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

 *                                                                       *

 * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith.       *

 * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *

 *                                                                       *

 * This library is free software; you can redistribute it and/or         *

 * modify it under the terms of EITHER:                                  *

 *   (1) The GNU Lesser General Public License as published by the Free  *

 *       Software Foundation; either version 2.1 of the License, or (at  *

 *       your option) any later version. The text of the GNU Lesser      *

 *       General Public License is included with this library in the     *

 *       file LICENSE.TXT.                                               *

 *   (2) The BSD-style license that is included with this library in     *

 *       the file LICENSE-BSD.TXT.                                       *

 *                                                                       *

 * This library is distributed in the hope that it will be useful,       *

 * but WITHOUT ANY WARRANTY; without even the implied warranty of        *

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *

 * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *

 *                                                                       *

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

#ifndef _ODE_OBSTACK_H_

#define _ODE_OBSTACK_H_

#include "object.h" 

// each obstack Arena pointer points to a block of this many bytes

#define dOBSTACK_ARENA_SIZE 16384

struct dObStack : public dBase {

  struct Arena {

    Arena *next;	// next arena in linked list

    size_t used;		// total number of bytes used in this arena, counting

  };			//   this header

  Arena *first;		// head of the arena linked list. 0 if no arenas yet

  Arena *last;		// arena where blocks are currently being allocated

  // used for iterator

  Arena *current_arena;

  size_t current_ofs;

  dObStack();

  ~dObStack();

  void *alloc (int num_bytes);

  // allocate a block in the last arena, allocating a new arena if necessary.

  // it is a runtime error if num_bytes is larger than the arena size.

  void freeAll();

  // free all blocks in all arenas. this does not deallocate the arenas

  // themselves, so future alloc()s will reuse them.

  void *rewind();

  // rewind the obstack iterator, and return the address of the first

  // allocated block. return 0 if there are no allocated blocks.

  void *next (int num_bytes);

  // return the address of the next allocated block. 'num_bytes' is the size

  // of the previous block. this returns null if there are no more arenas.

  // the sequence of 'num_bytes' parameters passed to next() during a

  // traversal of the list must exactly match the parameters passed to alloc().

};

#endif