Package Name: system.interrupt_management

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------------------------------------------------------------------------------
--                                                                          --
--                 GNU ADA RUNTIME 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         --
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--                                  S p e c                                 --
--                         (Version for new GNARL)                          --
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--    Copyright (C) 1991,92,93,94,95,1996 Free Software Foundation, Inc.    --
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------------------------------------------------------------------------------
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.
private
   type Interrupt_Mask is new System.OS_Interface.sigset_t;
   --  in some implementation Interrupt_Mask can be represented
   --  as a linked list.
   procedure Initialize;
   --  to advertise the work done by the body
end System.Interrupt_Management;