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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;