File : 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) 1992-2011, 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 3, 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. --
17 -- --
18 -- --
19 -- --
20 -- --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
29 -- --
30 ------------------------------------------------------------------------------
31
32 with System.Memory;
33
34 with Ada.Unchecked_Conversion;
35
36 package body System.Pool_Local is
37
38 package SSE renames System.Storage_Elements;
39 use type SSE.Storage_Offset;
40
41 Pointer_Size : constant SSE.Storage_Offset := Address'Size / Storage_Unit;
42 Pointers_Size : constant SSE.Storage_Offset := 2 * Pointer_Size;
43
44 type Acc_Address is access all Address;
45 function To_Acc_Address is
46 new Ada.Unchecked_Conversion (Address, Acc_Address);
47
48 -----------------------
49 -- Local Subprograms --
50 -----------------------
51
52 function Next (A : Address) return Acc_Address;
53 pragma Inline (Next);
54 -- Given an address of a block, return an access to the next block
55
56 function Prev (A : Address) return Acc_Address;
57 pragma Inline (Prev);
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
115 -- Comment needed
116
117 if Pool.First /= Null_Address then
118 Prev (Pool.First).all := Null_Address;
119 end if;
120 else
121 Next (Prev (Allocated).all).all := Next (Allocated).all;
122 end if;
123
124 if Next (Allocated).all /= Null_Address then
125 Prev (Next (Allocated).all).all := Prev (Allocated).all;
126 end if;
127
128 Memory.Free (Allocated);
129 end Deallocate;
130
131 --------------
132 -- Finalize --
133 --------------
134
135 procedure Finalize (Pool : in out Unbounded_Reclaim_Pool) is
136 N : System.Address := Pool.First;
137 Allocated : System.Address;
138
139 begin
140 while N /= Null_Address loop
141 Allocated := N;
142 N := Next (N).all;
143 Memory.Free (Allocated);
144 end loop;
145 end Finalize;
146
147 ----------
148 -- Next --
149 ----------
150
151 function Next (A : Address) return Acc_Address is
152 begin
153 return To_Acc_Address (A);
154 end Next;
155
156 ----------
157 -- Prev --
158 ----------
159
160 function Prev (A : Address) return Acc_Address is
161 begin
162 return To_Acc_Address (A + Pointer_Size);
163 end Prev;
164
165 end System.Pool_Local;