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--  Just for fun, playing with the old Zip "Reduce" format...
--
--  "Reduce" combines the LZ77 method with a probabilistic
--  predictor using a Markov chain.
--
--  The format has a single block, then a single matrix,
--  for the whole data to be compressed :-(.
--
--  NB: this compressor works in two passes, the first pass
--     serving to compute the exact optimal Markov matrix for the whole
--     data to be compressed. Hence, it is slow. However,
--     we cache the last n=LZ_cache_size bytes compressed by LZ77.
--     The resulting compression is optimal within the constraints of the
--     "Reduce" format (one block, poor encoding of compressed data and of the
--     compression structure itself (the Markov matrix)).
--
--  Author: G. de Montmollin, January 2009
--
--  Legal licensing note:

--  Copyright (c) 2009 .. 2023 Gautier de Montmollin
--  SWITZERLAND

--  Permission is hereby granted, free of charge, to any person obtaining a copy
--  of this software and associated documentation files (the "Software"), to deal
--  in the Software without restriction, including without limitation the rights
--  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
--  copies of the Software, and to permit persons to whom the Software is
--  furnished to do so, subject to the following conditions:

--  The above copyright notice and this permission notice shall be included in
--  all copies or substantial portions of the Software.

--  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
--  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
--  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
--  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
--  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
--  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
--  THE SOFTWARE.

--  NB: this is the MIT License, as found on the site
--  http://www.opensource.org/licenses/mit-license.php

with Zip.CRC_Crypto;

private procedure Zip.Compress.Reduce
  (input,
   output           : in out Zip_Streams.Root_Zipstream_Type'Class;
   input_size_known :        Boolean;
   input_size       :        Zip_64_Data_Size_Type;  --  ignored if unknown
   feedback         :        Feedback_Proc;
   method           :        Reduction_Method;
   CRC              : in out Interfaces.Unsigned_32;  --  only updated here
   crypto           : in out CRC_Crypto.Crypto_pack;
   output_size      :    out Zip_64_Data_Size_Type;
   compression_ok   :    out Boolean);  --  indicates when compressed <= uncompressed