dmmlib/private-include/block_header.h

/*
 *   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.
 *
 */

/**
 * \file 	block_header.h
 * \author 	Ioannis Koutras (joko@microlab.ntua.gr)
 * \date 	September, 2011
 *  
 * \brief Block header structure and functions, and memory block functions.
 */

#ifndef BLOCK_HEADER_H
#define BLOCK_HEADER_H

#include <stddef.h>
#include <stdbool.h>
#include <dmmlib/heap.h>

/* TODO Add an ifndef guard in case we have other block organizations */
#include "linked_lists/linked_lists.h"

/** The header structure of every memory block inside a heap. */
typedef struct block_header_s {
    size_t size; /**< The LSB represents the availability of the block (1
                   for used, 0 for free), the rest the size of the data
                   part. */
#ifdef FUTURE_FEATURES
    size_t requested_size; /**< The requested size of the data part */
#endif /* FUTURE_FEATURES */
    size_t previous_size; /**< The LSB represents the availability of the
                            previous block, the rest the size of the data
                            part of the previous block in the memory space */
    /* TODO Add an ifndef guard in case we have other block organizations */
    list_node_header_t pointers; /**< The necessary pointers for block
                                   organization. */
#ifdef WITH_OWNERSHIP
    heap_t *heap_owner; /** < A pointer to the heap the current block belongs to */
#endif /* WITH_OWNERSHIP */
} block_header_t;

/**
 * The size of the header in number of bytes
 */
#define HEADER_SIZE sizeof(block_header_t)

/**
 * \brief Get the address of the block header of a memory block.
 *
 * \param ptr The data part of the memory block.
 */
block_header_t * get_header(void *ptr);

/**
 * Get the size of the memory block's data
 *
 * \param ptr The pointer to the data part of the current memory block.
 *
 * \return The size of the data part of the current memory block.
 */
size_t get_size(void *ptr);

#ifdef FUTURE_FEATURES
/**
 * Get the requested size of the memory block's data
 *
 * \param ptr The pointer to the data part of the current memory block.
 *
 * \return The size of the data that was initialy requested for this memory
 * block.
 */
size_t get_requested_size(void *ptr);
#endif /* FUTURE_FEATURES */

/**
 * Get all information of the memory block header's size record
 *
 * \param ptr The pointer to the data part of the current memory block.
 *
 * \return The availability and the size of the data part of the current memory
 * block.
 */
size_t get_size_availability(void *ptr);

/**
 * Set the size of the memory block's data and mark it free
 *
 * \param allocator The pointer to the allocator who manages the block.
 * \param ptr 	The pointer to the data part of the current memory block.
 * \param size 	The size of the data part of the current memory block.
 */
void set_size_and_free(allocator_t *allocator, void *ptr, size_t size);

/**
 * Set the size of the memory block's data and mark it used
 *
 * \param allocator The pointer to the allocator who manages the block.
 * \param ptr 	The pointer to the data part of the current memory block.
 * \param size 	The size of the data part of the current memory block.
 */
void set_size_and_used(allocator_t *allocator, void *ptr, size_t size);

#ifdef FUTURE_FEATURES
/**
 * Set the requested size of memory block's data
 *
 * \param ptr 	The pointer to the data part of the current memory block.
 * \param size 	The requested size for the data part of the current memory
 * block.
 */
void set_requested_size(void *ptr, size_t size);
#endif /* FUTURE_FEATURES */

/**
 * Mark the memory block as used, as well as the previous_size element of the
 * next block if there is one.
 *
 * \param allocator The pointer to the allocator who manages the block.
 * \param ptr 	The pointer to the data part of the memory block.
 */
void mark_used(allocator_t *allocator, void *ptr);

/**
 * Mark the memory block as free, as well as the previous_size element of the
 * next block if there is one.
 *
 * \param allocator The pointer to the allocator who manages the block.
 * \param ptr 	The pointer to the data part of the memory block.
 */
void mark_free(allocator_t *allocator, void *ptr);

/**
 * Set the availability and the size of the previous memory block
 *
 * \param ptr 		The pointer to the data part of the previous memory block.
 * \param previous_size_availability The size for the data part of the previous
 * memory block on data layout level.
 */
void set_previous_size_availability(void *ptr, size_t previous_size_availability);

#ifdef WITH_OWNERSHIP

/**
 * Set the heap owner of a memory block
 *
 * \param ptr 		The pointer to the data part of the memory block.
 * \param heap_owner 	The pointer to the heap owner.
 */
void set_owner(void *ptr, heap_t *heap_owner);

/**
 * Get the heap owner of a memory block
 *
 * \param ptr 	The pointer to the data part of the memory block.
 * \return 	The pointer to the heap owner.
 */
heap_t * get_owner(void *ptr);

#endif /* WITH_OWNERSHIP */

/**
 * Check if a memory block is free
 */
bool is_free(void *ptr);

/**
 * Check if previous block (in the memory space) belongs to a free list
 */
bool is_previous_free(void *ptr);

/**
 * Get the size of the previous block (in the memory space) 
 *
 * \param ptr 	The pointer to the data part of the current memory block.
 */
size_t get_previous_size(void *ptr);

/**
 * Get the size and the availability of the previous block (in the memory
 * space) 
 *
 * \param ptr 	The pointer to the data part of the previous memory block.
 */
size_t get_previous_size_availability(void *ptr);

/**
 * Get the previous memory block on data layout level
 *
 * \param ptr 	The pointer to the data part of the current memory block.
 *
 * \return 	The pointer to the data part of the previous memory block on
 * data layout level. 
 */
void * get_dlprevious(void *ptr);

/**
 * Get the next memory block on data layout level if there is one
 *
 * \param allocator 	The pointer to the allocator who manages the block.
 * \param ptr 		The pointer to the data part of the current memory block.
 *
 * \return The pointer to the next block.
 * \retval NULL There is no next block.
 */
void * get_dlnext(allocator_t *allocator, void *ptr);

#endif /* BLOCK_HEADER_H */