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) 1992-2009, 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 package encapsulates and centralizes information about all uses of
33--  interrupts (or signals), including the target-dependent mapping of
34--  interrupts (or signals) to exceptions.
35
36--  Unlike the original design, System.Interrupt_Management can only be used
37--  for tasking systems.
38
39--  PLEASE DO NOT put any subprogram declarations with arguments of type
40--  Interrupt_ID into the visible part of this package. The type Interrupt_ID
41--  is used to derive the type in Ada.Interrupts, and adding more operations
42--  to that type would be illegal according to the Ada Reference Manual. This
43--  is the reason why the signals sets are implemented using visible arrays
44--  rather than functions.
45
46with System.OS_Interface;
47
48with Interfaces.C;
49
50package System.Interrupt_Management is
51   pragma Preelaborate;
52
53   type Interrupt_Mask is limited private;
54
55   type Interrupt_ID is new Interfaces.C.int
56     range 0 .. System.OS_Interface.Max_Interrupt;
57
58   type Interrupt_Set is array (Interrupt_ID) of Boolean;
59
60   --  The following objects serve as constants, but are initialized in the
61   --  body to aid portability. This permits us to use more portable names for
62   --  interrupts, where distinct names may map to the same interrupt ID
63   --  value.
64
65   --  For example, suppose SIGRARE is a signal that is not defined on all
66   --  systems, but is always reserved when it is defined. If we have the
67   --  convention that ID zero is not used for any "real" signals, and SIGRARE
68   --  = 0 when SIGRARE is not one of the locally supported signals, we can
69   --  write:
70   --     Reserved (SIGRARE) := True;
71   --  and the initialization code will be portable.
72
73   Abort_Task_Interrupt : Interrupt_ID;
74   --  The interrupt that is used to implement task abort if an interrupt is
75   --  used for that purpose. This is one of the reserved interrupts.
76
77   Keep_Unmasked : Interrupt_Set := (others => False);
78   --  Keep_Unmasked (I) is true iff the interrupt I is one that must that
79   --  must be kept unmasked at all times, except (perhaps) for short critical
80   --  sections. This includes interrupts that are mapped to exceptions (see
81   --  System.Interrupt_Exceptions.Is_Exception), but may also include
82   --  interrupts (e.g. timer) that need to be kept unmasked for other
83   --  reasons. Where interrupts are implemented as OS signals, and signal
84   --  masking is per-task, the interrupt should be unmasked in ALL TASKS.
85
86   Reserve : Interrupt_Set := (others => False);
87   --  Reserve (I) is true iff the interrupt I is one that cannot be permitted
88   --  to be attached to a user handler. The possible reasons are many. For
89   --  example, it may be mapped to an exception used to implement task abort,
90   --  or used to implement time delays.
91
92   procedure Initialize;
93   --  Initialize the various variables defined in this package. This procedure
94   --  must be called before accessing any object from this package, and can be
95   --  called multiple times.
96
97private
98   type Interrupt_Mask is new System.OS_Interface.sigset_t;
99   --  In some implementations Interrupt_Mask is represented as a linked list
100
101   procedure Adjust_Context_For_Raise
102     (Signo    : System.OS_Interface.Signal;
103      Ucontext : System.Address);
104   pragma Import
105     (C, Adjust_Context_For_Raise, "__gnat_adjust_context_for_raise");
106   --  Target specific hook performing adjustments to the signal's machine
107   --  context, to be called before an exception may be raised from a signal
108   --  handler. This service is provided by init.c, together with the
109   --  non-tasking signal handler.
110
111end System.Interrupt_Management;
112