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|---|---|---|---|
| 1 | // | ||
| 2 | // Copyright (c) 2023 Vinnie Falco (vinnie.falco@gmail.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/cppalliance/buffers | ||
| 8 | // | ||
| 9 | |||
| 10 | #ifndef BOOST_BUFFERS_CIRCULAR_BUFFER_HPP | ||
| 11 | #define BOOST_BUFFERS_CIRCULAR_BUFFER_HPP | ||
| 12 | |||
| 13 | #include <boost/buffers/detail/config.hpp> | ||
| 14 | #include <boost/buffers/buffer_pair.hpp> | ||
| 15 | #include <boost/buffers/detail/except.hpp> | ||
| 16 | |||
| 17 | namespace boost { | ||
| 18 | namespace buffers { | ||
| 19 | |||
| 20 | /** A circular buffer. | ||
| 21 | |||
| 22 | This implements a fixed-size, circular | ||
| 23 | buffer. Buffer sequences returned from | ||
| 24 | @ref prepare and @ref data always have | ||
| 25 | length two. | ||
| 26 | */ | ||
| 27 | class circular_buffer | ||
| 28 | { | ||
| 29 | unsigned char* base_ = nullptr; | ||
| 30 | std::size_t cap_ = 0; | ||
| 31 | std::size_t in_pos_ = 0; | ||
| 32 | std::size_t in_len_ = 0; | ||
| 33 | std::size_t out_size_ = 0; | ||
| 34 | |||
| 35 | public: | ||
| 36 | /** The ConstBufferSequence used to | ||
| 37 | represent the readable bytes. | ||
| 38 | */ | ||
| 39 | using const_buffers_type = | ||
| 40 | const_buffer_pair; | ||
| 41 | |||
| 42 | /** The MutableBufferSequence used to | ||
| 43 | represent the writable bytes. | ||
| 44 | */ | ||
| 45 | using mutable_buffers_type = | ||
| 46 | mutable_buffer_pair; | ||
| 47 | |||
| 48 | /** Constructor. | ||
| 49 | */ | ||
| 50 | circular_buffer() = default; | ||
| 51 | |||
| 52 | /** Constructor. | ||
| 53 | */ | ||
| 54 | circular_buffer( | ||
| 55 | circular_buffer const&) = default; | ||
| 56 | |||
| 57 | /** Constructor. | ||
| 58 | */ | ||
| 59 | 8213 | circular_buffer( | |
| 60 | void* base, | ||
| 61 | std::size_t capacity) noexcept | ||
| 62 | 8213 | : base_(static_cast< | |
| 63 | unsigned char*>(base)) | ||
| 64 | 8213 | , cap_(capacity) | |
| 65 | { | ||
| 66 | 8213 | } | |
| 67 | |||
| 68 | /** Constructor. | ||
| 69 | */ | ||
| 70 | 2 | circular_buffer( | |
| 71 | void* base, | ||
| 72 | std::size_t capacity, | ||
| 73 | std::size_t initial_size) | ||
| 74 | 2 | : base_(static_cast< | |
| 75 | unsigned char*>(base)) | ||
| 76 | 2 | , cap_(capacity) | |
| 77 | 2 | , in_len_(initial_size) | |
| 78 | { | ||
| 79 |
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2 | if(in_len_ > capacity) |
| 80 | 1 | detail::throw_invalid_argument(); | |
| 81 | 1 | } | |
| 82 | |||
| 83 | /** Assignment. | ||
| 84 | */ | ||
| 85 | circular_buffer& operator=( | ||
| 86 | circular_buffer const&) = default; | ||
| 87 | |||
| 88 | /** Returns the number of readable bytes. | ||
| 89 | */ | ||
| 90 | std::size_t | ||
| 91 | 4119 | size() const noexcept | |
| 92 | { | ||
| 93 | 4119 | return in_len_; | |
| 94 | } | ||
| 95 | |||
| 96 | /** Returns the maximum sum of the input and | ||
| 97 | output sequence sizes. | ||
| 98 | */ | ||
| 99 | std::size_t | ||
| 100 | 4102 | max_size() const noexcept | |
| 101 | { | ||
| 102 | 4102 | return cap_; | |
| 103 | } | ||
| 104 | |||
| 105 | /** Returns the number of writable bytes. | ||
| 106 | */ | ||
| 107 | std::size_t | ||
| 108 | 8199 | capacity() const noexcept | |
| 109 | { | ||
| 110 | 8199 | return cap_ - in_len_; | |
| 111 | } | ||
| 112 | |||
| 113 | /** Returns a constant buffer sequence representing | ||
| 114 | the readable bytes. | ||
| 115 | */ | ||
| 116 | BOOST_BUFFERS_DECL | ||
| 117 | const_buffers_type | ||
| 118 | data() const noexcept; | ||
| 119 | |||
| 120 | /** Returns a mutable buffer sequence representing | ||
| 121 | the writable bytes. | ||
| 122 | |||
| 123 | All buffers sequences previously | ||
| 124 | obtained using @ref prepare become | ||
| 125 | invalid. | ||
| 126 | |||
| 127 | @param n The desired number of bytes in | ||
| 128 | the returned buffer sequence. | ||
| 129 | |||
| 130 | @throw std::length_error if @ref size() + n | ||
| 131 | exceeds @ref max_size(). | ||
| 132 | */ | ||
| 133 | BOOST_BUFFERS_DECL | ||
| 134 | mutable_buffers_type | ||
| 135 | prepare(std::size_t n); | ||
| 136 | |||
| 137 | /** Append writable bytes to the readable bytes. | ||
| 138 | |||
| 139 | Appends n bytes from the start of the | ||
| 140 | writable bytes to the end of the | ||
| 141 | readable bytes. The remainder of the | ||
| 142 | writable bytes are discarded. If n is | ||
| 143 | greater than the number of writable | ||
| 144 | bytes, all writable bytes are appended | ||
| 145 | to the readable bytes. | ||
| 146 | |||
| 147 | All buffer sequences previously obtained | ||
| 148 | using @ref prepare are invalidated. | ||
| 149 | |||
| 150 | Buffer sequences previously obtained | ||
| 151 | using @ref data remain valid. | ||
| 152 | |||
| 153 | @param n The number of bytes to append. If | ||
| 154 | this number is greater than the number | ||
| 155 | of writable bytes, all writable bytes | ||
| 156 | are appended. | ||
| 157 | */ | ||
| 158 | BOOST_BUFFERS_DECL | ||
| 159 | void | ||
| 160 | commit(std::size_t n) noexcept; | ||
| 161 | |||
| 162 | /** Remove bytes from beginning of the readable bytes. | ||
| 163 | |||
| 164 | All buffers sequences previously | ||
| 165 | obtained using @ref data are | ||
| 166 | invalidated. | ||
| 167 | |||
| 168 | Buffer sequences previously obtained | ||
| 169 | using @ref prepare remain valid. | ||
| 170 | |||
| 171 | @param n The number of bytes to remove. | ||
| 172 | If this number is greater than the | ||
| 173 | number of readable bytes, all readable | ||
| 174 | bytes are removed. | ||
| 175 | */ | ||
| 176 | BOOST_BUFFERS_DECL | ||
| 177 | void | ||
| 178 | consume(std::size_t n) noexcept; | ||
| 179 | }; | ||
| 180 | |||
| 181 | } // buffers | ||
| 182 | } // boost | ||
| 183 | |||
| 184 | #endif | ||
| 185 |