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) 1992-2008, 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 with System
.Parameters
;
51 package System
.Tasking
.Restricted
.Stages
is
52 pragma Elaborate_Body
;
54 ---------------------------------
55 -- Compiler Interface (GNARLI) --
56 ---------------------------------
58 -- The compiler will expand in the GNAT tree the following construct:
60 -- task type T (Discr : Integer);
63 -- ...declarations, possibly some controlled...
72 -- task type t (discr : integer);
73 -- tE : aliased boolean := false;
74 -- tZ : size_type := unspecified_size;
76 -- type tV (discr : integer) is limited record
77 -- _task_id : task_id;
78 -- _atcb : aliased system__tasking__ada_task_control_block (0);
81 -- procedure tB (_task : access tV);
83 -- procedure tVIP (_init : in out tV; _master : master_id;
84 -- _chain : in out activation_chain; _task_name : in string;
85 -- discr : integer) is
87 -- _init.discr := discr;
88 -- _init._task_id := null;
89 -- system__tasking__ada_task_control_blockIP (_init._atcb, 0);
90 -- _init._task_id := _init._atcb'unchecked_access;
91 -- create_restricted_task (unspecified_priority, tZ,
92 -- unspecified_task_info, task_procedure_access!(tB'address),
93 -- _init'address, tE'unchecked_access, _chain, _task_name, _init.
98 -- _chain : aliased activation_chain;
99 -- activation_chainIP (_chain);
101 -- procedure tB (_task : access tV) is
102 -- discr : integer renames _task.discr;
104 -- procedure _clean is
106 -- complete_restricted_task;
107 -- finalize_list (F14b);
112 -- ...declarations...
113 -- complete_restricted_activation;
122 -- t1S : constant String := "t1";
123 -- tIP (t1, 3, _chain, t1S, 1);
125 -- activate_restricted_tasks (_chain'unchecked_access);
127 procedure Create_Restricted_Task
129 Stack_Address
: System
.Address
;
130 Size
: System
.Parameters
.Size_Type
;
131 Task_Info
: System
.Task_Info
.Task_Info_Type
;
132 State
: Task_Procedure_Access
;
133 Discriminants
: System
.Address
;
134 Elaborated
: Access_Boolean
;
135 Chain
: in out Activation_Chain
;
137 Created_Task
: Task_Id
);
138 -- Compiler interface only. Do not call from within the RTS.
139 -- This must be called to create a new task.
141 -- Priority is the task's priority (assumed to be in the
142 -- System.Any_Priority'Range)
144 -- Stack_Address is the start address of the stack associated to the task,
145 -- in case it has been preallocated by the compiler; it is equal to
146 -- Null_Address when the stack needs to be allocated by the underlying
149 -- Size is the stack size of the task to create
151 -- Task_Info is the task info associated with the created task, or
152 -- Unspecified_Task_Info if none.
154 -- State is the compiler generated task's procedure body
156 -- Discriminants is a pointer to a limited record whose discriminants are
157 -- those of the task to create. This parameter should be passed as the
158 -- single argument to State.
160 -- Elaborated is a pointer to a Boolean that must be set to true on exit
161 -- if the task could be successfully elaborated.
163 -- Chain is a linked list of task that needs to be created. On exit,
164 -- Created_Task.Activation_Link will be Chain.T_ID, and Chain.T_ID will be
165 -- Created_Task (the created task will be linked at the front of Chain).
167 -- Task_Image is a string created by the compiler that the run time can
168 -- store to ease the debugging and the Ada.Task_Identification facility.
170 -- Created_Task is the resulting task.
172 -- This procedure can raise Storage_Error if the task creation fails
174 procedure Activate_Restricted_Tasks
175 (Chain_Access
: Activation_Chain_Access
);
176 -- Compiler interface only. Do not call from within the RTS.
177 -- This must be called by the creator of a chain of one or more new tasks,
178 -- to activate them. The chain is a linked list that up to this point is
179 -- only known to the task that created them, though the individual tasks
180 -- are already in the All_Tasks_List.
182 -- The compiler builds the chain in LIFO order (as a stack). Another
183 -- version of this procedure had code to reverse the chain, so as to
184 -- activate the tasks in the order of declaration. This might be nice, but
185 -- it is not needed if priority-based scheduling is supported, since all
186 -- the activated tasks synchronize on the activators lock before they start
187 -- activating and so they should start activating in priority order.
189 procedure Complete_Restricted_Activation
;
190 -- Compiler interface only. Do not call from within the RTS. This should be
191 -- called from the task body at the end of the elaboration code for its
192 -- declarative part. Decrement the count of tasks to be activated by the
193 -- activator and wake it up so it can check to see if all tasks have been
194 -- activated. Except for the environment task, which should never call this
195 -- procedure, T.Activator should only be null iff T has completed
198 procedure Complete_Restricted_Task
;
199 -- Compiler interface only. Do not call from within the RTS. This should be
200 -- called from an implicit at-end handler associated with the task body,
201 -- when it completes. From this point, the current task will become not
202 -- callable. If the current task have not completed activation, this should
203 -- be done now in order to wake up the activator (the environment task).
205 function Restricted_Terminated
(T
: Task_Id
) return Boolean;
206 -- Compiler interface only. Do not call from within the RTS. This is called
207 -- by the compiler to implement the 'Terminated attribute.
213 -- restricted_terminated (t1._task_id)
215 procedure Finalize_Global_Tasks
;
216 -- This is needed to support the compiler interface; it will only be called
217 -- by the Environment task in the binder generated file (by adafinal).
218 -- Instead, it will cause the Environment to block forever, since none of
219 -- the dependent tasks are expected to terminate
221 end System
.Tasking
.Restricted
.Stages
;