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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) 1991-2009, 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 is the Alpha/VMS version of this package
-- This package encapsulates and centralizes information about all uses of
-- interrupts (or signals), including the target-dependent mapping of
-- interrupts (or signals) to exceptions.
-- PLEASE DO NOT add any with-clauses to this package
-- 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 below are
-- implemented as visible arrays rather than functions.)
with System.OS_Interface;
package System.Interrupt_Management is
pragma Preelaborate;
type Interrupt_Mask is limited private;
type Interrupt_ID is new System.OS_Interface.Signal;
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;
-- Then 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 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.
Keep_Masked : Interrupt_Set := (others => False);
-- Keep_Masked (I) is true iff the interrupt I must always be masked.
-- Where interrupts are implemented as OS signals, and signal masking is
-- per-task, the interrupt should be masked in ALL TASKS. There might not
-- be any interrupts in this class, depending on the environment. For
-- example, if interrupts are OS signals and signal masking is per-task,
-- use of the sigwait operation requires the signal be masked in all tasks.
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
use type System.OS_Interface.unsigned_long;
type Interrupt_Mask is new System.OS_Interface.sigset_t;
-- Interrupts on VMS are implemented with a mailbox. A QIO read is
-- registered on the Rcv channel and the interrupt occurs by registering
-- a QIO write on the Snd channel. The maximum number of pending
-- interrupts is arbitrarily set at 1000. One nice feature of using
-- a mailbox is that it is trivially extendable to cross process
-- interrupts.
Rcv_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
Snd_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
Interrupt_Mailbox : Interrupt_ID := 0;
Interrupt_Bufquo : System.OS_Interface.unsigned_long :=
1000 * (Interrupt_ID'Size / 8);
end System.Interrupt_Management;
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