/********************************************************************
	
	memory.c - memory handling routines

  Niksa Orlic, 2005-03-22

********************************************************************/

#include <stdlib.h>
#include <string.h>

#include "memory.h"
#include "error.h"
//#include "message.h"

#define SLOWLIST 1

static memory_object* memory_object_list_begin = NULL;
static memory_object* memory_object_list_end = NULL;


/*
	Initialize the list of memory objects
*/
void mem_init()
{
	memory_object_list_begin = (memory_object*)malloc(sizeof(memory_object));
	memory_object_list_begin->next = NULL;
	memory_object_list_begin->prev = NULL;
	memory_object_list_begin->data = NULL;
	memory_object_list_end = memory_object_list_begin;
}

/*
	Clean up the list of memory objects
*/
void mem_close()
{
	memory_object *it = memory_object_list_begin;
	memory_object *old_object;

	while (it != NULL)
	{		
		old_object = it;
		it = it->next;
#if SLOWLIST
		if (old_object->data != NULL)
			free(old_object->data);
		free(old_object);
#else
		mem_free(old_object);
#endif
	}
}

/*
	Allocate the new block of memory and append it into the list
*/
void* mem_alloc(size_t s)
{
#if SLOWLIST
	memory_object *wrapper = (memory_object*)malloc(sizeof(memory_object));	
#else
	memory_object *wrapper = (memory_object*)malloc(sizeof(memory_object) + s);
#endif	
	if (wrapper == NULL)
		return NULL;

#if SLOWLIST
	wrapper->data = malloc(s);
	if (wrapper->data == NULL)
		return NULL;
#else	
	wrapper->data = (char*)wrapper + sizeof(memory_object);
#endif

	wrapper->next = NULL;
	wrapper->prev = memory_object_list_end;
	memory_object_list_end->next = wrapper;
	memory_object_list_end = wrapper;

	if (memory_object_list_end == NULL)
		die(26);

	return wrapper->data;
}


/*
	Reallocate the new block of memory and append it into the list
*/
void* mem_realloc(char* old_block, int s)
{
	memory_object *wrapper;
	memory_object *prev, *next;

	void *new_block;

	prev = next = NULL;

#if SLOWLIST
	/* find the block */
	{
		memory_object *it = memory_object_list_begin;

		while (it != NULL)
		{
			if (it->data == old_block)
			{				
				break;
			}

			it = it->next;
		}
	
		it->data = realloc(it->data, s);
		
		return it->data;		
	}
#else
	prev = ((memory_object*)(old_block - sizeof(memory_object)))->prev;
	next = ((memory_object*)(old_block - sizeof(memory_object)))->next;

	new_block = realloc(old_block - sizeof(memory_object), sizeof(memory_object) + s);

	if (new_block == NULL)
	{
		mem_free(old_block);
		return NULL;
	}

	if ((old_block - sizeof(memory_object)) == new_block)
		return old_block;

	wrapper = (memory_object*) new_block;

	if (prev != NULL)
		prev->next = wrapper;
	wrapper->prev = prev;

	if (next != NULL)
		next->prev = wrapper;
	wrapper->next = next;

	mem_free(old_block);

	return wrapper->data;
#endif
}

/*
	Free the block of memory
*/
void mem_free(char* old_block)
{	
	memory_object *prev, *next;

	prev = next = NULL;

	if (old_block == NULL)
		return;	

#if SLOWLIST
	/* find the block */
	{
		memory_object *it = memory_object_list_begin;

		while (it != NULL)
		{
			if (it->data == old_block)
			{
				prev = it->prev;
				next = it->next;

				if (prev == NULL)
				{
					int a = 1;
				}

				free(old_block);
				free(it);

				break;
			}

			it = it->next;
		}

		if (it == NULL)
			return;
	}
#else
	prev = ((memory_object*)(old_block - sizeof(memory_object)))->prev;
	next = ((memory_object*)(old_block - sizeof(memory_object)))->next;

	free(old_block - sizeof(memory_object));
#endif

	if (prev != NULL)	
		prev->next = next;
	
	if (next != NULL)
		next->prev = prev;

	if (next == NULL)
		memory_object_list_end = prev;

	if (memory_object_list_end == NULL)
	{
		int a = 1;
	}

}