer to a pointer to the root node of the tree. Note that
  *              the root node can change during insertions, this is required
  *              to keep the tree balanced.
+ * @param next AVTreeNode used for the inserted element, must be allocated and
+ *             zeroed by the user. And will be set to NULL if used by
+ *             av_tree_insert(). This allows the use of flat arrays, which have
+ *             lower overhead compared to many malloced elements.
+ *             You might want to define a function like:
+ *             void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
+ *                 if(!*next) *next= av_mallocz(av_tree_node_size);
+ *                 return av_tree_insert(rootp, key, cmp, next);
+ *             }
  *
  * @return If no insertion happened, the found element.
  *         If an insertion happened, then either key or NULL will be returned.
  *         Which one it is depends on the tree state and the implementation. You
  *         should make no assumptions that it's one or the other in the code.
  */
-void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b));
+void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next);
 void av_tree_destroy(struct AVTreeNode *t);
 
 #endif /* FFMPEG_TREE_H */