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

   1 //
   2 // Copyright (c) 2016-2017 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     void
  82     read(std::uint8_t* out, std::size_t pos, std::size_t n);
  83
  84     template<class = void>
  85     void
  86     write(std::uint8_t const* in, std::size_t n);
  87 };
  88
  89 inline
  90 void
  91 window::
  92 reset(int bits)
  93 {
  94     if(bits_ != bits)
  95     {
  96         p_.reset();
  97         bits_ = static_cast<std::uint8_t>(bits);
  98         capacity_ = 1U << bits_;
  99     }
 100     i_ = 0;
 101     size_ = 0;
 102 }
 103
 104 inline
 105 void
 106 window::
 107 read(std::uint8_t* out, std::size_t pos, std::size_t n)
 108 {
 109     if(i_ >= size_)
 110     {
 111         // window is contiguous
 112         std::memcpy(out, &p_[i_ - pos], n);
 113         return;
 114     }
 115     auto i = ((i_ - pos) + capacity_) % capacity_;
 116     auto m = capacity_ - i;
 117     if(n <= m)
 118     {
 119         std::memcpy(out, &p_[i], n);
 120         return;
 121     }
 122     std::memcpy(out, &p_[i], m);
 123     out += m;
 124     std::memcpy(out, &p_[0], n - m);
 125 }
 126
 127 template<class>
 128 void
 129 window::
 130 write(std::uint8_t const* in, std::size_t n)
 131 {
 132     if(! p_)
 133         p_ = boost::make_unique<
 134             std::uint8_t[]>(capacity_);
 135     if(n >= capacity_)
 136     {
 137         i_ = 0;
 138         size_ = capacity_;
 139         std::memcpy(&p_[0], in + (n - size_), size_);
 140         return;
 141     }
 142     if(i_ + n <= capacity_)
 143     {
 144         std::memcpy(&p_[i_], in, n);
 145         if(size_ >= capacity_ - n)
 146             size_ = capacity_;
 147         else
 148             size_ = static_cast<std::uint16_t>(size_ + n);
 149
 150         i_ = static_cast<std::uint16_t>(
 151             (i_ + n) % capacity_);
 152         return;
 153     }
 154     auto m = capacity_ - i_;
 155     std::memcpy(&p_[i_], in, m);
 156     in += m;
 157     i_ = static_cast<std::uint16_t>(n - m);
 158     std::memcpy(&p_[0], in, i_);
 159     size_ = capacity_;
 160 }
 161
 162 } // detail
 163 } // zlib
 164 } // beast
 165 } // boost
 166
 167 #endif