/*
 *   Copyright 2011 Institute of Communication and Computer Systems (ICCS) 
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 *
 */

#include "coalesce.h"
#include "block_header.h"
#include "other.h"
#include "dmm_config.h"

void * coalesce(allocator_t *allocator, heap_t *heap, void *ptr, size_t size) {
    void *prev;
#ifdef WITH_FIXED_LISTS
    int fixed_list_id, i;
#endif /* WITH_FIXED_LISTS */
    maptable_node_t *current_maptable_node;

    prev = get_dlprevious(ptr);

#ifdef WITH_FIXED_LISTS
    // Check if it is a block of a fixed list
    fixed_list_id = map_size_to_list(heap, get_size(prev));
    if(fixed_list_id != -1) {
        // If it is, find the fixed list and remove the block
        current_maptable_node = heap->maptable_head;
        if(fixed_list_id != 0) {
            for(i = 1; i < fixed_list_id; i++) {
                current_maptable_node = current_maptable_node->next;
            }
        }
        remove_block(&ptr, &current_maptable_node->fixed_list_head);
    }
#endif /* WITH_FIXED_LISTS */

    // Set the new size
    // Note: the rest of the header variables will be set on free().
    set_size_and_free(allocator, prev, size);

    /* If the current block is the allocator's border pointer, update the
     * latter to point to the previous block.
     */
    if(allocator->border_ptr == ptr)
    {
        allocator->border_ptr = prev;
    }

    return prev;
}