C.3.2 The Package Interrupts
The following language-defined
Interrupt_Id is implementation-defined
access protected procedure
Is_Reserved (Interrupt : Interrupt_Id)
Is_Attached (Interrupt : Interrupt_Id)
Current_Handler (Interrupt : Interrupt_Id)
(New_Handler : in
Interrupt : in
(Old_Handler : out
New_Handler : in
Interrupt : in
(Interrupt : in
Reference (Interrupt : Interrupt_Id)
Get_CPU (Interrupt : Interrupt_Id)
... -- not specified by the language
. . .
The Interrupt_Id type is an implementation-defined
discrete type used to identify interrupts.
The Is_Reserved function returns True if and only
if the specified interrupt is reserved.
The Is_Attached function returns True if and only
if a user-specified interrupt handler is attached to the interrupt.
The Current_Handler function returns a value that
represents the attached handler of the interrupt. If no user-defined
handler is attached to the interrupt, Current_Handler returns null.
The Attach_Handler procedure attaches the specified
handler to the interrupt, overriding any existing treatment (including
a user handler) in effect for that interrupt. If New_Handler is null
the default treatment is restored.
designates a protected procedure for which the aspect Interrupt_Handler
is False, Program_Error is raised. In this case, the operation does not
modify the existing interrupt treatment.
The Exchange_Handler procedure operates in the same
manner as Attach_Handler with the addition that the value returned in
Old_Handler designates the previous treatment for the specified interrupt.
If the previous treatment is not a user-defined handler, null
The Detach_Handler procedure restores the default
treatment for the specified interrupt.
For all operations defined in this package that take
a parameter of type Interrupt_Id, with the exception of Is_Reserved and
Reference, a check is made that the specified interrupt is not reserved.
Program_Error is raised if this check fails.
If, by using the Attach_Handler, Detach_Handler,
or Exchange_Handler procedures, an attempt is made to detach a handler
that was attached statically (using the aspect Attach_Handler), the handler
is not detached and Program_Error is raised.
The Reference function returns a value of type System.Address
that can be used to attach a task entry via an address clause (see J.7.1
to the interrupt specified by Interrupt. This function raises Program_Error
if attaching task entries to interrupts (or to this particular interrupt)
is not supported.
The function Get_CPU returns the processor on
which the handler for Interrupt is executed. If the handler can execute
on more than one processor the value System.Multiprocessors.Not_A_Specific_CPU
At no time during attachment or exchange of handlers
shall the current handler of the corresponding interrupt be undefined.
If the Ceiling_Locking policy (see D.3
is in effect, the implementation shall document the default ceiling priority
assigned to a protected object that contains a protected procedure that
specifies either the Attach_Handler or Interrupt_Handler aspects, but
does not specify the Interrupt_Priority aspect. This default need not
be the same for all interrupts.
If implementation-defined forms of interrupt handler
procedures are supported, such as protected procedures with parameters,
then for each such form of a handler, a type analogous to Parameterless_Handler
should be specified in a child package of Interrupts, with the same operations
as in the predefined package Interrupts.
8 The package Interrupts.Names contains
implementation-defined names (and constant values) for the interrupts
that are supported by the implementation.
Example of interrupt
Device_Priority : constant
array (1..5) of System.Interrupt_Priority := ( ... );
protected type Device_Interface
(Int_Id : Ada.Interrupts.Interrupt_Id)
with Interrupt_Priority => Device_Priority(Int_Id) is
with Attach_Handler => Int_Id;
Device_1_Driver : Device_Interface(1);
Device_5_Driver : Device_Interface(5);
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