1 ------------------------------------------------------------------------------
3 -- GNAT 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) 1992-2006, 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, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, 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 task,
148 -- in case it has been preallocated by the compiler; it is equal to
149 -- Null_Address when the stack needs to be allocated by the underlying
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 are
160 -- those of the task to create. This parameter should be passed as the
161 -- 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 will be
168 -- Created_Task (the created task will be linked at the front of Chain).
170 -- Task_Image is a string created by the compiler that the run time can
171 -- store to ease the debugging and the Ada.Task_Identification facility.
173 -- Created_Task is the resulting task.
175 -- This procedure can raise Storage_Error if the task creation fails
177 procedure Activate_Restricted_Tasks
178 (Chain_Access : Activation_Chain_Access);
179 -- Compiler interface only. Do not call from within the RTS.
180 -- This must be called by the creator of a chain of one or more new tasks,
181 -- to activate them. The chain is a linked list that up to this point is
182 -- only known to the task that created them, though the individual tasks
183 -- are already in the All_Tasks_List.
185 -- The compiler builds the chain in LIFO order (as a stack). Another
186 -- version of this procedure had code to reverse the chain, so as to
187 -- activate the tasks in the order of declaration. This might be nice, but
188 -- it is not needed if priority-based scheduling is supported, since all
189 -- the activated tasks synchronize on the activators lock before they start
190 -- activating and so they should start activating in priority order.
192 procedure Complete_Restricted_Activation;
193 -- Compiler interface only. Do not call from within the RTS. This should be
194 -- called from the task body at the end of the elaboration code for its
195 -- declarative part. Decrement the count of tasks to be activated by the
196 -- activator and wake it up so it can check to see if all tasks have been
197 -- activated. Except for the environment task, which should never call this
198 -- procedure, T.Activator should only be null iff T has completed
201 procedure Complete_Restricted_Task;
202 -- Compiler interface only. Do not call from within the RTS. This should be
203 -- called from an implicit at-end handler associated with the task body,
204 -- when it completes. From this point, the current task will become not
205 -- callable. If the current task have not completed activation, this should
206 -- be done now in order to wake up the activator (the environment task).
208 function Restricted_Terminated (T : Task_Id) return Boolean;
209 -- Compiler interface only. Do not call from within the RTS. This is called
210 -- by the compiler to implement the 'Terminated attribute.
216 -- restricted_terminated (t1._task_id)
218 procedure Finalize_Global_Tasks;
219 -- This is needed to support the compiler interface; it will only be called
220 -- by the Environment task in the binder generated file (by adafinal).
221 -- Instead, it will cause the Environment to block forever, since none of
222 -- the dependent tasks are expected to terminate
224 end System.Tasking.Restricted.Stages;