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--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--                         G N A T . T H R E A D S                          --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--                     Copyright (C) 1998-2007, AdaCore                     --

--                                                                          --

-- GNAT 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.  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.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT;  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.                                      --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

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--  This package provides facilities for creation or registration of foreign

--  threads for use as Ada tasks. In order to execute general Ada code, the

--  run-time system must know about all tasks. This package allows foreign

--  code, e.g. a C program, to create a thread that the Ada run-time knows

--  about, or to register the current thread.

--  For some implementations of GNAT Pro, the registration of foreign threads

--  is automatic. However, in such implementations, if the Ada program has no

--  tasks at all and no tasking constructs other than delay, then by default

--  the non-tasking version of the Ada run-time will be loaded. If foreign

--  threads are present, it is important to ensure that the tasking version

--  of the Ada run time is loaded. This may be achieved by adding "with

--  GNAT.Threads" to any unit in the partition.

with System;

with Ada.Task_Identification;

package GNAT.Threads is

   type Void_Ptr is access all Integer;

   function Create_Thread

     (Code : System.Address;  -- pointer

      Parm : Void_Ptr;        -- pointer

      Size : Natural;         -- int

      Prio : Integer)         -- int

      return System.Address;

   pragma Export (C, Create_Thread, "__gnat_create_thread");

   --  Creates a thread with the given (Size) stack size in bytes, and

   --  the given (Prio) priority. The task will execute a call to the

   --  procedure whose address is given by Code. This procedure has

   --  the prototype

   --

   --    void thread_code (void *id, void *parm);

   --

   --  where id is the id of the created task, and parm is the parameter

   --  passed to Create_Thread. The called procedure is the body of the

   --  code for the task, the task will be automatically terminated when

   --  the procedure returns.

   --

   --  This function returns the Ada Id of the created task that can then be

   --  used as a parameter to the procedures below.

   --

   --  C declaration:

   --

   --  extern void *__gnat_create_thread

   --    (void (*code)(void *, void *), void *parm, int size, int prio);

   function Register_Thread return System.Address;

   pragma Export (C, Register_Thread, "__gnat_register_thread");

   --  Create an Ada task Id for the current thread if needed.

   --  If the thread could not be registered, System.Null_Address is returned.

   --

   --  This function returns the Ada Id of the current task that can then be

   --  used as a parameter to the procedures below.

   --

   --  C declaration:

   --

   --  extern void *__gnat_register_thread ();

   --

   --  Here is a typical usage of the Register/Unregister_Thread procedures:

   --

   --  void thread_body ()

   --  {

   --    void *task_id = __gnat_register_thread ();

   --    ... thread body ...

   --    __gnat_unregister_thread ();

   --  }

   procedure Unregister_Thread;

   pragma Export (C, Unregister_Thread, "__gnat_unregister_thread");

   --  Unregister the current task from the GNAT run time and destroy the

   --  memory allocated for its task id.

   --

   --  C declaration:

   --

   --  extern void __gnat_unregister_thread ();

   procedure Unregister_Thread_Id (Thread : System.Address);

   pragma Export (C, Unregister_Thread_Id, "__gnat_unregister_thread_id");

   --  Unregister the task associated with Thread from the GNAT run time and

   --  destroy the memory allocated for its task id.

   --  If no task id is associated with Thread, do nothing.

   --

   --  C declaration:

   --

   --  extern void __gnat_unregister_thread_id (pthread_t *thread);

   procedure Destroy_Thread (Id : System.Address);

   pragma Export (C, Destroy_Thread, "__gnat_destroy_thread");

   --  This procedure may be used to prematurely abort the created thread.

   --  The value Id is the value that was passed to the thread code procedure

   --  at activation time.

   --

   --  C declaration:

   --

   --  extern void __gnat_destroy_thread (void *id);

   procedure Get_Thread (Id : System.Address; Thread : System.Address);

   pragma Export (C, Get_Thread, "__gnat_get_thread");

   --  This procedure is used to retrieve the thread id of a given task.

   --  The value Id is the value that was passed to the thread code procedure

   --  at activation time.

   --  Thread is a pointer to a thread id that will be updated by this

   --  procedure.

   --

   --  C declaration:

   --

   --  extern void __gnat_get_thread (void *id, pthread_t *thread);

   function To_Task_Id

     (Id : System.Address)

      return Ada.Task_Identification.Task_Id;

   --  Ada interface only.

   --  Given a low level Id, as returned by Create_Thread, return a Task_Id,

   --  so that operations in Ada.Task_Identification can be used.

end GNAT.Threads;