/*

 * Copyright (C) 1998-2000 Netscape Communications Corporation.

 * Copyright (C) 2003-6 Apple Computer

 * Copyright (C) Research In Motion Limited 2010. All rights reserved.

 *

 * Other contributors:

 *   Nick Blievers <nickb@adacel.com.au>

 *   Jeff Hostetler <jeff@nerdone.com>

 *   Tom Rini <trini@kernel.crashing.org>

 *   Raffaele Sena <raff@netwinder.org>

 *

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

 * modify it under the terms of 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.

 *

 * 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 GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 *

 * Alternatively, the contents of this file may be used under the terms

 * of either the Mozilla Public License Version 1.1, found at

 * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public

 * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html

 * (the "GPL"), in which case the provisions of the MPL or the GPL are

 * applicable instead of those above.  If you wish to allow use of your

 * version of this file only under the terms of one of those two

 * licenses (the MPL or the GPL) and not to allow others to use your

 * version of this file under the LGPL, indicate your decision by

 * deletingthe provisions above and replace them with the notice and

 * other provisions required by the MPL or the GPL, as the case may be.

 * If you do not delete the provisions above, a recipient may use your

 * version of this file under any of the LGPL, the MPL or the GPL.

 */

#ifndef Arena_h

#define Arena_h

#include <wtf/FastMalloc.h>

// FIXME: We'd always like to use AllocAlignmentInteger for Arena alignment

// but there is concern over the memory growth this may cause.

#ifdef WTF_USE_ARENA_ALLOC_ALIGNMENT_INTEGER

#define ARENA_ALIGN_MASK (sizeof(WTF::AllocAlignmentInteger) - 1)

#else

#define ARENA_ALIGN_MASK 3

#endif

namespace WebCore {

typedef uintptr_t uword;

struct Arena {

    Arena* next;        // next arena

    uword base;         // aligned base address

    uword limit;        // end of arena (1+last byte)

    uword avail;        // points to next available byte in arena

};

struct ArenaPool {

    Arena first;        // first arena in pool list.

    Arena* current;     // current arena.

    unsigned int arenasize;

    uword mask;         // Mask (power-of-2 - 1)

};

void InitArenaPool(ArenaPool *pool, const char *name, 

                   unsigned int size, unsigned int align);

void FinishArenaPool(ArenaPool *pool);

void FreeArenaPool(ArenaPool *pool);

void* ArenaAllocate(ArenaPool *pool, unsigned int nb);

#define ARENA_ALIGN(n) (((uword)(n) + ARENA_ALIGN_MASK) & ~ARENA_ALIGN_MASK)

#define INIT_ARENA_POOL(pool, name, size) \

        InitArenaPool(pool, name, size, ARENA_ALIGN_MASK + 1)

#define ARENA_ALLOCATE(p, pool, nb) \

        Arena *_a = (pool)->current; \

        unsigned int _nb = ARENA_ALIGN(nb); \

        uword _p = _a->avail; \

        uword _q = _p + _nb; \

        if (_q > _a->limit) \

            _p = (uword)ArenaAllocate(pool, _nb); \

        else \

            _a->avail = _q; \

        p = (void *)_p;

#define ARENA_GROW(p, pool, size, incr) \

        Arena *_a = (pool)->current; \

        unsigned int _incr = ARENA_ALIGN(incr); \

        uword _p = _a->avail; \

        uword _q = _p + _incr; \

        if (_p == (uword)(p) + ARENA_ALIGN(size) && \

            _q <= _a->limit) { \

            _a->avail = _q; \

        } else { \

            p = ArenaGrow(pool, p, size, incr); \

        }

#define ARENA_MARK(pool) ((void *) (pool)->current->avail)

#define UPTRDIFF(p,q) ((uword)(p) - (uword)(q))     

#ifdef DEBUG

#define FREE_PATTERN 0xDA

#define CLEAR_UNUSED(a) ASSERT((a)->avail <= (a)->limit); \

                        memset((void*)(a)->avail, FREE_PATTERN, \

                            (a)->limit - (a)->avail)

#define CLEAR_ARENA(a)  memset((void*)(a), FREE_PATTERN, \

                            (a)->limit - (uword)(a))

#else

#define CLEAR_UNUSED(a)

#define CLEAR_ARENA(a)

#endif

#define ARENA_RELEASE(pool, mark) \

         char *_m = (char *)(mark); \

         Arena *_a = (pool)->current; \

         if (UPTRDIFF(_m, _a->base) <= UPTRDIFF(_a->avail, _a->base)) { \

             _a->avail = (uword)ARENA_ALIGN(_m); \

             CLEAR_UNUSED(_a); \

         } else { \

             ArenaRelease(pool, _m); \

         }

#define ARENA_DESTROY(pool, a, pnext) \

         if ((pool)->current == (a)) (pool)->current = &(pool)->first; \

         *(pnext) = (a)->next; \

         CLEAR_ARENA(a); \

         fastFree(a); \

         (a) = 0;

}

#endif