1 /* sane - Scanner Access Now Easy. 2 3 Copyright (C) 2019 Povilas Kanapickas <povilas@radix.lt> 4 5 This file is part of the SANE package. 6 7 This program is free software; you can redistribute it and/or 8 modify it under the terms of the GNU General Public License as 9 published by the Free Software Foundation; either version 2 of the 10 License, or (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, but 13 WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <https://www.gnu.org/licenses/>. 19 20 As a special exception, the authors of SANE give permission for 21 additional uses of the libraries contained in this release of SANE. 22 23 The exception is that, if you link a SANE library with other files 24 to produce an executable, this does not by itself cause the 25 resulting executable to be covered by the GNU General Public 26 License. Your use of that executable is in no way restricted on 27 account of linking the SANE library code into it. 28 29 This exception does not, however, invalidate any other reasons why 30 the executable file might be covered by the GNU General Public 31 License. 32 33 If you submit changes to SANE to the maintainers to be included in 34 a subsequent release, you agree by submitting the changes that 35 those changes may be distributed with this exception intact. 36 37 If you write modifications of your own for SANE, it is your choice 38 whether to permit this exception to apply to your modifications. 39 If you do not wish that, delete this exception notice. 40 */ 41 42 #ifndef BACKEND_GENESYS_LINE_BUFFER_H 43 #define BACKEND_GENESYS_LINE_BUFFER_H 44 45 #include "error.h" 46 47 #include <algorithm> 48 #include <cstdint> 49 #include <cstddef> 50 #include <vector> 51 52 namespace genesys { 53 54 class RowBuffer 55 { 56 public: RowBuffer(std::size_t line_bytes)57 RowBuffer(std::size_t line_bytes) : row_bytes_{line_bytes} {} 58 RowBuffer(const RowBuffer&) = default; 59 RowBuffer& operator=(const RowBuffer&) = default; 60 ~RowBuffer() = default; 61 get_row_ptr(std::size_t y)62 const std::uint8_t* get_row_ptr(std::size_t y) const 63 { 64 if (y >= height()) { 65 throw SaneException("y %zu is out of range", y); 66 } 67 return data_.data() + row_bytes_ * get_row_index(y); 68 } 69 get_row_ptr(std::size_t y)70 std::uint8_t* get_row_ptr(std::size_t y) 71 { 72 if (y >= height()) { 73 throw SaneException("y %zu is out of range", y); 74 } 75 return data_.data() + row_bytes_ * get_row_index(y); 76 } 77 get_front_row_ptr()78 const std::uint8_t* get_front_row_ptr() const { return get_row_ptr(0); } get_front_row_ptr()79 std::uint8_t* get_front_row_ptr() { return get_row_ptr(0); } get_back_row_ptr()80 const std::uint8_t* get_back_row_ptr() const { return get_row_ptr(height() - 1); } get_back_row_ptr()81 std::uint8_t* get_back_row_ptr() { return get_row_ptr(height() - 1); } 82 empty()83 bool empty() const { return is_linear_ && first_ == last_; } 84 full()85 bool full() 86 { 87 if (is_linear_) { 88 return last_ == buffer_end_; 89 } 90 return first_ == last_; 91 } 92 is_linear()93 bool is_linear() const { return is_linear_; } 94 linearize()95 void linearize() 96 { 97 if (!is_linear_) { 98 std::rotate(data_.begin(), data_.begin() + row_bytes_ * first_, data_.end()); 99 last_ = height(); 100 first_ = 0; 101 is_linear_ = true; 102 } 103 } 104 pop_front()105 void pop_front() 106 { 107 if (empty()) { 108 throw SaneException("Trying to pop out of empty() line buffer"); 109 } 110 111 first_++; 112 if (first_ == last_) { 113 first_ = 0; 114 last_ = 0; 115 is_linear_ = true; 116 } else if (first_ == buffer_end_) { 117 first_ = 0; 118 is_linear_ = true; 119 } 120 } 121 push_front()122 void push_front() 123 { 124 if (height() + 1 >= height_capacity()) { 125 ensure_capacity(std::max<std::size_t>(1, height() * 2)); 126 } 127 128 if (first_ == 0) { 129 is_linear_ = false; 130 first_ = buffer_end_; 131 } 132 first_--; 133 } 134 pop_back()135 void pop_back() 136 { 137 if (empty()) { 138 throw SaneException("Trying to pop out of empty() line buffer"); 139 } 140 if (last_ == 0) { 141 last_ = buffer_end_; 142 is_linear_ = true; 143 } 144 last_--; 145 if (first_ == last_) { 146 first_ = 0; 147 last_ = 0; 148 is_linear_ = true; 149 } 150 } 151 push_back()152 void push_back() 153 { 154 if (height() + 1 >= height_capacity()) { 155 ensure_capacity(std::max<std::size_t>(1, height() * 2)); 156 } 157 158 if (last_ == buffer_end_) { 159 is_linear_ = false; 160 last_ = 0; 161 } 162 last_++; 163 } 164 row_bytes()165 std::size_t row_bytes() const { return row_bytes_; } 166 height()167 std::size_t height() const 168 { 169 if (!is_linear_) { 170 return last_ + buffer_end_ - first_; 171 } 172 return last_ - first_; 173 } 174 height_capacity()175 std::size_t height_capacity() const { return buffer_end_; } 176 clear()177 void clear() 178 { 179 first_ = 0; 180 last_ = 0; 181 } 182 183 private: get_row_index(std::size_t index)184 std::size_t get_row_index(std::size_t index) const 185 { 186 if (index >= buffer_end_ - first_) { 187 return index - (buffer_end_ - first_); 188 } 189 return index + first_; 190 } 191 ensure_capacity(std::size_t capacity)192 void ensure_capacity(std::size_t capacity) 193 { 194 if (capacity < height_capacity()) 195 return; 196 linearize(); 197 data_.resize(capacity * row_bytes_); 198 buffer_end_ = capacity; 199 } 200 201 private: 202 std::size_t row_bytes_ = 0; 203 std::size_t first_ = 0; 204 std::size_t last_ = 0; 205 std::size_t buffer_end_ = 0; 206 bool is_linear_ = true; 207 std::vector<std::uint8_t> data_; 208 }; 209 210 } // namespace genesys 211 212 #endif // BACKEND_GENESYS_LINE_BUFFER_H 213