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-- --
-- package Block_Streams Copyright (c) Dmitry A. Kazakov --
-- Interface Luebeck --
-- Autumn, 2011 --
-- --
-- Last revision : 10:35 22 Oct 2011 --
-- --
-- This library is free software; you can redistribute it and/or --
-- modify it under the terms of the GNU General Public License as --
-- published by the Free Software Foundation; either version 2 of --
-- the License, or (at your option) any later version. This library --
-- is distributed in the hope that it will be useful, but WITHOUT --
-- 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 along with --
-- this library; if not, write to the Free Software Foundation, --
-- Inc., 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. --
--____________________________________________________________________--
--
-- Block stream is a stream formatted as a sequence of blocks. Each
-- block has fixed size, a sequence number and the check sum. Blocks
-- are read and written into the transport stream. Upon the stream of
-- blocks the interface stream is defined that verifies the block
-- numbers, their check sums and exposes the block contents as a new
-- stream.
--
-- ._________________________________________.
-- | |
-- | Data stream |
-- |_________________________________________|
-- .__________. .__________. .___________.
-- | | | | | |
-- | Block 0 | | Block 1 | ... | Block n |
-- |__________| |__________| |___________|
-- ._________________________________________.
-- | |
-- | Transport stream of stream elements |
-- |_________________________________________|
--
with Ada.Streams; use Ada.Streams;
with Interfaces; use Interfaces;
with Ada.Finalization;
package Block_Streams is
--
-- Input_Block_Stream -- Stream reads blocks from a stream. Blocks have
-- sequence numbers and supplied with the check
-- sum.
--
-- Transport - The transport stream carrying the blocks
--
type Input_Block_Stream
( Transport : access Root_Stream_Type'Class;
Size : Stream_Element_Count
) is new Root_Stream_Type with private;
--
-- Get_Block_No -- Current block number
--
-- Stream - The input stream
--
-- Returns :
--
-- The block number being read 1..
--
function Get_Block_No
( Stream : Input_Block_Stream
) return Unsigned_32;
--
-- Get_Element_No -- Current stream element number
--
-- Stream - The input stream
--
-- Returns :
--
-- The number of the stream element to read (within the block) 1..
--
function Get_Element_No
( Stream : Input_Block_Stream
) return Stream_Element_Count;
--
-- Skip -- Resynchronize the stream
--
-- Stream - To skip
--
-- This procedure is called to resynchronize the input stream with the
-- block of the sequence number 0.
--
-- Exceptions :
--
-- Any - I/O error
--
procedure Skip (Stream : in out Input_Block_Stream);
--
-- Output_Block_Stream -- Stream writes blocks onto a stream. Blocks
-- have sequence numbers and supplied with the
-- check sum.
--
-- Transport - The transport stream carrying the blocks
--
type Output_Block_Stream
( Transport : access Root_Stream_Type'Class;
Size : Stream_Element_Count
) is new Root_Stream_Type with private;
--
-- Flush -- Write the last block onto the stream
--
-- Stream - To flush
--
-- This procedure is called to write the last block if there is any
-- pending output. After that Write can be used again starting with the
-- sequence number 0.
--
-- Exceptions :
--
-- Any - I/O error
--
procedure Flush (Stream : in out Output_Block_Stream);
--
-- Get_Block_No -- Current block number
--
-- Stream - The output stream
--
-- Returns :
--
-- The block number being written 1..
--
function Get_Block_No
( Stream : Output_Block_Stream
) return Unsigned_32;
--
-- Get_Element_No -- Current stream element number
--
-- Stream - The output stream
--
-- Returns :
--
-- The number of the stream element to write (within the block) 1..
--
function Get_Element_No
( Stream : Output_Block_Stream
) return Stream_Element_Count;
--
-- Overridden operations
--
procedure Read
( Stream : in out Input_Block_Stream;
Item : out Stream_Element_Array;
Last : out Stream_Element_Offset
);
procedure Read
( Stream : in out Output_Block_Stream;
Item : out Stream_Element_Array;
Last : out Stream_Element_Offset
);
procedure Write
( Stream : in out Input_Block_Stream;
Item : Stream_Element_Array
);
procedure Write
( Stream : in out Output_Block_Stream;
Item : Stream_Element_Array
);
private
type Input_Block_Stream
( Transport : access Root_Stream_Type'Class;
Size : Stream_Element_Count
) is new Root_Stream_Type with
record
No : Unsigned_32 := 0;
Index : Stream_Element_Offset := Size - 6 + 1;
Buffer : Stream_Element_Array (1..Size);
end record;
type Controlled
( Output : access Output_Block_Stream'Class
) is new Ada.Finalization.Limited_Controlled with null record;
procedure Finalize (Object : in out Controlled);
type Output_Block_Stream
( Transport : access Root_Stream_Type'Class;
Size : Stream_Element_Count
) is new Root_Stream_Type with
record
No : Unsigned_32 := 0;
Index : Stream_Element_Offset := 1;
Buffer : Stream_Element_Array (1..Size);
Member : Controlled (Output_Block_Stream'Access);
end record;
end Block_Streams;