1 /*************************************************************************

     2  *                                                                       *

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

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

     5  *                                                                       *

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

     7  * modify it under the terms of EITHER:                                  *

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

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

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

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

    12  *       file LICENSE.TXT.                                               *

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

    14  *       the file LICENSE-BSD.TXT.                                       *

    15  *                                                                       *

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

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

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

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

    20  *                                                                       *

    21  *************************************************************************/

    22 

    23 #ifndef _ODE_OBSTACK_H_

    24 #define _ODE_OBSTACK_H_

    25 

    26 #include "object.h" 

    27 

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

    29 #define dOBSTACK_ARENA_SIZE 16384

    30 

    31 

    32 struct dObStack : public dBase {

    33   struct Arena {

    34     Arena *next;	// next arena in linked list

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

    36   };			//   this header

    37 

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

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

    40 

    41   // used for iterator

    42   Arena *current_arena;

    43   size_t current_ofs;

    44 

    45   dObStack();

    46   ~dObStack();

    47 

    48   void *alloc (int num_bytes);

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

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

    51 

    52   void freeAll();

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

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

    55 

    56   void *rewind();

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

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

    59 

    60   void *next (int num_bytes);

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

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

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

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

    65 };

    66 

    67 

    68 #endif