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   1  --  The "Deflate" method combines the LZ77 compression
   2  --  method with some Huffman encoding gymnastics.
   3  --
   4  --  See body for technical details.
   5  --
   6  --  Author: G. de Montmollin, February 2011 and later
   7  --
   8  --  Legal licensing note:
   9  
  10  --  Copyright (c) 2011 .. 2023 Gautier de Montmollin
  11  --  SWITZERLAND
  12  
  13  --  Permission is hereby granted, free of charge, to any person obtaining a copy
  14  --  of this software and associated documentation files (the "Software"), to deal
  15  --  in the Software without restriction, including without limitation the rights
  16  --  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  17  --  copies of the Software, and to permit persons to whom the Software is
  18  --  furnished to do so, subject to the following conditions:
  19  
  20  --  The above copyright notice and this permission notice shall be included in
  21  --  all copies or substantial portions of the Software.
  22  
  23  --  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  24  --  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  25  --  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  26  --  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  27  --  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  28  --  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  29  --  THE SOFTWARE.
  30  
  31  --  NB: this is the MIT License, as found on the site
  32  --  http://www.opensource.org/licenses/mit-license.php
  33  
  34  with Zip.CRC_Crypto;
  35  
  36  private procedure Zip.Compress.Deflate
  37    (input,
  38     output           : in out Zip_Streams.Root_Zipstream_Type'Class;
  39     input_size_known :        Boolean;
  40     input_size       :        Zip_64_Data_Size_Type;  --  ignored if unknown
  41     feedback         :        Feedback_Proc;
  42     method           :        Deflation_Method;
  43     CRC              : in out Interfaces.Unsigned_32;  --  only updated here
  44     crypto           : in out CRC_Crypto.Crypto_pack;
  45     output_size      :    out Zip_64_Data_Size_Type;
  46     compression_ok   :    out Boolean);  --  indicates when compressed <= uncompressed