/*
  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 #include "error.h"

 #include "log.h"

 #include "mem.h"

 #include "tree.h"
 

 typedef struct AVTreeNode {

     struct AVTreeNode *child[2];
     void *elem;
     int state;

 } AVTreeNode;

 const int av_tree_node_size = sizeof(AVTreeNode);

 
 struct AVTreeNode *av_tree_node_alloc(void)
 {
     return av_mallocz(sizeof(struct AVTreeNode));
 }

 void *av_tree_find(const AVTreeNode *t, void *key,

                    int (*cmp)(const void *key, const void *b), void *next[2])

 {
     if (t) {
         unsigned int v = cmp(key, t->elem);
         if (v) {

             if (next)
                 next[v >> 31] = t->elem;

             return av_tree_find(t->child[(v >> 31) ^ 1], key, cmp, next);
         } else {
             if (next) {

                 av_tree_find(t->child[0], key, cmp, next);
                 av_tree_find(t->child[1], key, cmp, next);
             }

             return t->elem;
         }
     }
     return NULL;
 }
 

 void *av_tree_insert(AVTreeNode **tp, void *key,

                      int (*cmp)(const void *key, const void *b), AVTreeNode **next)

 {
     AVTreeNode *t = *tp;
     if (t) {
         unsigned int v = cmp(t->elem, key);

         void *ret;

         if (!v) {
             if (*next)

                 return t->elem;

             else if (t->child[0] || t->child[1]) {
                 int i = !t->child[0];

                 void *next_elem[2];

                 av_tree_find(t->child[i], key, cmp, next_elem);

                 key = t->elem = next_elem[i];

                 v   = -i;

             } else {
                 *next = t;

                 *tp   = NULL;

                 return NULL;
             }
         }

         ret = av_tree_insert(&t->child[v >> 31], key, cmp, next);
         if (!ret) {

             int i              = (v >> 31) ^ !!*next;

             AVTreeNode **child = &t->child[i];
             t->state += 2 * i - 1;
 
             if (!(t->state & 1)) {
                 if (t->state) {

                     /* The following code is equivalent to

                      * if ((*child)->state * 2 == -t->state)
                      *     rotate(child, i ^ 1);
                      * rotate(tp, i);
                      *
                      * with rotate():
                      * static void rotate(AVTreeNode **tp, int i)
                      * {
                      *     AVTreeNode *t= *tp;
                      *
                      *     *tp = t->child[i];
                      *     t->child[i] = t->child[i]->child[i ^ 1];
                      *     (*tp)->child[i ^ 1] = t;
                      *     i = 4 * t->state + 2 * (*tp)->state + 12;
                      *     t->state     = ((0x614586 >> i) & 3) - 1;
                      *     (*tp)->state = ((0x400EEA >> i) & 3) - 1 +
                      *                    ((*tp)->state >> 1);
                      * }
                      * but such a rotate function is both bigger and slower
                      */
                     if ((*child)->state * 2 == -t->state) {

                         *tp                    = (*child)->child[i ^ 1];
                         (*child)->child[i ^ 1] = (*tp)->child[i];
                         (*tp)->child[i]        = *child;

                         *child                 = (*tp)->child[i ^ 1];

                         (*tp)->child[i ^ 1]    = t;
 
                         (*tp)->child[0]->state = -((*tp)->state > 0);

                         (*tp)->child[1]->state = (*tp)->state < 0;

                         (*tp)->state           = 0;
                     } else {

                         *tp                 = *child;
                         *child              = (*child)->child[i ^ 1];
                         (*tp)->child[i ^ 1] = t;
                         if ((*tp)->state)
                             t->state = 0;
                         else
                             t->state >>= 1;
                         (*tp)->state = -t->state;

                     }
                 }
             }

             if (!(*tp)->state ^ !!*next)

                 return key;
         }
         return ret;

     } else {
         *tp   = *next;
         *next = NULL;
         if (*tp) {
             (*tp)->elem = key;

             return NULL;

         } else

             return key;

     }
 }
 

 void av_tree_destroy(AVTreeNode *t)
 {
     if (t) {

         av_tree_destroy(t->child[0]);
         av_tree_destroy(t->child[1]);
         av_free(t);

     }

 }
 

 void av_tree_enumerate(AVTreeNode *t, void *opaque,
                        int (*cmp)(void *opaque, void *elem),
                        int (*enu)(void *opaque, void *elem))
 {
     if (t) {
         int v = cmp ? cmp(opaque, t->elem) : 0;
         if (v >= 0)
             av_tree_enumerate(t->child[0], opaque, cmp, enu);
         if (v == 0)
             enu(opaque, t->elem);
         if (v <= 0)
             av_tree_enumerate(t->child[1], opaque, cmp, enu);

     }

 }