File : s-secsta-static.adb
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S Y S T E M . S E C O N D A R Y _ S T A C K --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2012, 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 Unchecked_Conversion;
33
34 package body System.Secondary_Stack is
35
36 use type SSE.Storage_Offset;
37
38 type Memory is array (Mark_Address range <>) of SSE.Storage_Element;
39
40 type Stack_Id is record
41 Top : Mark_Address;
42 Last : Mark_Address;
43 Mem : Memory (1 .. Mark_Address'Last);
44 end record;
45 pragma Suppress_Initialization (Stack_Id);
46
47 type Stack_Ptr is access Stack_Id;
48
49 function From_Addr is new Unchecked_Conversion (Address, Stack_Ptr);
50
51 function Get_Sec_Stack return Stack_Ptr;
52
53 -----------------
54 -- SS_Allocate --
55 -----------------
56
57 procedure SS_Allocate
58 (Address : out System.Address;
59 Storage_Size : SSE.Storage_Count)
60 is
61 Max_Align : constant Mark_Address :=
62 Mark_Address (Standard'Maximum_Alignment);
63 Max_Size : constant Mark_Address :=
64 ((Mark_Address (Storage_Size) + Max_Align - 1)
65 / Max_Align) * Max_Align;
66 Sec_Stack : constant Stack_Ptr := Get_Sec_Stack;
67
68 begin
69 if Sec_Stack.Top + Max_Size > Sec_Stack.Last then
70 raise Storage_Error;
71 end if;
72
73 Address := Sec_Stack.Mem (Sec_Stack.Top)'Address;
74 Sec_Stack.Top := Sec_Stack.Top + Max_Size;
75 end SS_Allocate;
76
77 -------------
78 -- SS_Init --
79 -------------
80
81 procedure SS_Init
82 (Stk : System.Address;
83 Size : Natural := Default_Secondary_Stack_Size)
84 is
85 Stack : constant Stack_Ptr := From_Addr (Stk);
86 begin
87 pragma Assert (Size >= 2 * Mark_Address'Max_Size_In_Storage_Elements);
88 Stack.Top := Stack.Mem'First;
89 Stack.Last :=
90 Mark_Address (Size) - 2 * Mark_Address'Max_Size_In_Storage_Elements;
91 end SS_Init;
92
93 -------------
94 -- SS_Mark --
95 -------------
96
97 function SS_Mark return Mark_Id is
98 begin
99 return (Mark_Addr => Get_Sec_Stack.Top, Unused => Null_Address);
100 end SS_Mark;
101
102 ----------------
103 -- SS_Release --
104 ----------------
105
106 procedure SS_Release (M : Mark_Id) is
107 begin
108 Get_Sec_Stack.Top := M.Mark_Addr;
109 end SS_Release;
110
111 -------------------------
112 -- Package Elaboration --
113 -------------------------
114
115 -- Allocate a secondary stack for the main program to use
116
117 -- We make sure that the stack has maximum alignment. Some systems require
118 -- this (e.g. Sun), and in any case it is a good idea for efficiency.
119
120 Stack : aliased Memory (1 .. Mark_Address (Default_Secondary_Stack_Size));
121 for Stack'Alignment use Standard'Maximum_Alignment;
122
123 Stack_Address : constant Address := Stack'Address;
124
125 function Get_Sec_Stack return Stack_Ptr is
126 begin
127 return From_Addr (Stack_Address);
128 end Get_Sec_Stack;
129
130 begin
131 SS_Init (Stack_Address, Default_Secondary_Stack_Size);
132 end System.Secondary_Stack;