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diff --git a/backend/genesys/buffer.h b/backend/genesys/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_BUFFER_H
+#define BACKEND_GENESYS_BUFFER_H
+
+#include <vector>
+#include <cstddef>
+#include <cstdint>
+
+namespace genesys {
+
+/*  A FIFO buffer. Note, that this is _not_ a ringbuffer.
+    if we need a block which does not fit at the end of our available data,
+    we move the available data to the beginning.
+*/
+struct Genesys_Buffer
+{
+    Genesys_Buffer() = default;
+
+    std::size_t size() const { return buffer_.size(); }
+    std::size_t avail() const { return avail_; }
+    std::size_t pos() const { return pos_; }
+
+    // TODO: refactor code that uses this function to no longer use it
+    void set_pos(std::size_t pos) { pos_ = pos; }
+
+    void alloc(std::size_t size);
+    void clear();
+
+    void reset();
+
+    std::uint8_t* get_write_pos(std::size_t size);
+    std::uint8_t* get_read_pos(); // TODO: mark as const
+
+    void produce(std::size_t size);
+    void consume(std::size_t size);
+
+private:
+    std::vector<std::uint8_t> buffer_;
+    // current position in read buffer
+    std::size_t pos_ = 0;
+    // data bytes currently in buffer
+    std::size_t avail_ = 0;
+};
+
+} // namespace genesys
+
+#endif // BACKEND_GENESYS_BUFFER_H