/*
 *   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   slab.h
 * \author Iraklis Anagnostopoulos (irasklis@microlab.ntua.gr)
 * \date   March 2014
 * \brief  Slab-related prototypes
 */

#ifndef DEALY_SLAB_H
#define DEALY_SLAB_H
#include <stddef.h>

#include "dmmlib/lists.h"

/** The header structure of every memory block inside a heap. */
typedef struct slab_block_header_s {
    SLIST_ENTRY(slab_block_header_s) pointers;
} slab_block_header_t;

/** The head element of a singly-linked list of slab_block_header_t records */
SLIST_HEAD(slab_head_s, slab_block_header_s);

/** Data structure of the required elements for a free-list organized raw block.
 */
typedef struct slab_rb_s {
    size_t remaining_size; /**< The remaining size for new memory blocks. */
    size_t handling_size; /**< The size that the slab raw block handles. */
    slab_block_header_t *border_ptr; /**< Pointer to the memory block
                                       initialized last. */
    struct slab_head_s fl_head; /**< Head of the free list of
                                     memory blocks. */
    slab_block_header_t *fl_tail; /**< The tail of the free list. */
} slab_rb_t;

/** Initializes meta-data of a slab raw block.
 *
 * @param address        The address of the slab metadata
 * @param available_size The available size of the raw block for slab
 *                       metadata and memory blocks
 */
void initialize_slab(void *address, size_t available_size);

/** Tries to allocate memory from a specific slab raw block.
 *
 * @param raw_block  Pointer to the slab raw block.
 * @param size       Requested allocation size in bytes.
 *
 * @return The pointer to the memory location.
 */
void * slab_malloc(slab_rb_t *raw_block, size_t size);

/** Frees the memory block inside of a specific slab raw block.
 *
 * @param raw_block  Pointer to the slab raw block.
 * @param ptr        Pointer to the memory block to be freed.
 */
void slab_free(slab_rb_t *raw_block, void *ptr);

#endif /* DEALY_SLAB_H */