File : circular_stream.ads
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-- ADAGIO - ADALID - AENEA. --
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-- Copyright (C) 2003 --
-- A. Mosteo. --
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-- $Id: circular_stream.ads,v 1.4 2004/01/21 21:05:43 Jano Exp $
-- Circular stream. This is a buffering stream where the written data
-- can be read afterwards in typical producer/consumer fashion.
with Ada.Finalization;
with Ada.Streams; use Ada.Streams;
use Ada;
package Circular_stream is
type Stream_access is access all Ada.Streams.Root_stream_type'Class;
------------------------------------------------------------------------
-- Stream_type --
------------------------------------------------------------------------
-- The size of the intermediate buffer is the maximum non-read data we
-- can have:
type Stream_type (Size : Stream_element_count) is new
Ada.Streams.Root_Stream_Type with private;
type Object_access is access all Stream_type;
------------------------------------------------------------------------
-- Overriden primitives --
------------------------------------------------------------------------
procedure Read(
Stream : in out Stream_type;
Item : out Stream_Element_Array;
Last : out Stream_Element_Offset);
procedure Write(
Stream : in out Stream_type;
Item : in Stream_Element_Array);
------------------------------------------------------------------------
-- Available_read --
------------------------------------------------------------------------
-- Says how many data has been written but not read:
function Available_read (Stream : in Stream_type)
return Stream_element_count;
function Available_read (Stream : in Stream_type)
return Natural;
pragma Inline (Available_read);
------------------------------------------------------------------------
-- Available_write --
------------------------------------------------------------------------
-- Says how many data can be written to the stream:
function Available_write (Stream : in Stream_type)
return Stream_element_count;
function Available_write (Stream : in Stream_type)
return Natural;
pragma Inline (Available_write);
------------------------------------------------------------------------
-- Reset --
------------------------------------------------------------------------
-- Resets everything to the starting point
procedure Reset (Stream : in out Stream_type);
private
subtype Buffer_type is
Stream_element_array;
type Buffer_type_access is access all Buffer_type;
-- Allocation is made in the first use to delay memory consumption:
type Controlled_buffer_type (Size : Stream_element_count) is new
Finalization.Controlled with
record
Data: Buffer_type_access;
end record;
procedure Finalize (this: in out Controlled_buffer_type);
type Stream_type (Size : Stream_element_count) is new
Ada.Streams.Root_Stream_Type
with record
Buffer : Controlled_buffer_type (Size);
Pos_read : Stream_element_offset := 1; -- Next element to read.
Pos_Write : Stream_element_offset := 1; -- Next element to write.
Available_read : Stream_element_count := 0; -- Pending for read data.
end record;
end Circular_stream;