WebCore/Arena.h

   1 /*
   2  * Copyright (C) 1998-2000 Netscape Communications Corporation.
   3  * Copyright (C) 2003-6 Apple Computer
   4  *
   5  * Other contributors:
   6  *   Nick Blievers <nickb@adacel.com.au>
   7  *   Jeff Hostetler <jeff@nerdone.com>
   8  *   Tom Rini <trini@kernel.crashing.org>
   9  *   Raffaele Sena <raff@netwinder.org>
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; either
  14  * version 2.1 of the License, or (at your option) any later version.
  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 GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  24  *
  25  * Alternatively, the contents of this file may be used under the terms
  26  * of either the Mozilla Public License Version 1.1, found at
  27  * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
  28  * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
  29  * (the "GPL"), in which case the provisions of the MPL or the GPL are
  30  * applicable instead of those above.  If you wish to allow use of your
  31  * version of this file only under the terms of one of those two
  32  * licenses (the MPL or the GPL) and not to allow others to use your
  33  * version of this file under the LGPL, indicate your decision by
  34  * deletingthe provisions above and replace them with the notice and
  35  * other provisions required by the MPL or the GPL, as the case may be.
  36  * If you do not delete the provisions above, a recipient may use your
  37  * version of this file under any of the LGPL, the MPL or the GPL.
  38  */
  39
  40 #ifndef Arena_h
  41 #define Arena_h
  42
  43 #define ARENA_ALIGN_MASK 3
  44
  45 namespace WebCore {
  46
  47 typedef unsigned long uword;
  48
  49 struct Arena {
  50     Arena* next;        // next arena
  51     uword base;         // aligned base address
  52     uword limit;        // end of arena (1+last byte)
  53     uword avail;        // points to next available byte in arena
  54 };
  55
  56 struct ArenaPool {
  57     Arena first;        // first arena in pool list.
  58     Arena* current;     // current arena.
  59     unsigned int arenasize;
  60     uword mask;         // Mask (power-of-2 - 1)
  61 };
  62
  63 void InitArenaPool(ArenaPool *pool, const char *name,
  64                    unsigned int size, unsigned int align);
  65 void FinishArenaPool(ArenaPool *pool);
  66 void FreeArenaPool(ArenaPool *pool);
  67 void* ArenaAllocate(ArenaPool *pool, unsigned int nb);
  68
  69 #define ARENA_ALIGN(pool, n) (((uword)(n) + ARENA_ALIGN_MASK) & ~ARENA_ALIGN_MASK)
  70 #define INIT_ARENA_POOL(pool, name, size) \
  71         InitArenaPool(pool, name, size, ARENA_ALIGN_MASK + 1)
  72
  73 #define ARENA_ALLOCATE(p, pool, nb) \
  74         Arena *_a = (pool)->current; \
  75         unsigned int _nb = ARENA_ALIGN(pool, nb); \
  76         uword _p = _a->avail; \
  77         uword _q = _p + _nb; \
  78         if (_q > _a->limit) \
  79             _p = (uword)ArenaAllocate(pool, _nb); \
  80         else \
  81             _a->avail = _q; \
  82         p = (void *)_p;
  83
  84 #define ARENA_GROW(p, pool, size, incr) \
  85         Arena *_a = (pool)->current; \
  86         unsigned int _incr = ARENA_ALIGN(pool, incr); \
  87         uword _p = _a->avail; \
  88         uword _q = _p + _incr; \
  89         if (_p == (uword)(p) + ARENA_ALIGN(pool, size) && \
  90             _q <= _a->limit) { \
  91             _a->avail = _q; \
  92         } else { \
  93             p = ArenaGrow(pool, p, size, incr); \
  94         }
  95
  96 #define ARENA_MARK(pool) ((void *) (pool)->current->avail)
  97 #define UPTRDIFF(p,q) ((uword)(p) - (uword)(q))
  98
  99 #ifdef DEBUG
 100 #define FREE_PATTERN 0xDA
 101 #define CLEAR_UNUSED(a) ASSERT((a)->avail <= (a)->limit); \
 102                         memset((void*)(a)->avail, FREE_PATTERN, \
 103                             (a)->limit - (a)->avail)
 104 #define CLEAR_ARENA(a)  memset((void*)(a), FREE_PATTERN, \
 105                             (a)->limit - (uword)(a))
 106 #else
 107 #define CLEAR_UNUSED(a)
 108 #define CLEAR_ARENA(a)
 109 #endif
 110
 111 #define ARENA_RELEASE(pool, mark) \
 112          char *_m = (char *)(mark); \
 113          Arena *_a = (pool)->current; \
 114          if (UPTRDIFF(_m, _a->base) <= UPTRDIFF(_a->avail, _a->base)) { \
 115              _a->avail = (uword)ARENA_ALIGN(pool, _m); \
 116              CLEAR_UNUSED(_a); \
 117          } else { \
 118              ArenaRelease(pool, _m); \
 119          }
 120
 121 #define ARENA_DESTROY(pool, a, pnext) \
 122          if ((pool)->current == (a)) (pool)->current = &(pool)->first; \
 123          *(pnext) = (a)->next; \
 124          CLEAR_ARENA(a); \
 125          fastFree(a); \
 126          (a) = 0;
 127
 128 }
 129
 130 #endif