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/*************************************************************************
* *
* 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. *
* *
*************************************************************************/
#include <ode/common.h>
#include <ode/error.h>
#include <ode/memory.h>
#include "obstack.h"
//****************************************************************************
// macros and constants
#define ROUND_UP_OFFSET_TO_EFFICIENT_SIZE(arena,ofs) \
ofs = (size_t) (dEFFICIENT_SIZE( ((intP)(arena)) + ofs ) - ((intP)(arena)) );
#define MAX_ALLOC_SIZE \
((size_t)(dOBSTACK_ARENA_SIZE - sizeof (Arena) - EFFICIENT_ALIGNMENT + 1))
//****************************************************************************
// dObStack
dObStack::dObStack()
{
first = 0;
last = 0;
current_arena = 0;
current_ofs = 0;
}
dObStack::~dObStack()
{
// free all arenas
Arena *a,*nexta;
a = first;
while (a) {
nexta = a->next;
dFree (a,dOBSTACK_ARENA_SIZE);
a = nexta;
}
}
void *dObStack::alloc (int num_bytes)
{
if ((size_t)num_bytes > MAX_ALLOC_SIZE) dDebug (0,"num_bytes too large");
// allocate or move to a new arena if necessary
if (!first) {
// allocate the first arena if necessary
first = last = (Arena *) dAlloc (dOBSTACK_ARENA_SIZE);
first->next = 0;
first->used = sizeof (Arena);
ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (first,first->used);
}
else {
// we already have one or more arenas, see if a new arena must be used
if ((last->used + num_bytes) > dOBSTACK_ARENA_SIZE) {
if (!last->next) {
last->next = (Arena *) dAlloc (dOBSTACK_ARENA_SIZE);
last->next->next = 0;
}
last = last->next;
last->used = sizeof (Arena);
ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (last,last->used);
}
}
// allocate an area in the arena
char *c = ((char*) last) + last->used;
last->used += num_bytes;
ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (last,last->used);
return c;
}
void dObStack::freeAll()
{
last = first;
if (first) {
first->used = sizeof(Arena);
ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (first,first->used);
}
}
void *dObStack::rewind()
{
current_arena = first;
current_ofs = sizeof (Arena);
if (current_arena) {
ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (current_arena,current_ofs)
return ((char*) current_arena) + current_ofs;
}
else return 0;
}
void *dObStack::next (int num_bytes)
{
// this functions like alloc, except that no new storage is ever allocated
if (!current_arena) return 0;
current_ofs += num_bytes;
ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (current_arena,current_ofs);
if (current_ofs >= current_arena->used) {
current_arena = current_arena->next;
if (!current_arena) return 0;
current_ofs = sizeof (Arena);
ROUND_UP_OFFSET_TO_EFFICIENT_SIZE (current_arena,current_ofs);
}
return ((char*) current_arena) + current_ofs;
}
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