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------------------------------------------------------------------------------
-- --
-- GNU ADA 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) 1991-2001 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 2, or (at your option) any later ver- --
-- sion. GNARL 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. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNARL; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. It is --
-- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
-- State University (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
--
-- 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.
-- This is designed to work for both tasking and non-tasking systems,
-- without pulling in any of the tasking support.
-- PLEASE DO NOT remove the Elaborate_Body pragma from this package.
-- Elaboration of this package should happen early, as most other
-- initializations depend on it.
-- Forcing immediate elaboration of the body also helps to enforce
-- the design assumption that this is a second-level
-- package, just one level above System.OS_Interface, with no
-- cross-dependences.
-- 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;
-- used for Signal
-- sigset_t
package System.Interrupt_Management is
pragma Elaborate_Body;
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;
-- and the initialization code will be portable.
Abort_Task_Interrupt : Interrupt_ID;
-- The interrupt that is used to implement task abortion,
-- 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 abortion,
-- or used to implement time delays.
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_Interrupts;
-- On systems where there is no signal inheritance between tasks (e.g
-- VxWorks, GNU/LinuxThreads), this procedure is used to initialize
-- interrupts handling in each task. Otherwise this function should
-- only be called by initialize in this package body.
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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