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
46namespace boost {
47namespace beast {
48namespace zlib {
49namespace detail {
50
51class 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
59public:
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(dest: out, src: &p_[i_ - pos], n: n);
98 return;
99 }
100 auto i = ((i_ - pos) + capacity_) % capacity_;
101 auto m = capacity_ - i;
102 if(n <= m)
103 {
104 std::memcpy(dest: out, src: &p_[i], n: n);
105 return;
106 }
107 std::memcpy(dest: out, src: &p_[i], n: m);
108 out += m;
109 std::memcpy(dest: out, src: &p_[0], n: 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[]>(size: capacity_);
118 if(n >= capacity_)
119 {
120 i_ = 0;
121 size_ = capacity_;
122 std::memcpy(dest: &p_[0], src: in + (n - size_), n: size_);
123 return;
124 }
125 if(i_ + n <= capacity_)
126 {
127 std::memcpy(dest: &p_[i_], src: in, n: 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(dest: &p_[i_], src: in, n: m);
139 in += m;
140 i_ = static_cast<std::uint16_t>(n - m);
141 std::memcpy(dest: &p_[0], src: in, n: i_);
142 size_ = capacity_;
143 }
144};
145
146} // detail
147} // zlib
148} // beast
149} // boost
150
151#endif
152

source code of boost/libs/beast/include/boost/beast/zlib/detail/window.hpp