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1 706 jeremybenn
------------------------------------------------------------------------------
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--                                                                          --
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--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
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--                                                                          --
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--     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      --
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--                                                                          --
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--                                  S p e c                                 --
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--                                                                          --
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--          Copyright (C) 1992-2010, Free Software Foundation, Inc.         --
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--                                                                          --
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-- GNARL is free software; you can  redistribute it  and/or modify it under --
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-- terms of the  GNU General Public License as published  by the Free Soft- --
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-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
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-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
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--                                                                          --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception,   --
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-- version 3.1, as published by the Free Software Foundation.               --
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--                                                                          --
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-- You should have received a copy of the GNU General Public License and    --
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-- a copy of the GCC Runtime Library Exception along with this program;     --
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-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
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-- <http://www.gnu.org/licenses/>.                                          --
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--                                                                          --
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-- GNARL was developed by the GNARL team at Florida State University.       --
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-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
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--                                                                          --
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------------------------------------------------------------------------------
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--  This is a simplified version of the System.Tasking.Stages package,
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--  intended to be used in a restricted run time.
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--  This package represents the high level tasking interface used by the
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--  compiler to expand Ada 95 tasking constructs into simpler run time calls
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--  (aka GNARLI, GNU Ada Run-time Library Interface)
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--  Note: the compiler generates direct calls to this interface, via Rtsfind.
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--  Any changes to this interface may require corresponding compiler changes
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--  in exp_ch9.adb and possibly exp_ch7.adb
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--  The restricted GNARLI is also composed of System.Protected_Objects and
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--  System.Protected_Objects.Single_Entry
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with System.Task_Info;
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with System.Parameters;
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package System.Tasking.Restricted.Stages is
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   pragma Elaborate_Body;
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   ---------------------------------
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   -- Compiler Interface (GNARLI) --
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   ---------------------------------
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   --  The compiler will expand in the GNAT tree the following construct:
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   --   task type T (Discr : Integer);
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   --   task body T is
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   --      ...declarations, possibly some controlled...
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   --   begin
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   --      ...B...;
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   --   end T;
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   --   T1 : T (1);
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   --  as follows:
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   --   task type t (discr : integer);
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   --   tE : aliased boolean := false;
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   --   tZ : size_type := unspecified_size;
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   --   type tV (discr : integer) is limited record
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   --      _task_id : task_id;
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   --      _atcb : aliased system__tasking__ada_task_control_block (0);
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   --   end record;
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   --   procedure tB (_task : access tV);
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   --   freeze tV [
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   --      procedure tVIP (_init : in out tV; _master : master_id;
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   --        _chain : in out activation_chain; _task_name : in string;
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   --        discr : integer) is
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   --      begin
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   --         _init.discr := discr;
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   --         _init._task_id := null;
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   --         system__tasking__ada_task_control_blockIP (_init._atcb, 0);
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   --         _init._task_id := _init._atcb'unchecked_access;
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   --         create_restricted_task (unspecified_priority, tZ,
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   --           unspecified_task_info, unspecified_cpu,
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   --           task_procedure_access!(tB'address), _init'address,
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   --           tE'unchecked_access, _chain, _task_name, _init._task_id);
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   --         return;
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   --      end tVIP;
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   --   _chain : aliased activation_chain;
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   --   activation_chainIP (_chain);
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   --   procedure tB (_task : access tV) is
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   --      discr : integer renames _task.discr;
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   --      procedure _clean is
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   --      begin
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   --         complete_restricted_task;
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   --         finalize_list (F14b);
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   --         return;
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   --      end _clean;
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   --   begin
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   --      ...declarations...
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   --      complete_restricted_activation;
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   --      ...B...;
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   --      return;
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   --   at end
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   --      _clean;
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   --   end tB;
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   --   tE := true;
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   --   t1 : t (1);
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   --   t1S : constant String := "t1";
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   --   tIP (t1, 3, _chain, t1S, 1);
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   --   activate_restricted_tasks (_chain'unchecked_access);
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   procedure Create_Restricted_Task
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     (Priority      : Integer;
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      Stack_Address : System.Address;
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      Size          : System.Parameters.Size_Type;
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      Task_Info     : System.Task_Info.Task_Info_Type;
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      CPU           : Integer;
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      State         : Task_Procedure_Access;
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      Discriminants : System.Address;
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      Elaborated    : Access_Boolean;
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      Chain         : in out Activation_Chain;
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      Task_Image    : String;
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      Created_Task  : Task_Id);
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   --  Compiler interface only. Do not call from within the RTS.
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   --  This must be called to create a new task.
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   --
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   --  Priority is the task's priority (assumed to be in the
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   --  System.Any_Priority'Range)
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   --
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   --  Stack_Address is the start address of the stack associated to the task,
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   --  in case it has been preallocated by the compiler; it is equal to
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   --  Null_Address when the stack needs to be allocated by the underlying
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   --  operating system.
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   --
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   --  Size is the stack size of the task to create
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   --
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   --  Task_Info is the task info associated with the created task, or
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   --  Unspecified_Task_Info if none.
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   --
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   --  CPU is the task affinity. We pass it as an Integer to avoid an explicit
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   --   dependency from System.Multiprocessors when not needed. Static range
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   --   checks are performed when analyzing the pragma, and dynamic ones are
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   --   performed before setting the affinity at run time.
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   --
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   --  State is the compiler generated task's procedure body
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   --
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   --  Discriminants is a pointer to a limited record whose discriminants are
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   --  those of the task to create. This parameter should be passed as the
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   --  single argument to State.
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   --
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   --  Elaborated is a pointer to a Boolean that must be set to true on exit
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   --  if the task could be successfully elaborated.
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   --
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   --  Chain is a linked list of task that needs to be created. On exit,
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   --  Created_Task.Activation_Link will be Chain.T_ID, and Chain.T_ID will be
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   --  Created_Task (the created task will be linked at the front of Chain).
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   --
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   --  Task_Image is a string created by the compiler that the run time can
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   --  store to ease the debugging and the Ada.Task_Identification facility.
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   --
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   --  Created_Task is the resulting task.
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   --
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   --  This procedure can raise Storage_Error if the task creation fails
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   procedure Activate_Restricted_Tasks
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     (Chain_Access : Activation_Chain_Access);
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   --  Compiler interface only. Do not call from within the RTS.
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   --  This must be called by the creator of a chain of one or more new tasks,
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   --  to activate them. The chain is a linked list that up to this point is
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   --  only known to the task that created them, though the individual tasks
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   --  are already in the All_Tasks_List.
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   --
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   --  The compiler builds the chain in LIFO order (as a stack). Another
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   --  version of this procedure had code to reverse the chain, so as to
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   --  activate the tasks in the order of declaration. This might be nice, but
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   --  it is not needed if priority-based scheduling is supported, since all
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   --  the activated tasks synchronize on the activators lock before they start
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   --  activating and so they should start activating in priority order.
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   procedure Complete_Restricted_Activation;
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   --  Compiler interface only. Do not call from within the RTS. This should be
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   --  called from the task body at the end of the elaboration code for its
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   --  declarative part. Decrement the count of tasks to be activated by the
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   --  activator and wake it up so it can check to see if all tasks have been
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   --  activated. Except for the environment task, which should never call this
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   --  procedure, T.Activator should only be null iff T has completed
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   --  activation.
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   procedure Complete_Restricted_Task;
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   --  Compiler interface only. Do not call from within the RTS. This should be
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   --  called from an implicit at-end handler associated with the task body,
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   --  when it completes. From this point, the current task will become not
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   --  callable. If the current task have not completed activation, this should
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   --  be done now in order to wake up the activator (the environment task).
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   function Restricted_Terminated (T : Task_Id) return Boolean;
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   --  Compiler interface only. Do not call from within the RTS. This is called
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   --  by the compiler to implement the 'Terminated attribute.
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   --
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   --  source code:
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   --     T1'Terminated
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   --
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   --  code expansion:
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   --     restricted_terminated (t1._task_id)
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   procedure Finalize_Global_Tasks;
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   --  This is needed to support the compiler interface; it will only be called
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   --  by the Environment task in the binder generated file (by adafinal).
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   --  Instead, it will cause the Environment to block forever, since none of
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   --  the dependent tasks are expected to terminate
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end System.Tasking.Restricted.Stages;

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