------------------------------------------------------------------------------ -- -- -- 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) 1992-2005, 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 2, or (at your option) any later ver- -- -- sion. GNARL 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. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNARL; see file COPYING. If not, write -- -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- -- Boston, MA 02110-1301, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- 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; -- used for Task_Info_Type with System.Parameters; -- used for Size_Type 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 sucessfully 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 (e.g 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;