gcc/ada/s-pooloc.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                    S Y S T E M . P O O L _ L O C A L                     --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2002, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 with System.Memory;
  35 with System.Storage_Elements;
  36
  37 with Unchecked_Conversion;
  38
  39 package body System.Pool_Local is
  40
  41    package SSE renames System.Storage_Elements;
  42    use type SSE.Storage_Offset;
  43
  44    Pointer_Size  : constant SSE.Storage_Offset := Address'Size / Storage_Unit;
  45    Pointers_Size : constant SSE.Storage_Offset := 2 * Pointer_Size;
  46
  47    type Acc_Address is access all Address;
  48    function To_Acc_Address is new Unchecked_Conversion (Address, Acc_Address);
  49
  50    -----------------------
  51    -- Local Subprograms --
  52    -----------------------
  53
  54    function Next (A : Address) return Acc_Address;
  55    pragma Inline (Next);
  56    --  Given an address of a block, return an access to the next block
  57
  58    function Prev (A : Address) return Acc_Address;
  59    pragma Inline (Prev);
  60    --  Given an address of a block, return an access to the previous block
  61
  62    --------------
  63    -- Allocate --
  64    --------------
  65
  66    procedure Allocate
  67      (Pool         : in out Unbounded_Reclaim_Pool;
  68       Address      : out System.Address;
  69       Storage_Size : SSE.Storage_Count;
  70       Alignment    : SSE.Storage_Count)
  71    is
  72       pragma Warnings (Off, Alignment);
  73
  74       Allocated : constant System.Address :=
  75                     Memory.Alloc
  76                       (Memory.size_t (Storage_Size + Pointers_Size));
  77
  78    begin
  79       --  The call to Alloc returns an address whose alignment is compatible
  80       --  with the worst case alignment requirement for the machine; thus the
  81       --  Alignment argument can be safely ignored.
  82
  83       if Allocated = Null_Address then
  84          raise Storage_Error;
  85       else
  86          Address := Allocated + Pointers_Size;
  87          Next (Allocated).all := Pool.First;
  88          Prev (Allocated).all := Null_Address;
  89
  90          if Pool.First /= Null_Address then
  91             Prev (Pool.First).all := Allocated;
  92          end if;
  93
  94          Pool.First := Allocated;
  95       end if;
  96    end Allocate;
  97
  98    ----------------
  99    -- Deallocate --
 100    ----------------
 101
 102    procedure Deallocate
 103      (Pool         : in out Unbounded_Reclaim_Pool;
 104       Address      : System.Address;
 105       Storage_Size : SSE.Storage_Count;
 106       Alignment    : SSE.Storage_Count)
 107    is
 108       pragma Warnings (Off, Storage_Size);
 109       pragma Warnings (Off, Alignment);
 110
 111       Allocated : constant System.Address := Address - Pointers_Size;
 112
 113    begin
 114       if Prev (Allocated).all = Null_Address then
 115          Pool.First := Next (Allocated).all;
 116          Prev (Pool.First).all := Null_Address;
 117       else
 118          Next (Prev (Allocated).all).all := Next (Allocated).all;
 119       end if;
 120
 121       if Next (Allocated).all /= Null_Address then
 122          Prev (Next (Allocated).all).all := Prev (Allocated).all;
 123       end if;
 124
 125       Memory.Free (Allocated);
 126    end Deallocate;
 127
 128    --------------
 129    -- Finalize --
 130    --------------
 131
 132    procedure Finalize (Pool : in out Unbounded_Reclaim_Pool) is
 133       N         : System.Address := Pool.First;
 134       Allocated : System.Address;
 135
 136    begin
 137       while N /= Null_Address loop
 138          Allocated := N;
 139          N := Next (N).all;
 140          Memory.Free (Allocated);
 141       end loop;
 142    end Finalize;
 143
 144    ----------
 145    -- Next --
 146    ----------
 147
 148    function Next (A : Address) return Acc_Address is
 149    begin
 150       return To_Acc_Address (A);
 151    end Next;
 152
 153    ----------
 154    -- Prev --
 155    ----------
 156
 157    function Prev (A : Address) return Acc_Address is
 158    begin
 159       return To_Acc_Address (A + Pointer_Size);
 160    end Prev;
 161
 162 end System.Pool_Local;