ceph/src/boost/boost/beast/zlib/detail/window.hpp

   1 //
   2 // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // Official repository: https://github.com/boostorg/beast
   8 //
   9 // This is a derivative work based on Zlib, copyright below:
  10 /*
  11     Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
  12
  13     This software is provided 'as-is', without any express or implied
  14     warranty.  In no event will the authors be held liable for any damages
  15     arising from the use of this software.
  16
  17     Permission is granted to anyone to use this software for any purpose,
  18     including commercial applications, and to alter it and redistribute it
  19     freely, subject to the following restrictions:
  20
  21     1. The origin of this software must not be misrepresented; you must not
  22        claim that you wrote the original software. If you use this software
  23        in a product, an acknowledgment in the product documentation would be
  24        appreciated but is not required.
  25     2. Altered source versions must be plainly marked as such, and must not be
  26        misrepresented as being the original software.
  27     3. This notice may not be removed or altered from any source distribution.
  28
  29     Jean-loup Gailly        Mark Adler
  30     jloup@gzip.org          madler@alumni.caltech.edu
  31
  32     The data format used by the zlib library is described by RFCs (Request for
  33     Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
  34     (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
  35 */
  36
  37 #ifndef BOOST_BEAST_ZLIB_DETAIL_WINDOW_HPP
  38 #define BOOST_BEAST_ZLIB_DETAIL_WINDOW_HPP
  39
  40 #include <boost/assert.hpp>
  41 #include <boost/make_unique.hpp>
  42 #include <cstdint>
  43 #include <cstring>
  44 #include <memory>
  45
  46 namespace boost {
  47 namespace beast {
  48 namespace zlib {
  49 namespace detail {
  50
  51 class window
  52 {
  53     std::unique_ptr<std::uint8_t[]> p_;
  54     std::uint16_t i_ = 0;
  55     std::uint16_t size_ = 0;
  56     std::uint16_t capacity_ = 0;
  57     std::uint8_t bits_ = 0;
  58
  59 public:
  60     int
  61     bits() const
  62     {
  63         return bits_;
  64     }
  65
  66     unsigned
  67     capacity() const
  68     {
  69         return capacity_;
  70     }
  71
  72     unsigned
  73     size() const
  74     {
  75         return size_;
  76     }
  77
  78     void
  79     reset(int bits)
  80     {
  81         if(bits_ != bits)
  82         {
  83             p_.reset();
  84             bits_ = static_cast<std::uint8_t>(bits);
  85             capacity_ = 1U << bits_;
  86         }
  87         i_ = 0;
  88         size_ = 0;
  89     }
  90
  91     void
  92     read(std::uint8_t* out, std::size_t pos, std::size_t n)
  93     {
  94         if(i_ >= size_)
  95         {
  96             // window is contiguous
  97             std::memcpy(out, &p_[i_ - pos], n);
  98             return;
  99         }
 100         auto i = ((i_ - pos) + capacity_) % capacity_;
 101         auto m = capacity_ - i;
 102         if(n <= m)
 103         {
 104             std::memcpy(out, &p_[i], n);
 105             return;
 106         }
 107         std::memcpy(out, &p_[i], m);
 108         out += m;
 109         std::memcpy(out, &p_[0], n - m);
 110     }
 111
 112     void
 113     write(std::uint8_t const* in, std::size_t n)
 114     {
 115         if(! p_)
 116             p_ = boost::make_unique<
 117                 std::uint8_t[]>(capacity_);
 118         if(n >= capacity_)
 119         {
 120             i_ = 0;
 121             size_ = capacity_;
 122             std::memcpy(&p_[0], in + (n - size_), size_);
 123             return;
 124         }
 125         if(i_ + n <= capacity_)
 126         {
 127             std::memcpy(&p_[i_], in, n);
 128             if(size_ >= capacity_ - n)
 129                 size_ = capacity_;
 130             else
 131                 size_ = static_cast<std::uint16_t>(size_ + n);
 132
 133             i_ = static_cast<std::uint16_t>(
 134                 (i_ + n) % capacity_);
 135             return;
 136         }
 137         auto m = capacity_ - i_;
 138         std::memcpy(&p_[i_], in, m);
 139         in += m;
 140         i_ = static_cast<std::uint16_t>(n - m);
 141         std::memcpy(&p_[0], in, i_);
 142         size_ = capacity_;
 143     }
 144 };
 145
 146 } // detail
 147 } // zlib
 148 } // beast
 149 } // boost
 150
 151 #endif