/*
 *   Copyright 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.
 *
 */

/**
 * @file   realloc.c
 * @author Ioannis Koutras (joko@microlab.ntua.gr)
 * @date   September 2012
 *
 * @brief  Implementation of realloc() call.
 */

#include "dmmlib/dmmlib.h"

#include <stdbool.h>

#ifdef BITMAP_RB_ONLY
#include "bitmap/bitmap.h"
#include "bitmap/bitmap_rb.h"
#endif /* BITMAP_RB_ONLY */

#ifdef FL_RB_ONLY
#include "freelist/freelist.h"
#include "freelist/freelist_rb.h"
#endif /* FL_RB_ONLY */

#include "release_memory.h"
#include <sys/mman.h>

#include <string.h>

#include "trace.h"

void * realloc(void *ptr, size_t size) {
    raw_block_header_t *current_raw_block;
    bool found;
    void *return_ptr;

    if(ptr == NULL) {
        return malloc(size);
    }

    if(size == 0) {
        free(ptr);
        return_ptr = malloc((size_t) 32); // FIXME 32 <- minimum size
        goto done;
    }

    current_raw_block = systemallocator.raw_block_head;
    found = false;

    while(current_raw_block) {
        if(((char *)ptr > (char *)current_raw_block) &&
                ((char *)ptr < (char *)(current_raw_block) +
                 current_raw_block->size)) {
            found = true;
            break;
        }
        current_raw_block = current_raw_block->next_raw_block;
    }

    if(found == true) {

#ifdef BITMAP_RB_ONLY
        bitmap_rb_t
#endif /* BITMAP_RB_ONLY */
#ifdef FL_RB_ONLY
        freelist_rb_t
#endif /* FL_RB_ONLY */
            *encapsulated_rb = 
#ifdef BITMAP_RB_ONLY
                (bitmap_rb_t *)
#endif /* BITMAP_RB_ONLY */
#ifdef FL_RB_ONLY
                (freelist_rb_t *)
#endif /* FL_RB_ONLY */
                ((char *)current_raw_block + sizeof(raw_block_header_t));
        
        return_ptr = dmmlib_realloc(encapsulated_rb, ptr, size);
        goto done;

    } else { /* This has to be a big block */

        // The new size is checked and if it is smaller than the one from the
        // original request, the remaining memory is simply released. If it is
        // greater, a new big block is initialized, data is copied there and the
        // old big block gets de-allocated.

        current_raw_block = (raw_block_header_t *)((char *)ptr -
                sizeof(raw_block_header_t));

        size_t full_size = sizeof(raw_block_header_t) + size;

        if(full_size <= current_raw_block->size) {

            size_t remaining_size = current_raw_block->size - full_size;
            current_raw_block->size = full_size;

            // FIXME This is mmap-specific
            munmap((void *)((char *)current_raw_block +
                        current_raw_block->size), remaining_size);

#ifdef WITH_ALLOCATOR_STATS
            systemallocator.dmm_stats.total_mem_allocated -=
                remaining_size;
            TRACE_2("dmmlib - ms all %zu\n",
                    systemallocator.dmm_stats.total_mem_allocated);
#ifdef REQUEST_SIZE_INFO
            systemallocator.dmm_stats.total_mem_requested -=
                remaining_size;
            TRACE_2("dmmlib - ms req %zu\n",
                    systemallocator.dmm_stats.total_mem_requested);
#endif /* REQUEST_SIZE_INFO */
            systemallocator.dmm_stats.num_realloc++;
#endif /* WITH_ALLOCATOR_STATS */

            return_ptr = ptr;
            goto done;

        } else {

            size_t size_diff = full_size - current_raw_block->size;

            raw_block_header_t *new_block = create_raw_block(full_size,
                    BIGBLOCK);

            if(new_block == NULL) {

                return_ptr = NULL;
                goto done;

            } else {

                memcpy((void *)((char *)new_block +
                            sizeof(raw_block_header_t)), ptr,
                        current_raw_block->size - sizeof(raw_block_header_t));

                release_memory(current_raw_block);

#ifdef WITH_ALLOCATOR_STATS
                systemallocator.dmm_stats.total_mem_allocated +=
                    size_diff;
                TRACE_2("dmmlib - ms all %zu\n",
                        systemallocator.dmm_stats.total_mem_allocated);
#ifdef REQUEST_SIZE_INFO
                systemallocator.dmm_stats.total_mem_requested +=
                    size_diff;
                TRACE_2("dmmlib - ms req %zu\n",
                        systemallocator.dmm_stats.total_mem_requested);
#endif /* REQUEST_SIZE_INFO */
                systemallocator.dmm_stats.num_realloc++;
#endif /* WITH_ALLOCATOR_STATS */

                return_ptr = (void *)((char *)new_block +
                        sizeof(raw_block_header_t));
                goto done;
            }
        }
    }

done:

    TRACE_1("dmmlib - r %p %p %zu\n", ptr, return_ptr, size);

    return return_ptr;

}