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------------------------------------------------------------------------------

--                                                                          --

--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --

--                                                                          --

--            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         --

--                                                                          --

--                                  S p e c                                 --

--                                                                          --

--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- GNARL is free software; you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNARL was developed by the GNARL team at Florida State University.       --

-- Extensive contributions were provided by Ada Core Technologies, Inc.     --

--                                                                          --

------------------------------------------------------------------------------

--  This package encapsulates and centralizes information about all uses of

--  interrupts (or signals), including the target-dependent mapping of

--  interrupts (or signals) to exceptions.

--  Unlike the original design, System.Interrupt_Management can only be used

--  for tasking systems.

--  PLEASE DO NOT put any subprogram declarations with arguments of type

--  Interrupt_ID into the visible part of this package. The type Interrupt_ID

--  is used to derive the type in Ada.Interrupts, and adding more operations

--  to that type would be illegal according to the Ada Reference Manual. This

--  is the reason why the signals sets are implemented using visible arrays

--  rather than functions.

with System.OS_Interface;

with Interfaces.C;

package System.Interrupt_Management is

   pragma Preelaborate;

   type Interrupt_Mask is limited private;

   type Interrupt_ID is new Interfaces.C.int

     range 0 .. System.OS_Interface.Max_Interrupt;

   type Interrupt_Set is array (Interrupt_ID) of Boolean;

   --  The following objects serve as constants, but are initialized in the

   --  body to aid portability. This permits us to use more portable names for

   --  interrupts, where distinct names may map to the same interrupt ID

   --  value.

   --  For example, suppose SIGRARE is a signal that is not defined on all

   --  systems, but is always reserved when it is defined. If we have the

   --  convention that ID zero is not used for any "real" signals, and SIGRARE

   --  = 0 when SIGRARE is not one of the locally supported signals, we can

   --  write:

   --     Reserved (SIGRARE) := True;

   --  and the initialization code will be portable.

   Abort_Task_Interrupt : Interrupt_ID;

   --  The interrupt that is used to implement task abort if an interrupt is

   --  used for that purpose. This is one of the reserved interrupts.

   Keep_Unmasked : Interrupt_Set := (others => False);

   --  Keep_Unmasked (I) is true iff the interrupt I is one that must that

   --  must be kept unmasked at all times, except (perhaps) for short critical

   --  sections. This includes interrupts that are mapped to exceptions (see

   --  System.Interrupt_Exceptions.Is_Exception), but may also include

   --  interrupts (e.g. timer) that need to be kept unmasked for other

   --  reasons. Where interrupts are implemented as OS signals, and signal

   --  masking is per-task, the interrupt should be unmasked in ALL TASKS.

   Reserve : Interrupt_Set := (others => False);

   --  Reserve (I) is true iff the interrupt I is one that cannot be permitted

   --  to be attached to a user handler. The possible reasons are many. For

   --  example, it may be mapped to an exception used to implement task abort,

   --  or used to implement time delays.

   procedure Initialize;

   --  Initialize the various variables defined in this package. This procedure

   --  must be called before accessing any object from this package, and can be

   --  called multiple times.

private

   type Interrupt_Mask is new System.OS_Interface.sigset_t;

   --  In some implementations Interrupt_Mask is represented as a linked list

   procedure Adjust_Context_For_Raise

     (Signo    : System.OS_Interface.Signal;

      Ucontext : System.Address);

   pragma Import

     (C, Adjust_Context_For_Raise, "__gnat_adjust_context_for_raise");

   --  Target specific hook performing adjustments to the signal's machine

   --  context, to be called before an exception may be raised from a signal

   --  handler. This service is provided by init.c, together with the

   --  non-tasking signal handler.

end System.Interrupt_Management;