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Diffstat (limited to 'gcc/ada/g-boubuf.ads')
| -rw-r--r-- | gcc/ada/g-boubuf.ads | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/gcc/ada/g-boubuf.ads b/gcc/ada/g-boubuf.ads new file mode 100644 index 00000000000..8eb478bd3e4 --- /dev/null +++ b/gcc/ada/g-boubuf.ads @@ -0,0 +1,101 @@ +------------------------------------------------------------------------------ +-- -- +-- 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 Ada Core Technologies, Inc. -- +-- -- +-- 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 2, 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. See the GNU General Public License -- +-- for more details. You should have received a copy of the GNU General -- +-- Public License distributed with GNAT; see file COPYING. If not, write -- +-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- +-- MA 02111-1307, USA. -- +-- -- +-- As a special exception, if other files instantiate generics from this -- +-- unit, or you link this unit with other files to produce an executable, -- +-- this unit does not by itself cause the resulting executable to be -- +-- covered by the GNU General Public License. This exception does not -- +-- however invalidate any other reasons why the executable file might be -- +-- covered by the GNU Public License. -- +-- -- +-- 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 : in 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; |