1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
------------------------------------------------------------------------------
-- --
-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . T A S K I N G . R E S T R I C T E D . S T A G E S --
-- --
-- S p e c --
-- --
-- --
-- Copyright (C) 1992-1999, Free Software Foundation, Inc. --
-- --
-- GNARL is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNARL; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. It is --
-- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
-- State University (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
-- This is a simplified version of the System.Tasking.Stages package,
-- intended to be used in a restricted run time.
-- This package represents the high level tasking interface used by the
-- compiler to expand Ada 95 tasking constructs into simpler run time calls
-- (aka GNARLI, GNU Ada Run-time Library Interface)
-- Note: the compiler generates direct calls to this interface, via Rtsfind.
-- Any changes to this interface may require corresponding compiler changes
-- in exp_ch9.adb and possibly exp_ch7.adb
-- The restricted GNARLI is also composed of System.Protected_Objects and
-- System.Protected_Objects.Single_Entry
with System.Task_Info;
-- used for Task_Info_Type
with System.Parameters;
-- used for Size_Type
package System.Tasking.Restricted.Stages is
pragma Elaborate_Body;
---------------------------------
-- Compiler Interface (GNARLI) --
---------------------------------
-- The compiler will expand in the GNAT tree the following construct:
--
-- task type T (Discr : Integer);
--
-- task body T is
-- ...declarations, possibly some controlled...
-- begin
-- ...B...;
-- end T;
--
-- T1 : T (1);
--
-- as follows:
--
-- task type t (discr : integer);
-- tE : aliased boolean := false;
-- tZ : size_type := unspecified_size;
-- type tV (discr : integer) is limited record
-- _task_id : task_id;
-- end record;
-- procedure tB (_task : access tV);
-- freeze tV [
-- procedure _init_proc (_init : in out tV; _master : master_id;
-- _chain : in out activation_chain; _task_id : in task_image_type;
-- discr : integer) is
-- begin
-- _init.discr := discr;
-- _init._task_id := null;
-- create_restricted_task (unspecified_priority, tZ,
-- unspecified_task_info, task_procedure_access!(tB'address),
-- _init'address, tE'unchecked_access, _chain, _task_id, _init.
-- _task_id);
-- return;
-- end _init_proc;
-- ]
--
-- _chain : aliased activation_chain;
-- _init_proc (_chain);
--
-- procedure tB (_task : access tV) is
-- discr : integer renames _task.discr;
--
-- procedure _clean is
-- begin
-- complete_restricted_task;
-- finalize_list (F14b);
-- return;
-- end _clean;
-- begin
-- ...declarations...
-- complete_restricted_activation;
-- ...B...;
-- return;
-- at end
-- _clean;
-- end tB;
--
-- tE := true;
-- t1 : t (1);
-- t1I : task_image_type := new string'"t1";
-- _init_proc (t1, 3, _chain, t1I, 1);
--
-- activate_restricted_tasks (_chain'unchecked_access);
procedure Create_Restricted_Task
(Priority : Integer;
Size : System.Parameters.Size_Type;
Task_Info : System.Task_Info.Task_Info_Type;
State : Task_Procedure_Access;
Discriminants : System.Address;
Elaborated : Access_Boolean;
Chain : in out Activation_Chain;
Task_Image : System.Task_Info.Task_Image_Type;
Created_Task : out Task_ID);
-- Compiler interface only. Do not call from within the RTS.
-- This must be called to create a new task.
--
-- Priority is the task's priority (assumed to be in the
-- System.Any_Priority'Range)
-- Size is the stack size of the task to create
-- Task_Info is the task info associated with the created task, or
-- Unspecified_Task_Info if none.
-- State is the compiler generated task's procedure body
-- Discriminants is a pointer to a limited record whose discriminants
-- are those of the task to create. This parameter should be passed as
-- the single argument to State.
-- Elaborated is a pointer to a Boolean that must be set to true on exit
-- if the task could be successfully elaborated.
-- Chain is a linked list of task that needs to be created. On exit,
-- Created_Task.Activation_Link will be Chain.T_ID, and Chain.T_ID
-- will be Created_Task (e.g the created task will be linked at the front
-- of Chain).
-- Task_Image is a pointer to a string created by the compiler that the
-- run time can store to ease the debugging and the
-- Ada.Task_Identification facility.
-- Created_Task is the resulting task.
--
-- This procedure can raise Storage_Error if the task creation failed.
procedure Activate_Restricted_Tasks
(Chain_Access : Activation_Chain_Access);
-- Compiler interface only. Do not call from within the RTS.
-- This must be called by the creator of a chain of one or more new tasks,
-- to activate them. The chain is a linked list that up to this point is
-- only known to the task that created them, though the individual tasks
-- are already in the All_Tasks_List.
--
-- The compiler builds the chain in LIFO order (as a stack). Another
-- version of this procedure had code to reverse the chain, so as to
-- activate the tasks in the order of declaration. This might be nice, but
-- it is not needed if priority-based scheduling is supported, since all
-- the activated tasks synchronize on the activators lock before they
-- start activating and so they should start activating in priority order.
procedure Complete_Restricted_Activation;
-- Compiler interface only. Do not call from within the RTS.
-- This should be called from the task body at the end of
-- the elaboration code for its declarative part.
-- Decrement the count of tasks to be activated by the activator and
-- wake it up so it can check to see if all tasks have been activated.
-- Except for the environment task, which should never call this procedure,
-- T.Activator should only be null iff T has completed activation.
procedure Complete_Restricted_Task;
-- Compiler interface only. Do not call from within the RTS.
-- This should be called from an implicit at-end handler
-- associated with the task body, when it completes.
-- From this point, the current task will become not callable.
-- If the current task have not completed activation, this should be done
-- now in order to wake up the activator (the environment task).
function Restricted_Terminated (T : Task_ID) return Boolean;
-- Compiler interface only. Do not call from within the RTS.
-- This is called by the compiler to implement the 'Terminated attribute.
--
-- source code:
-- T1'Terminated
--
-- code expansion:
-- restricted_terminated (t1._task_id)
procedure Finalize_Global_Tasks;
-- This is needed to support the compiler interface; it will only be called
-- by the Environment task in the binder generated file (by adafinal).
-- Instead, it will cause the Environment to block forever, since none of
-- the dependent tasks are expected to terminate
end System.Tasking.Restricted.Stages;
|
