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------------------------------------------------------------------------------
-- G N A T C O L L --
-- --
-- Copyright (C) 2019, AdaCore --
-- --
-- This library is free software; you can redistribute it and/or modify it --
-- under terms of the GNU General Public License as published by the Free --
-- Software Foundation; either version 3, 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 MERCHAN- --
-- TABILITY 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/>. --
-- --
------------------------------------------------------------------------------
-- This package provides binding to LZMA compression/decompression
with Ada.Finalization;
limited with GNATCOLL.Coders.LZMA.Thin;
package GNATCOLL.Coders.LZMA is
type Coder_Type is
new Ada.Finalization.Limited_Controlled and Coder_Interface
with private;
type Preset_Type is new Integer range 0 .. 9;
type Check_Type is
(Check_None,
-- No Check is calculated.
-- Size of the Check field: 0 bytes
Check_CRC32,
-- CRC32 using the polynomial from the IEEE 802.3 standard
-- Size of the Check field: 4 bytes
Check_CRC64,
-- CRC64 using the polynomial from the ECMA-182 standard
-- Size of the Check field: 8 bytes
Check_SHA256
-- SHA-256
-- Size of the Check field: 32 bytes
);
-- Type of the integrity check (Check ID)
--
-- The .xz format supports multiple types of checks that are calculated
-- from the uncompressed data. They vary in both speed and ability to
-- detect errors.
procedure Encoder
(Coder : in out Coder_Type;
Preset : Preset_Type := 6;
Extreme : Boolean := False;
Threads : Positive := 1;
Timeout : Duration := 0.0;
Check : Check_Type := Check_CRC64);
-- Initializes compression coder.
-- Preset is compression level from 0 to 9 roughly defining compression
-- quality and level of memory usage. Bigger number means better
-- compression but consumes more time and memory.
-- Extreme - Modify the compression preset (0 .. 9) to achieve a
-- slightly better compression ratio without increasing memory usage
-- of the compressor or decompressor. The downside is that the compression
-- time will increase dramatically (it can easily double).
-- Threads is number of threads to use in compression. Faster compression
-- can be reached with more CPU and memory usage. If computer has only one
-- CPU then this option provides no gain.
-- Timeout has meaning only when Threads parameter is more than 1. It is
-- to allow Transcode to return early. Multithreading can make liblzma to
-- consume input and produce output in a very bursty way: it may first read
-- a lot of input to fill internal buffers, then no input or output occurs
-- for a while. To avoid very long blocking times in Transcode, a timeout
-- may be set here. If Transcode would block longer than this time, it will
-- return with not taken data from In_Data and no results in Out_Data.
-- If long blocking times are fine for you, set timeout to a special
-- value of 0, which will disable the timeout mechanism and will make
-- Transcode block until all the input is consumed or the output buffer has
-- been filled. Even with a timeout, Transcode might sometimes take
-- somewhat long time to return. No timing guarantees are made.
-- Check is integrity check type to use.
procedure Auto_Decoder (Coder : in out Coder_Type);
overriding function Is_Open (Coder : Coder_Type) return Boolean;
-- Indicates that coder is ready to transcode data, i.e either Easy_Encoder
-- or Auto_Decoder called.
overriding procedure Transcode
(Coder : in out Coder_Type;
In_Data : Stream_Element_Array;
In_Last : out Stream_Element_Offset;
Out_Data : out Stream_Element_Array;
Out_Last : out Stream_Element_Offset;
Flush : Flush_Mode := No_Flush);
-- Transcodes data from In_Data to Out_Data.
-- In_Last is the index of last element from In_Data accepted by
-- the Coder.
-- Out_Last is the index of the last element written to Out_Data.
-- To tell the Coder that incoming data is complete pass Finish as the
-- Flush parameter and call Transcoder with empty In_Data until Stream_End
-- routine indicates end of stream.
overriding function Total_In
(Coder : Coder_Type) return Stream_Element_Count;
-- Returns the total amount of input data sent into the coder
overriding function Total_Out
(Coder : Coder_Type) return Stream_Element_Count;
-- Returns the total amount of output data taken from the coder
overriding function Finished (Coder : Coder_Type) return Boolean;
-- Indicates that incoming data stream is complete and all internally
-- processed data is out of coder.
overriding procedure Close (Coder : in out Coder_Type);
-- Frees internal coder memory allocations. Note that coder is derived from
-- Limited_Controlled and will free all memory automatically on
-- finalization.
LZMA_Error : exception;
private
type LZMA_Stream_Access is access all Thin.lzma_stream;
type Coder_Type is
new Ada.Finalization.Limited_Controlled and Coder_Interface
with record
Stream : LZMA_Stream_Access;
Finished : Boolean := False;
end record;
overriding procedure Finalize (Coder : in out Coder_Type);
end GNATCOLL.Coders.LZMA;
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