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------------------------------------------------------------------------------
-- --
-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . T A S K _ P R I M I T I V E S --
-- --
-- S p e c --
-- --
-- Copyright (C) 1991-2001, Florida State University --
-- --
-- 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, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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. It is --
-- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
-- State University (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
-- RT_GNU/Linux version
pragma Polling (Off);
-- Turn off polling, we do not want ATC polling to take place during
-- tasking operations. It causes infinite loops and other problems.
with System.OS_Interface;
package System.Task_Primitives is
type Lock is limited private;
-- Used for implementation of protected objects.
type Lock_Ptr is limited private;
type RTS_Lock is limited private;
-- Used inside the runtime system. The difference between Lock and the
-- RTS_Lock is that the later one serves only as a semaphore so that do
-- not check for ceiling violations.
type RTS_Lock_Ptr is limited private;
type Task_Body_Access is access procedure;
-- Pointer to the task body's entry point (or possibly a wrapper
-- declared local to the GNARL).
type Private_Data is limited private;
-- Any information that the GNULLI needs maintained on a per-task
-- basis. A component of this type is guaranteed to be included
-- in the Ada_Task_Control_Block.
private
type RT_GNU_Linux_Lock is record
Ceiling_Priority : System.Any_Priority;
Pre_Locking_Priority : System.Any_Priority;
-- Used to store the task's active priority before it
-- acquires the lock
Owner : System.Address;
-- This is really a Task_ID, but we can't use that type
-- here because this System.Tasking is "with"
-- the current package -- a circularity.
end record;
type Lock is new RT_GNU_Linux_Lock;
type RTS_Lock is new RT_GNU_Linux_Lock;
type RTS_Lock_Ptr is access all RTS_Lock;
type Lock_Ptr is access all Lock;
type Private_Data is record
Stack : System.Address;
-- A stack space needed for the task. the space is allocated
-- when the task is being created and is deallocated when
-- the TCB for the task is finalized
Uses_Fp : Integer;
-- A flag to indicate whether the task is going to use floating-
-- point unit. It's set to 1, indicating FP unit is always going
-- to be used. The reason is that it is in this private record and
-- necessary operation has to be provided for a user to call so as
-- to change its value
Magic : Integer;
-- A special value is going to be stored in it when a task is
-- created. The value is RT_TASK_MAGIC (16#754d2774#) as declared
-- in System.OS_Interface
State : System.OS_Interface.Rt_Task_States;
-- Shows whether the task is RT_TASK_READY, RT_TASK_DELAYED or
-- RT_TASK_DORMANT to support suspend, wait, wakeup.
Stack_Bottom : System.Address;
Active_Priority : System.Any_Priority;
-- Active priority of the task
Period : System.OS_Interface.RTIME;
-- Intended originally to store the period of the task, but not used
-- in the current implementation
Resume_Time : System.OS_Interface.RTIME;
-- Store the time the task has to be awakened
Next : System.Address;
-- This really is a Task_ID, used to link the Available_TCBs.
Succ : System.Address;
pragma Volatile (Succ);
Pred : System.Address;
pragma Volatile (Pred);
-- These really are Task_ID, used to implement a circular doubly
-- linked list for task queue
L : aliased RTS_Lock;
Outer_Lock : RTS_Lock_Ptr := null;
-- Used to track which Lock the task is holding is the outermost
-- one in order to implement priority setting and inheritance
end record;
-- ???? May need to use pragma Atomic or Volatile on some
-- components; may also need to specify aliased for some.
end System.Task_Primitives;
|
