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 #include <ode/common.h>

    24 #include <ode/error.h>

    25 #include <ode/memory.h>

    26 #include "obstack.h"

    27 

    28 //****************************************************************************

    29 // macros and constants

    30 

    31 #define ROUND_UP_OFFSET_TO_EFFICIENT_SIZE(arena,ofs) \

    32   ofs = (size_t) (dEFFICIENT_SIZE( ((intP)(arena)) + ofs ) - ((intP)(arena)) );

    33 

    34 #define MAX_ALLOC_SIZE \

    35   ((size_t)(dOBSTACK_ARENA_SIZE - sizeof (Arena) - EFFICIENT_ALIGNMENT + 1))

    36 

    37 //****************************************************************************

    38 // dObStack

    39 

    40 dObStack::dObStack()

    41 {

    42   first = 0;

    43   last = 0;

    44   current_arena = 0;

    45   current_ofs = 0;

    46 }

    47 

    48 

    49 dObStack::~dObStack()

    50 {

    51   // free all arenas

    52   Arena *a,*nexta;

    53   a = first;

    54   while (a) {

    55     nexta = a->next;

    56     dFree (a,dOBSTACK_ARENA_SIZE);

    57     a = nexta;

    58   }

    59 }

    60 

    61 

    62 void *dObStack::alloc (int num_bytes)

    63 {

    64 

    65 

    66   // allocate or move to a new arena if necessary

    67   if (!first) {

    68     // allocate the first arena if necessary

    69     first = last = (Arena *) dAlloc (dOBSTACK_ARENA_SIZE);

    70     first->next = 0;

    71     first->used = sizeof (Arena);

    72     ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (first,first->used);

    73   }

    74   else {

    75     // we already have one or more arenas, see if a new arena must be used

    76     if ((last->used + num_bytes) > dOBSTACK_ARENA_SIZE) {

    77       if (!last->next) {

    78 	last->next = (Arena *) dAlloc (dOBSTACK_ARENA_SIZE);

    79 	last->next->next = 0;

    80       }

    81       last = last->next;

    82       last->used = sizeof (Arena);

    83       ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (last,last->used);

    84     }

    85   }

    86 

    87   // allocate an area in the arena

    88   char *c = ((char*) last) + last->used;

    89   last->used += num_bytes;

    90   ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (last,last->used);

    91   return c;

    92 }

    93 

    94 

    95 void dObStack::freeAll()

    96 {

    97   last = first;

    98   if (first) {

    99     first->used = sizeof(Arena);

   100     ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (first,first->used);

   101   }

   102 }

   103 

   104 

   105 void *dObStack::rewind()

   106 {

   107   current_arena = first;

   108   current_ofs = sizeof (Arena);

   109   if (current_arena) {

   110     ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (current_arena,current_ofs)

   111     return ((char*) current_arena) + current_ofs;

   112   }

   113   else return 0;

   114 }

   115 

   116 

   117 void *dObStack::next (int num_bytes)

   118 {

   119   // this functions like alloc, except that no new storage is ever allocated

   120   if (!current_arena) return 0;

   121   current_ofs += num_bytes;

   122   ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (current_arena,current_ofs);

   123   if (current_ofs >= current_arena->used) {

   124     current_arena = current_arena->next;

   125     if (!current_arena) return 0;

   126     current_ofs = sizeof (Arena);

   127     ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (current_arena,current_ofs);

   128   }

   129   return ((char*) current_arena) + current_ofs;

   130 }