gcc/ada/g-thread.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                         G N A T . T H R E A D S                          --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                     Copyright (C) 1998-2007, AdaCore                     --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This package provides facilities for creation or registration of foreign
  35 --  threads for use as Ada tasks. In order to execute general Ada code, the
  36 --  run-time system must know about all tasks. This package allows foreign
  37 --  code, e.g. a C program, to create a thread that the Ada run-time knows
  38 --  about, or to register the current thread.
  39
  40 --  For some implementations of GNAT Pro, the registration of foreign threads
  41 --  is automatic. However, in such implementations, if the Ada program has no
  42 --  tasks at all and no tasking constructs other than delay, then by default
  43 --  the non-tasking version of the Ada run-time will be loaded. If foreign
  44 --  threads are present, it is important to ensure that the tasking version
  45 --  of the Ada run time is loaded. This may be achieved by adding "with
  46 --  GNAT.Threads" to any unit in the partition.
  47
  48 with System;
  49 with Ada.Task_Identification;
  50
  51 package GNAT.Threads is
  52
  53    type Void_Ptr is access all Integer;
  54
  55    function Create_Thread
  56      (Code : System.Address;  -- pointer
  57       Parm : Void_Ptr;        -- pointer
  58       Size : Natural;         -- int
  59       Prio : Integer)         -- int
  60       return System.Address;
  61    pragma Export (C, Create_Thread, "__gnat_create_thread");
  62    --  Creates a thread with the given (Size) stack size in bytes, and
  63    --  the given (Prio) priority. The task will execute a call to the
  64    --  procedure whose address is given by Code. This procedure has
  65    --  the prototype
  66    --
  67    --    void thread_code (void *id, void *parm);
  68    --
  69    --  where id is the id of the created task, and parm is the parameter
  70    --  passed to Create_Thread. The called procedure is the body of the
  71    --  code for the task, the task will be automatically terminated when
  72    --  the procedure returns.
  73    --
  74    --  This function returns the Ada Id of the created task that can then be
  75    --  used as a parameter to the procedures below.
  76    --
  77    --  C declaration:
  78    --
  79    --  extern void *__gnat_create_thread
  80    --    (void (*code)(void *, void *), void *parm, int size, int prio);
  81
  82    function Register_Thread return System.Address;
  83    pragma Export (C, Register_Thread, "__gnat_register_thread");
  84    --  Create an Ada task Id for the current thread if needed.
  85    --  If the thread could not be registered, System.Null_Address is returned.
  86    --
  87    --  This function returns the Ada Id of the current task that can then be
  88    --  used as a parameter to the procedures below.
  89    --
  90    --  C declaration:
  91    --
  92    --  extern void *__gnat_register_thread ();
  93    --
  94    --  Here is a typical usage of the Register/Unregister_Thread procedures:
  95    --
  96    --  void thread_body ()
  97    --  {
  98    --    void *task_id = __gnat_register_thread ();
  99    --    ... thread body ...
 100    --    __gnat_unregister_thread ();
 101    --  }
 102
 103    procedure Unregister_Thread;
 104    pragma Export (C, Unregister_Thread, "__gnat_unregister_thread");
 105    --  Unregister the current task from the GNAT run time and destroy the
 106    --  memory allocated for its task id.
 107    --
 108    --  C declaration:
 109    --
 110    --  extern void __gnat_unregister_thread ();
 111
 112    procedure Unregister_Thread_Id (Thread : System.Address);
 113    pragma Export (C, Unregister_Thread_Id, "__gnat_unregister_thread_id");
 114    --  Unregister the task associated with Thread from the GNAT run time and
 115    --  destroy the memory allocated for its task id.
 116    --  If no task id is associated with Thread, do nothing.
 117    --
 118    --  C declaration:
 119    --
 120    --  extern void __gnat_unregister_thread_id (pthread_t *thread);
 121
 122    procedure Destroy_Thread (Id : System.Address);
 123    pragma Export (C, Destroy_Thread, "__gnat_destroy_thread");
 124    --  This procedure may be used to prematurely abort the created thread.
 125    --  The value Id is the value that was passed to the thread code procedure
 126    --  at activation time.
 127    --
 128    --  C declaration:
 129    --
 130    --  extern void __gnat_destroy_thread (void *id);
 131
 132    procedure Get_Thread (Id : System.Address; Thread : System.Address);
 133    pragma Export (C, Get_Thread, "__gnat_get_thread");
 134    --  This procedure is used to retrieve the thread id of a given task.
 135    --  The value Id is the value that was passed to the thread code procedure
 136    --  at activation time.
 137    --  Thread is a pointer to a thread id that will be updated by this
 138    --  procedure.
 139    --
 140    --  C declaration:
 141    --
 142    --  extern void __gnat_get_thread (void *id, pthread_t *thread);
 143
 144    function To_Task_Id
 145      (Id : System.Address)
 146       return Ada.Task_Identification.Task_Id;
 147    --  Ada interface only.
 148    --  Given a low level Id, as returned by Create_Thread, return a Task_Id,
 149    --  so that operations in Ada.Task_Identification can be used.
 150
 151 end GNAT.Threads;