/*
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations
 * under the License.
 *
 * The Initial Developer of this code is David Baum.
 * Portions created by David Baum are Copyright (C) 1999 David Baum.
 * All Rights Reserved.
 *
 * Portions created by John Hansen are Copyright (C) 2005 John Hansen.
 * All Rights Reserved.
 *
 */

#include "AutoFree.h"

AutoFreeGroup& GetAutoFreeGroup()
{
	static AutoFreeGroup afGroup;

	return afGroup;
}


AutoFreeGroup::AutoFreeGroup()
{
	head_.next_ = &tail_;
	head_.prev_ = 0;
	tail_.next_ = 0;
	tail_.prev_ = &head_;
}


void* AutoFreeGroup::allocate(size_t n)
{
	// allocate memory plus overhead for link
	Link *link = (Link *) ::operator new(n + sizeof(Link));

	// link memory into pool list
	link->next_ = head_.next_;
	link->prev_ = &head_;
	link->next_->prev_ = link;
	link->prev_->next_ = link;

	// return pointer to memory past the link
	return (void *)((char *)link + sizeof(Link));
}


void AutoFreeGroup::free(void *ptr)
{
	if (ptr==0) return;

	// determine pointer to link
	Link *link = (Link *)((char *)ptr - sizeof(Link));

	dispose(link);
}


void AutoFreeGroup::dispose(Link *link)
{
	// unlink memory from pool list
	link->prev_->next_ = link->next_;
	link->next_->prev_ = link->prev_;

	// free the memory
	::operator delete((void*)link);
}


void AutoFreeGroup::freeAll()
{
	Link *link;

	while((link = head_.next_)->next_ != 0)
	{
		dispose(link);
	}
}