File : s-secsta-zfp.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) 1992-2014, 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 -- This is the HI-E version of this package
33
34 with Unchecked_Conversion;
35
36 package body System.Secondary_Stack is
37
38 use type SSE.Storage_Offset;
39
40 type Memory is array (Mark_Id range <>) of SSE.Storage_Element;
41
42 type Stack_Id is record
43 Top : Mark_Id;
44 Last : Mark_Id;
45 Mem : Memory (1 .. Mark_Id'Last);
46 end record;
47 pragma Suppress_Initialization (Stack_Id);
48
49 type Stack_Ptr is access Stack_Id;
50
51 function From_Addr is new Unchecked_Conversion (Address, Stack_Ptr);
52
53 function Get_Sec_Stack return Stack_Ptr;
54 pragma Import (C, Get_Sec_Stack, "__gnat_get_secondary_stack");
55 -- Return the address of the secondary stack.
56 -- In a multi-threaded environment, Sec_Stack should be a thread-local
57 -- variable.
58 --
59 -- Possible separate implementation of Get_Sec_Stack in a single-threaded
60 -- environment:
61 --
62 -- with System;
63
64 -- package Secondary_Stack is
65 -- function Get_Sec_Stack return System.Address;
66 -- pragma Export (C, Get_Sec_Stack, "__gnat_get_secondary_stack");
67 -- end Secondary_Stack;
68
69 -- pragma Warnings (Off);
70 -- with System.Secondary_Stack; use System.Secondary_Stack;
71 -- pragma Warnings (On);
72
73 -- package body Secondary_Stack is
74
75 -- Chunk : aliased String (1 .. Default_Secondary_Stack_Size);
76 -- for Chunk'Alignment use Standard'Maximum_Alignment;
77
78 -- Initialized : Boolean := False;
79
80 -- function Get_Sec_Stack return System.Address is
81 -- begin
82 -- if not Initialized then
83 -- Initialized := True;
84 -- SS_Init (Chunk'Address);
85 -- end if;
86
87 -- return Chunk'Address;
88 -- end Get_Sec_Stack;
89
90 -- end Secondary_Stack;
91
92 -----------------
93 -- SS_Allocate --
94 -----------------
95
96 procedure SS_Allocate
97 (Address : out System.Address;
98 Storage_Size : SSE.Storage_Count)
99 is
100 Max_Align : constant Mark_Id := Mark_Id (Standard'Maximum_Alignment);
101 Max_Size : constant Mark_Id :=
102 ((Mark_Id (Storage_Size) + Max_Align - 1) / Max_Align)
103 * Max_Align;
104 Sec_Stack : constant Stack_Ptr := Get_Sec_Stack;
105
106 begin
107 if Sec_Stack.Top + Max_Size > Sec_Stack.Last then
108 raise Storage_Error;
109 end if;
110
111 Address := Sec_Stack.Mem (Sec_Stack.Top)'Address;
112 Sec_Stack.Top := Sec_Stack.Top + Max_Size;
113 end SS_Allocate;
114
115 -------------
116 -- SS_Init --
117 -------------
118
119 procedure SS_Init
120 (Stk : System.Address;
121 Size : Natural := Default_Secondary_Stack_Size)
122 is
123 Stack : constant Stack_Ptr := From_Addr (Stk);
124
125 begin
126 pragma Assert (Size >= 2 * Mark_Id'Max_Size_In_Storage_Elements);
127 pragma Assert
128 (Stk mod Standard'Maximum_Alignment = SSE.Storage_Offset'(0));
129
130 Stack.Top := Stack.Mem'First;
131 Stack.Last := Mark_Id (Size) - 2 * Mark_Id'Max_Size_In_Storage_Elements;
132 end SS_Init;
133
134 -------------
135 -- SS_Mark --
136 -------------
137
138 function SS_Mark return Mark_Id is
139 begin
140 return Get_Sec_Stack.Top;
141 end SS_Mark;
142
143 ----------------
144 -- SS_Release --
145 ----------------
146
147 procedure SS_Release (M : Mark_Id) is
148 begin
149 Get_Sec_Stack.Top := M;
150 end SS_Release;
151
152 end System.Secondary_Stack;