------------------------------------------------------------------------------ -- -- -- 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 -- -- . -- -- -- -- 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;