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 --                                                                          --
  10 --          Copyright (C) 1992-2001, Free Software Foundation, Inc.         --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNAT was originally developed  by the GNAT team at  New York University. --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 with System.Memory;
  36 with System.Storage_Elements;
  37 with System.Address_To_Access_Conversions;
  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    package Addr is new Address_To_Access_Conversions (Address);
  49
  50    -----------------------
  51    -- Local Subprograms --
  52    -----------------------
  53
  54    function Next (A : Address) return Acc_Address;
  55    --  Given an address of a block, return an access to the next block
  56
  57    function Prev (A : Address) return Acc_Address;
  58    --  Given an address of a block, return an access to the previous block
  59
  60    --------------
  61    -- Allocate --
  62    --------------
  63
  64    procedure Allocate
  65      (Pool         : in out Unbounded_Reclaim_Pool;
  66       Address      : out System.Address;
  67       Storage_Size : SSE.Storage_Count;
  68       Alignment    : SSE.Storage_Count)
  69    is
  70       pragma Warnings (Off, Alignment);
  71
  72       Allocated : constant System.Address :=
  73                     Memory.Alloc
  74                       (Memory.size_t (Storage_Size + Pointers_Size));
  75
  76    begin
  77       --  The call to Alloc returns an address whose alignment is compatible
  78       --  with the worst case alignment requirement for the machine; thus the
  79       --  Alignment argument can be safely ignored.
  80
  81       if Allocated = Null_Address then
  82          raise Storage_Error;
  83       else
  84          Address := Allocated + Pointers_Size;
  85          Next (Allocated).all := Pool.First;
  86          Prev (Allocated).all := Null_Address;
  87
  88          if Pool.First /= Null_Address then
  89             Prev (Pool.First).all := Allocated;
  90          end if;
  91
  92          Pool.First := Allocated;
  93       end if;
  94    end Allocate;
  95
  96    ----------------
  97    -- Deallocate --
  98    ----------------
  99
 100    procedure Deallocate
 101      (Pool         : in out Unbounded_Reclaim_Pool;
 102       Address      : System.Address;
 103       Storage_Size : SSE.Storage_Count;
 104       Alignment    : SSE.Storage_Count)
 105    is
 106       pragma Warnings (Off, Storage_Size);
 107       pragma Warnings (Off, Alignment);
 108
 109       Allocated : constant System.Address := Address - Pointers_Size;
 110
 111    begin
 112       if Prev (Allocated).all = Null_Address then
 113          Pool.First := Next (Allocated).all;
 114          Prev (Pool.First).all := Null_Address;
 115       else
 116          Next (Prev (Allocated).all).all := Next (Allocated).all;
 117       end if;
 118
 119       if Next (Allocated).all /= Null_Address then
 120          Prev (Next (Allocated).all).all := Prev (Allocated).all;
 121       end if;
 122
 123       Memory.Free (Allocated);
 124    end Deallocate;
 125
 126    --------------
 127    -- Finalize --
 128    --------------
 129
 130    procedure Finalize (Pool : in out Unbounded_Reclaim_Pool) is
 131       N         : System.Address := Pool.First;
 132       Allocated : System.Address;
 133
 134    begin
 135       while N /= Null_Address loop
 136          Allocated := N;
 137          N := Next (N).all;
 138          Memory.Free (Allocated);
 139       end loop;
 140    end Finalize;
 141
 142    ----------
 143    -- Next --
 144    ----------
 145
 146    function Next (A : Address) return Acc_Address is
 147    begin
 148       return Acc_Address (Addr.To_Pointer (A));
 149    end Next;
 150
 151    ----------
 152    -- Prev --
 153    ----------
 154
 155    function Prev (A : Address) return Acc_Address is
 156    begin
 157       return Acc_Address (Addr.To_Pointer (A + Pointer_Size));
 158    end Prev;
 159
 160 end System.Pool_Local;