1------------------------------------------------------------------------------
2--                                                                          --
3--                 GNAT 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) 1991-2011, 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 3,  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.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNARL was developed by the GNARL team at Florida State University.       --
28-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This is a OpenVMS/Alpha version of this package
33
34--  This package provides low-level support for most tasking features
35
36pragma Polling (Off);
37--  Turn off polling, we do not want ATC polling to take place during tasking
38--  operations. It causes infinite loops and other problems.
39
40with Interfaces.C;
41
42with System.OS_Interface;
43with System.Aux_DEC;
44
45package System.Task_Primitives is
46   pragma Preelaborate;
47
48   type Lock is limited private;
49   --  Should be used for implementation of protected objects
50
51   type RTS_Lock is limited private;
52   --  Should be used inside the runtime system. The difference between Lock
53   --  and the RTS_Lock is that the later one serves only as a semaphore so
54   --  that do not check for ceiling violations.
55
56   type Suspension_Object is limited private;
57   --  Should be used for the implementation of Ada.Synchronous_Task_Control
58
59   type Task_Body_Access is access procedure;
60   --  Pointer to the task body's entry point (or possibly a wrapper
61   --  declared local to the GNARL).
62
63   type Private_Data is limited private;
64   --  Any information that the GNULLI needs maintained on a per-task basis.
65   --  A component of this type is guaranteed to be included in the
66   --  Ada_Task_Control_Block.
67
68   subtype Task_Address is System.Aux_DEC.Short_Address;
69   --  Task_Address is the short version of address defined in System.Aux_DEC.
70   --  To avoid dragging Aux_DEC into tasking packages a tasking specific
71   --  subtype is defined here.
72
73   Task_Address_Size : constant := System.Aux_DEC.Short_Address_Size;
74   --  The size of Task_Address
75
76   Alternate_Stack_Size : constant := 0;
77   --  No alternate signal stack is used on this platform
78
79private
80
81   type Lock is record
82      L         : aliased System.OS_Interface.pthread_mutex_t;
83      Prio      : Interfaces.C.int;
84      Prio_Save : Interfaces.C.int;
85   end record;
86
87   type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
88
89   type Suspension_Object is record
90      State   : Boolean;
91      pragma Atomic (State);
92      --  Boolean that indicates whether the object is open. This field is
93      --  marked Atomic to ensure that we can read its value without locking
94      --  the access to the Suspension_Object.
95
96      Waiting : Boolean;
97      --  Flag showing if there is a task already suspended on this object
98
99      L : aliased System.OS_Interface.pthread_mutex_t;
100      --  Protection for ensuring mutual exclusion on the Suspension_Object
101
102      CV : aliased System.OS_Interface.pthread_cond_t;
103      --  Condition variable used to queue threads until ondition is signaled
104   end record;
105
106   type Private_Data is record
107      Thread : aliased System.OS_Interface.pthread_t;
108      pragma Atomic (Thread);
109      --  Thread field may be updated by two different threads of control.
110      --  (See, Enter_Task and Create_Task in s-taprop.adb). They put the
111      --  same value (thr_self value). We do not want to use lock on those
112      --  operations and the only thing we have to make sure is that they
113      --  are updated in atomic fashion.
114
115      CV : aliased System.OS_Interface.pthread_cond_t;
116
117      L : aliased RTS_Lock;
118      --  Protection for all components is lock L
119
120      AST_Pending : Boolean;
121      --  Used to detect delay and sleep timeouts
122
123   end record;
124
125end System.Task_Primitives;
126