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       1              : //
       2              : // Copyright (c) 2021 Vinnie Falco (vinnie.falco@gmail.com)
       3              : // Copyright (c) 2024 Christian Mazakas
       4              : //
       5              : // Distributed under the Boost Software License, Version 1.0. (See accompanying
       6              : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       7              : //
       8              : // Official repository: https://github.com/cppalliance/http_proto
       9              : //
      10              : 
      11              : #ifndef BOOST_HTTP_PROTO_SERVICE_ZLIB_SERVICE_HPP
      12              : #define BOOST_HTTP_PROTO_SERVICE_ZLIB_SERVICE_HPP
      13              : 
      14              : #include <boost/http_proto/detail/config.hpp>
      15              : #include <boost/http_proto/context.hpp>
      16              : #include <boost/http_proto/service/service.hpp>
      17              : 
      18              : namespace boost {
      19              : namespace http_proto {
      20              : namespace zlib {
      21              : 
      22              : struct decoder_config
      23              : {
      24              :     unsigned max_window_bits = 15;
      25              :     unsigned mem_level = 8;
      26              : };
      27              : 
      28              : //------------------------------------------------
      29              : 
      30              : constexpr
      31              : inline
      32              : std::size_t
      33           24 : encoding_size_hint(decoder_config cfg = {}) noexcept
      34              : {
      35              :     // from: https://www.zlib.net/zlib_tech.html
      36              :     //
      37              :     // Memory Footprint
      38              :     //
      39              :     // zlib's memory footprint can also be specified fairly
      40              :     // precisely. It is larger for compression than for
      41              :     // decompression, and the exact requirements depend on
      42              :     // how the library was compiled.
      43              :     //
      44              :     // The memory requirements for compression depend on two
      45              :     // parameters, windowBits and memLevel:
      46              :     //     deflate memory usage (bytes) = (1 << (windowBits+2)) + (1 << (memLevel+9)) + 6 KB
      47              :     return
      48           24 :         (1 << (cfg.max_window_bits + 2)) +
      49           24 :         (1 << (cfg.mem_level + 9)) +
      50           24 :         (6 * 1024);
      51              : }
      52              : 
      53              : void BOOST_HTTP_PROTO_ZLIB_DECL
      54              : install_deflate_encoder(context& ctx);
      55              : 
      56              : } // zlib
      57              : } // http_proto
      58              : } // boost
      59              : 
      60              : #endif