102 lines
4.8 KiB
Ada
102 lines
4.8 KiB
Ada
------------------------------------------------------------------------------
|
|
-- --
|
|
-- GNAT LIBRARY COMPONENTS --
|
|
-- --
|
|
-- G N A T . B O U N D E D _ B U F F E R S --
|
|
-- --
|
|
-- S p e c --
|
|
-- --
|
|
-- Copyright (C) 2003-2010, AdaCore --
|
|
-- --
|
|
-- GNAT 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/>. --
|
|
-- --
|
|
-- GNAT was originally developed by the GNAT team at New York University. --
|
|
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
|
|
-- --
|
|
------------------------------------------------------------------------------
|
|
|
|
-- This package provides a thread-safe generic bounded buffer abstraction.
|
|
-- Instances are useful directly or as parts of the implementations of other
|
|
-- abstractions, such as mailboxes.
|
|
|
|
-- Bounded_Buffer is declared explicitly as a protected type, rather than as
|
|
-- a simple limited private type completed as a protected type, so that
|
|
-- clients may make calls accordingly (i.e., conditional/timed entry calls).
|
|
|
|
with System;
|
|
|
|
generic
|
|
type Element is private;
|
|
-- The type of the values contained within buffer objects
|
|
|
|
package GNAT.Bounded_Buffers is
|
|
pragma Pure;
|
|
|
|
type Content is array (Positive range <>) of Element;
|
|
-- Content is an internal artefact that cannot be hidden because protected
|
|
-- types cannot contain type declarations.
|
|
|
|
Default_Ceiling : constant System.Priority := System.Default_Priority;
|
|
-- A convenience value for the Ceiling discriminant
|
|
|
|
protected type Bounded_Buffer
|
|
(Capacity : Positive;
|
|
-- Objects of type Bounded_Buffer specify the maximum number of Element
|
|
-- values they can hold via the discriminant Capacity.
|
|
|
|
Ceiling : System.Priority)
|
|
-- Users must specify the ceiling priority for the object. If the
|
|
-- Real-Time Systems Annex is not in use this value is not important.
|
|
is
|
|
pragma Priority (Ceiling);
|
|
|
|
entry Insert (Item : Element);
|
|
-- Insert Item into the buffer, blocks caller until space is available
|
|
|
|
entry Remove (Item : out Element);
|
|
-- Remove next available Element from buffer. Blocks caller until an
|
|
-- Element is available.
|
|
|
|
function Empty return Boolean;
|
|
-- Returns whether the instance contains any Elements.
|
|
-- Note: State may change immediately after call returns.
|
|
|
|
function Full return Boolean;
|
|
-- Returns whether any space remains within the instance.
|
|
-- Note: State may change immediately after call returns.
|
|
|
|
function Extent return Natural;
|
|
-- Returns the number of Element values currently held
|
|
-- within the instance.
|
|
-- Note: State may change immediately after call returns.
|
|
|
|
private
|
|
Values : Content (1 .. Capacity);
|
|
-- The container for the values held by the buffer instance
|
|
|
|
Next_In : Positive := 1;
|
|
-- The index of the next Element inserted. Wraps around
|
|
|
|
Next_Out : Positive := 1;
|
|
-- The index of the next Element removed. Wraps around
|
|
|
|
Count : Natural := 0;
|
|
-- The number of Elements currently held
|
|
end Bounded_Buffer;
|
|
|
|
end GNAT.Bounded_Buffers;
|