1------------------------------------------------------------------------------
2--                                                                          --
3--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
4--                                                                          --
5--            S Y S T E M . I N T E R R U P T _ M A N A G E M E N T         --
6--                                                                          --
7--                                  S p e c                                 --
8--                                                                          --
9--          Copyright (C) 1991-2009, 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 the Alpha/VMS version of this package
33
34--  This package encapsulates and centralizes information about all uses of
35--  interrupts (or signals), including the target-dependent mapping of
36--  interrupts (or signals) to exceptions.
37
38--  PLEASE DO NOT add any with-clauses to this package
39
40--  PLEASE DO NOT put any subprogram declarations with arguments of type
41--  Interrupt_ID into the visible part of this package.
42
43--  The type Interrupt_ID is used to derive the type in Ada.Interrupts, and
44--  adding more operations to that type would be illegal according to the Ada
45--  Reference Manual. (This is the reason why the signals sets below are
46--  implemented as visible arrays rather than functions.)
47
48with System.OS_Interface;
49
50package System.Interrupt_Management is
51   pragma Preelaborate;
52
53   type Interrupt_Mask is limited private;
54
55   type Interrupt_ID is new System.OS_Interface.Signal;
56
57   type Interrupt_Set is array (Interrupt_ID) of Boolean;
58
59   --  The following objects serve as constants, but are initialized in the
60   --  body to aid portability. This permits us to use more portable names for
61   --  interrupts, where distinct names may map to the same interrupt ID
62   --  value. For example, suppose SIGRARE is a signal that is not defined on
63   --  all systems, but is always reserved when it is defined. If we have the
64   --  convention that ID zero is not used for any "real" signals, and SIGRARE
65   --  = 0 when SIGRARE is not one of the locally supported signals, we can
66   --  write:
67   --     Reserved (SIGRARE) := true;
68   --  Then the initialization code will be portable.
69
70   Abort_Task_Interrupt : Interrupt_ID;
71   --  The interrupt that is used to implement task abort, if an interrupt is
72   --  used for that purpose. This is one of the reserved interrupts.
73
74   Keep_Unmasked : Interrupt_Set := (others => False);
75   --  Keep_Unmasked (I) is true iff the interrupt I is one that must be kept
76   --  unmasked at all times, except (perhaps) for short critical sections.
77   --  This includes interrupts that are mapped to exceptions (see
78   --  System.Interrupt_Exceptions.Is_Exception), but may also include
79   --  interrupts (e.g. timer) that need to be kept unmasked for other
80   --  reasons. Where interrupts are implemented as OS signals, and signal
81   --  masking is per-task, the interrupt should be unmasked in ALL TASKS.
82
83   Reserve : Interrupt_Set := (others => False);
84   --  Reserve (I) is true iff the interrupt I is one that cannot be permitted
85   --  to be attached to a user handler. The possible reasons are many. For
86   --  example it may be mapped to an exception used to implement task abort.
87
88   Keep_Masked : Interrupt_Set := (others => False);
89   --  Keep_Masked (I) is true iff the interrupt I must always be masked.
90   --  Where interrupts are implemented as OS signals, and signal masking is
91   --  per-task, the interrupt should be masked in ALL TASKS. There might not
92   --  be any interrupts in this class, depending on the environment. For
93   --  example, if interrupts are OS signals and signal masking is per-task,
94   --  use of the sigwait operation requires the signal be masked in all tasks.
95
96   procedure Initialize;
97   --  Initialize the various variables defined in this package.
98   --  This procedure must be called before accessing any object from this
99   --  package and can be called multiple times.
100
101private
102   use type System.OS_Interface.unsigned_long;
103
104   type Interrupt_Mask is new System.OS_Interface.sigset_t;
105
106   --  Interrupts on VMS are implemented with a mailbox. A QIO read is
107   --  registered on the Rcv channel and the interrupt occurs by registering
108   --  a QIO write on the Snd channel. The maximum number of pending
109   --  interrupts is arbitrarily set at 1000. One nice feature of using
110   --  a mailbox is that it is trivially extendable to cross process
111   --  interrupts.
112
113   Rcv_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
114   Snd_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
115   Interrupt_Mailbox  : Interrupt_ID := 0;
116   Interrupt_Bufquo   : System.OS_Interface.unsigned_long :=
117                          1000 * (Interrupt_ID'Size / 8);
118
119end System.Interrupt_Management;
120