/lib/ode/ode_source/ode/src/obstack.h

 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 "objects.h" 
27
28// each obstack Arena pointer points to a block of this many bytes
29#define dOBSTACK_ARENA_SIZE 16384
30
31
32struct 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