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diff --git a/backend/genesys/image_buffer.h b/backend/genesys/image_buffer.h
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+/* sane - Scanner Access Now Easy.
+
+   Copyright (C) 2019 Povilas Kanapickas <povilas@radix.lt>
+
+   This file is part of the SANE package.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+   MA 02111-1307, USA.
+
+   As a special exception, the authors of SANE give permission for
+   additional uses of the libraries contained in this release of SANE.
+
+   The exception is that, if you link a SANE library with other files
+   to produce an executable, this does not by itself cause the
+   resulting executable to be covered by the GNU General Public
+   License.  Your use of that executable is in no way restricted on
+   account of linking the SANE library code into it.
+
+   This exception does not, however, invalidate any other reasons why
+   the executable file might be covered by the GNU General Public
+   License.
+
+   If you submit changes to SANE to the maintainers to be included in
+   a subsequent release, you agree by submitting the changes that
+   those changes may be distributed with this exception intact.
+
+   If you write modifications of your own for SANE, it is your choice
+   whether to permit this exception to apply to your modifications.
+   If you do not wish that, delete this exception notice.
+*/
+
+#ifndef BACKEND_GENESYS_IMAGE_BUFFER_H
+#define BACKEND_GENESYS_IMAGE_BUFFER_H
+
+#include "enums.h"
+#include "row_buffer.h"
+#include <algorithm>
+#include <functional>
+
+namespace genesys {
+
+// This class allows reading from row-based source in smaller or larger chunks of data
+class ImageBuffer
+{
+public:
+    using ProducerCallback = std::function<bool(std::size_t size, std::uint8_t* out_data)>;
+
+    ImageBuffer() {}
+    ImageBuffer(std::size_t size, ProducerCallback producer);
+
+    std::size_t size() const { return size_; }
+    std::size_t available() const { return size_ - buffer_offset_; }
+
+    bool get_data(std::size_t size, std::uint8_t* out_data);
+
+private:
+    ProducerCallback producer_;
+    std::size_t size_ = 0;
+
+    std::size_t buffer_offset_ = 0;
+    std::vector<std::uint8_t> buffer_;
+};
+
+class FakeBufferModel
+{
+public:
+    FakeBufferModel() {}
+
+    void push_step(std::size_t buffer_size, std::size_t row_bytes);
+
+    std::size_t available_space() const;
+
+    void simulate_read(std::size_t size);
+
+private:
+    std::vector<std::size_t> sizes_;
+    std::vector<std::size_t> available_sizes_;
+    std::vector<std::size_t> row_bytes_;
+};
+
+// This class is similar to ImageBuffer, but preserves historical peculiarities of buffer handling
+// in the backend to preserve exact behavior
+class ImageBufferGenesysUsb
+{
+public:
+    using ProducerCallback = std::function<void(std::size_t size, std::uint8_t* out_data)>;
+
+    ImageBufferGenesysUsb() {}
+    ImageBufferGenesysUsb(std::size_t total_size, const FakeBufferModel& buffer_model,
+                          ProducerCallback producer);
+
+    std::size_t remaining_size() const { return remaining_size_; }
+
+    void set_remaining_size(std::size_t bytes) { remaining_size_ = bytes; }
+
+    std::size_t available() const { return buffer_end_ - buffer_offset_; }
+
+    bool get_data(std::size_t size, std::uint8_t* out_data);
+
+private:
+
+    std::size_t get_read_size();
+
+    std::size_t remaining_size_ = 0;
+
+    std::size_t buffer_offset_ = 0;
+    std::size_t buffer_end_ = 0;
+    std::vector<std::uint8_t> buffer_;
+
+    FakeBufferModel buffer_model_;
+
+    ProducerCallback producer_;
+};
+
+} // namespace genesys
+
+#endif // BACKEND_GENESYS_IMAGE_BUFFER_H