1------------------------------------------------------------------------------
2--                                                                          --
3--                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
4--                                                                          --
5--                 S Y S T E M . T A S K _ P R I M I T I V E S              --
6--                                                                          --
7--                                  S p e c                                 --
8--                                                                          --
9--           Copyright (C) 1991-2001 Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNARL 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. GNARL 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 GNARL; see file COPYING.  If not, write --
19-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
20-- MA 02111-1307, 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-- GNARL was developed by the GNARL team at Florida State University.       --
30-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
31--                                                                          --
32------------------------------------------------------------------------------
33
34--  This is the GNU/Linux (GNU/LinuxThreads) version of this package.
35
36--  This package provides low-level support for most tasking features.
37
38pragma Polling (Off);
39--  Turn off polling, we do not want ATC polling to take place during
40--  tasking operations. It causes infinite loops and other problems.
41
42with System.OS_Interface;
43--  used for pthread_mutex_t
44--           pthread_cond_t
45--           pthread_t
46
47package System.Task_Primitives is
48
49   type Lock is limited private;
50   --  Should be used for implementation of protected objects.
51
52   type RTS_Lock is limited private;
53   --  Should be used inside the runtime system.
54   --  The difference between Lock and the RTS_Lock is that the later
55   --  one serves only as a semaphore so that do not check for
56   --  ceiling violations.
57
58   type Task_Body_Access is access procedure;
59   --  Pointer to the task body's entry point (or possibly a wrapper
60   --  declared local to the GNARL).
61
62   type Private_Data is limited private;
63   --  Any information that the GNULLI needs maintained on a per-task
64   --  basis.  A component of this type is guaranteed to be included
65   --  in the Ada_Task_Control_Block.
66
67private
68
69   type Prio_Array_Type is array (System.Any_Priority) of Integer;
70
71   type Lock is record
72      L          : aliased System.OS_Interface.pthread_mutex_t;
73      Ceiling    : System.Any_Priority := System.Any_Priority'First;
74      Saved_Priority : System.Any_Priority := System.Any_Priority'First;
75   end record;
76
77   type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
78   type Private_Data is record
79      Thread      : aliased System.OS_Interface.pthread_t;
80      pragma Atomic (Thread);
81      --  Thread field may be updated by two different threads of control.
82      --  (See, Enter_Task and Create_Task in s-taprop.adb).
83      --  They put the same value (thr_self value). We do not want to
84      --  use lock on those operations and the only thing we have to
85      --  make sure is that they are updated in atomic fashion.
86
87      CV          : aliased System.OS_Interface.pthread_cond_t;
88      L           : aliased RTS_Lock;
89      --  protection for all components is lock L
90
91      Active_Priority : System.Any_Priority := System.Any_Priority'First;
92      --  Simulated active priority,
93      --  used only if Priority_Ceiling_Support is True.
94   end record;
95
96end System.Task_Primitives;
97