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------------------------------------------------------------------------------
-- --
-- GNAT 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) 1992-2009, 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 3, or (at your option) any later ver- --
-- sion. GNAT 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. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
------------------------------------------------------------------------------
-- 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;
with System.Parameters;
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;
-- _atcb : aliased system__tasking__ada_task_control_block (0);
-- end record;
-- procedure tB (_task : access tV);
-- freeze tV [
-- procedure tVIP (_init : in out tV; _master : master_id;
-- _chain : in out activation_chain; _task_name : in string;
-- discr : integer) is
-- begin
-- _init.discr := discr;
-- _init._task_id := null;
-- system__tasking__ada_task_control_blockIP (_init._atcb, 0);
-- _init._task_id := _init._atcb'unchecked_access;
-- create_restricted_task (unspecified_priority, tZ,
-- unspecified_task_info, task_procedure_access!(tB'address),
-- _init'address, tE'unchecked_access, _chain, _task_name, _init.
-- _task_id);
-- return;
-- end tVIP;
-- _chain : aliased activation_chain;
-- activation_chainIP (_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);
-- t1S : constant String := "t1";
-- tIP (t1, 3, _chain, t1S, 1);
-- activate_restricted_tasks (_chain'unchecked_access);
procedure Create_Restricted_Task
(Priority : Integer;
Stack_Address : System.Address;
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 : String;
Created_Task : 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)
--
-- Stack_Address is the start address of the stack associated to the task,
-- in case it has been preallocated by the compiler; it is equal to
-- Null_Address when the stack needs to be allocated by the underlying
-- operating system.
--
-- 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 (the created task will be linked at the front of Chain).
--
-- Task_Image is 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 fails
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;
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