| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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; |
