dmmlib/src/split.c

/*
 *   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 "block_header.h"
#include "other.h"
#include "split.h"
#include "dmm_config.h"

void split(allocator_t *allocator, heap_t *heap, void *ptr,
        size_t req_size) {
    void *new_block;
    int fixed_list_id, i;
    size_t new_block_size;
    maptable_node_t *current_maptable_node;

    new_block = (void *) ((char *) ptr + req_size + HEADER_SIZE);
    new_block_size = get_size(ptr) - req_size - HEADER_SIZE;

    /* Resize the previous, to be used block */
    set_size_and_used(ptr, req_size);

    set_size_and_free(new_block, new_block_size);
    set_previous_size_availability(new_block, get_size_availability(ptr));

#ifdef WITH_FIXED_LISTS
    /* FIXME code from custom_free, some refactoring maybe?
     * Be careful, custom_free also does coalescing, we don't need that
     */

    /* Check if the block could be put in a fixed list */
    fixed_list_id = map_size_to_list(heap, new_block_size);

    if(fixed_list_id != -1) { /* put it in the right fixed list */
        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;
            }
        }
        push_block(&new_block, &current_maptable_node->fixed_list_head);
    } else { /* put it in the free list */
#endif /* WITH_FIXED_LISTS */
        push_block(&new_block, &heap->free_list_head);
#ifdef WITH_FIXED_LISTS
    }
#endif /* WITH_FIXED_LISTS */

#ifdef WITH_OWNERSHIP
    set_owner(new_block, heap);
#endif /* WITH_OWNERSHIP */

    if(allocator->border_ptr == ptr) {
        allocator->border_ptr = new_block;
    }

}