1 ------------------------------------------------------------------------------
3 -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- 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 --
9 -- Copyright (C) 1992-2004, Free Software Foundation, Inc. --
11 -- GNARL 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 2, or (at your option) any later ver- --
14 -- sion. GNARL 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. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNARL; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNARL was developed by the GNARL team at Florida State University. --
30 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
32 ------------------------------------------------------------------------------
34 -- This is a simplified version of the System.Tasking.Stages package,
35 -- intended to be used in a restricted run time.
37 -- This package represents the high level tasking interface used by the
38 -- compiler to expand Ada 95 tasking constructs into simpler run time calls
39 -- (aka GNARLI, GNU Ada Run-time Library Interface)
41 -- Note: the compiler generates direct calls to this interface, via Rtsfind.
42 -- Any changes to this interface may require corresponding compiler changes
43 -- in exp_ch9.adb and possibly exp_ch7.adb
45 -- The restricted GNARLI is also composed of System.Protected_Objects and
46 -- System.Protected_Objects.Single_Entry
48 with System
.Task_Info
;
49 -- used for Task_Info_Type
51 with System
.Parameters
;
54 package System
.Tasking
.Restricted
.Stages
is
55 pragma Elaborate_Body
;
57 ---------------------------------
58 -- Compiler Interface (GNARLI) --
59 ---------------------------------
61 -- The compiler will expand in the GNAT tree the following construct:
63 -- task type T (Discr : Integer);
66 -- ...declarations, possibly some controlled...
75 -- task type t (discr : integer);
76 -- tE : aliased boolean := false;
77 -- tZ : size_type := unspecified_size;
79 -- type tV (discr : integer) is limited record
80 -- _task_id : task_id;
81 -- _atcb : aliased system__tasking__ada_task_control_block (0);
84 -- procedure tB (_task : access tV);
86 -- procedure tVIP (_init : in out tV; _master : master_id;
87 -- _chain : in out activation_chain; _task_name : in string;
88 -- discr : integer) is
90 -- _init.discr := discr;
91 -- _init._task_id := null;
92 -- system__tasking__ada_task_control_blockIP (_init._atcb, 0);
93 -- _init._task_id := _init._atcb'unchecked_access;
94 -- create_restricted_task (unspecified_priority, tZ,
95 -- unspecified_task_info, task_procedure_access!(tB'address),
96 -- _init'address, tE'unchecked_access, _chain, _task_name, _init.
101 -- _chain : aliased activation_chain;
102 -- activation_chainIP (_chain);
104 -- procedure tB (_task : access tV) is
105 -- discr : integer renames _task.discr;
107 -- procedure _clean is
109 -- complete_restricted_task;
110 -- finalize_list (F14b);
115 -- ...declarations...
116 -- complete_restricted_activation;
125 -- t1S : constant String := "t1";
126 -- tIP (t1, 3, _chain, t1S, 1);
128 -- activate_restricted_tasks (_chain'unchecked_access);
130 procedure Create_Restricted_Task
132 Stack_Address
: System
.Address
;
133 Size
: System
.Parameters
.Size_Type
;
134 Task_Info
: System
.Task_Info
.Task_Info_Type
;
135 State
: Task_Procedure_Access
;
136 Discriminants
: System
.Address
;
137 Elaborated
: Access_Boolean
;
138 Chain
: in out Activation_Chain
;
140 Created_Task
: Task_Id
);
141 -- Compiler interface only. Do not call from within the RTS.
142 -- This must be called to create a new task.
144 -- Priority is the task's priority (assumed to be in the
145 -- System.Any_Priority'Range)
147 -- Stack_Address is the start address of the stack associated to the
148 -- task, in case it has been preallocated by the compiler; it is equal
149 -- to Null_Address when the stack needs to be allocated by the
150 -- underlying operating system.
152 -- Size is the stack size of the task to create
154 -- Task_Info is the task info associated with the created task, or
155 -- Unspecified_Task_Info if none.
157 -- State is the compiler generated task's procedure body
159 -- Discriminants is a pointer to a limited record whose discriminants
160 -- are those of the task to create. This parameter should be passed as
161 -- the single argument to State.
163 -- Elaborated is a pointer to a Boolean that must be set to true on exit
164 -- if the task could be sucessfully elaborated.
166 -- Chain is a linked list of task that needs to be created. On exit,
167 -- Created_Task.Activation_Link will be Chain.T_ID, and Chain.T_ID
168 -- will be Created_Task (e.g the created task will be linked at the front
171 -- Task_Image is a string created by the compiler that the
172 -- run time can store to ease the debugging and the
173 -- Ada.Task_Identification facility.
175 -- Created_Task is the resulting task.
177 -- This procedure can raise Storage_Error if the task creation fails
179 procedure Activate_Restricted_Tasks
180 (Chain_Access
: Activation_Chain_Access
);
181 -- Compiler interface only. Do not call from within the RTS.
182 -- This must be called by the creator of a chain of one or more new tasks,
183 -- to activate them. The chain is a linked list that up to this point is
184 -- only known to the task that created them, though the individual tasks
185 -- are already in the All_Tasks_List.
187 -- The compiler builds the chain in LIFO order (as a stack). Another
188 -- version of this procedure had code to reverse the chain, so as to
189 -- activate the tasks in the order of declaration. This might be nice, but
190 -- it is not needed if priority-based scheduling is supported, since all
191 -- the activated tasks synchronize on the activators lock before they
192 -- start activating and so they should start activating in priority order.
194 procedure Complete_Restricted_Activation
;
195 -- Compiler interface only. Do not call from within the RTS.
196 -- This should be called from the task body at the end of
197 -- the elaboration code for its declarative part.
198 -- Decrement the count of tasks to be activated by the activator and
199 -- wake it up so it can check to see if all tasks have been activated.
200 -- Except for the environment task, which should never call this procedure,
201 -- T.Activator should only be null iff T has completed activation.
203 procedure Complete_Restricted_Task
;
204 -- Compiler interface only. Do not call from within the RTS.
205 -- This should be called from an implicit at-end handler
206 -- associated with the task body, when it completes.
207 -- From this point, the current task will become not callable.
208 -- If the current task have not completed activation, this should be done
209 -- now in order to wake up the activator (the environment task).
211 function Restricted_Terminated
(T
: Task_Id
) return Boolean;
212 -- Compiler interface only. Do not call from within the RTS.
213 -- This is called by the compiler to implement the 'Terminated attribute.
219 -- restricted_terminated (t1._task_id)
221 procedure Finalize_Global_Tasks
;
222 -- This is needed to support the compiler interface; it will only be called
223 -- by the Environment task in the binder generated file (by adafinal).
224 -- Instead, it will cause the Environment to block forever, since none of
225 -- the dependent tasks are expected to terminate
227 end System
.Tasking
.Restricted
.Stages
;