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
  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