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) 1991-2012, 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 HP-UX 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 System.OS_Interface;
41
42package System.Task_Primitives is
43   pragma Preelaborate;
44
45   type Lock is limited private;
46   --  Should be used for implementation of protected objects
47
48   type RTS_Lock is limited private;
49   --  Should be used inside the runtime system. The difference between Lock
50   --  and the RTS_Lock is that the later one serves only as a semaphore so
51   --  that do not check for ceiling violations.
52
53   type Suspension_Object is limited private;
54   --  Should be used for the implementation of Ada.Synchronous_Task_Control
55
56   type Task_Body_Access is access procedure;
57   --  Pointer to the task body's entry point (or possibly a wrapper
58   --  declared local to the GNARL).
59
60   type Private_Data is limited private;
61   --  Any information that the GNULLI needs maintained on a per-task basis.
62   --  A component of this type is guaranteed to be included in the
63   --  Ada_Task_Control_Block.
64
65   subtype Task_Address is System.Address;
66   --  In some versions of Task_Primitives, notably for VMS, Task_Address is
67   --  the short version of address defined in System.Aux_DEC. To avoid
68   --  dragging Aux_DEC into tasking packages a tasking specific subtype is
69   --  defined here.
70
71   Task_Address_Size : constant := Standard'Address_Size;
72   --  The size of Task_Address
73
74   Alternate_Stack_Size : constant := 0;
75   --  No alternate signal stack is used on this platform
76
77private
78   type Lock is record
79      L              : aliased System.OS_Interface.pthread_mutex_t;
80      Priority       : Integer;
81      Owner_Priority : Integer;
82   end record;
83
84   type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
85
86   type Suspension_Object is record
87      State   : Boolean;
88      pragma Atomic (State);
89      --  Boolean that indicates whether the object is open. This field is
90      --  marked Atomic to ensure that we can read its value without locking
91      --  the access to the Suspension_Object.
92
93      Waiting : Boolean;
94      --  Flag showing if there is a task already suspended on this object
95
96      L : aliased System.OS_Interface.pthread_mutex_t;
97      --  Protection for ensuring mutual exclusion on the Suspension_Object
98
99      CV : aliased System.OS_Interface.pthread_cond_t;
100      --  Condition variable used to queue threads until condition is signaled
101   end record;
102
103   type Private_Data is record
104      Thread : aliased System.OS_Interface.pthread_t;
105      --  pragma Atomic (Thread);
106      --  Unfortunately, the above fails because Thread is 64 bits.
107
108      --  Thread field may be updated by two different threads of control.
109      --  (See, Enter_Task and Create_Task in s-taprop.adb). They put the
110      --  same value (thr_self value). We do not want to use lock on those
111      --  operations and the only thing we have to make sure is that they
112      --  are updated in atomic fashion.
113
114      CV : aliased System.OS_Interface.pthread_cond_t;
115
116      L : aliased RTS_Lock;
117      --  Protection for all components is lock L
118   end record;
119
120end System.Task_Primitives;
121