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//
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//
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// Copyright (c) 2023 Vinnie Falco (vinnie.falco@gmail.com)
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// Copyright (c) 2023 Vinnie Falco (vinnie.falco@gmail.com)
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//
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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//
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// Official repository: https://github.com/cppalliance/capy
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// Official repository: https://github.com/cppalliance/capy
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//
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//
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#ifndef BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
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#ifndef BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
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#define BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
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#define BOOST_CAPY_BUFFERS_BUFFER_COPY_HPP
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#include <boost/capy/detail/config.hpp>
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#include <boost/capy/detail/config.hpp>
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#include <boost/capy/buffers.hpp>
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#include <boost/capy/buffers.hpp>
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#include <cstring>
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#include <cstring>
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#include <utility>
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#include <utility>
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namespace boost {
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namespace boost {
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namespace capy {
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namespace capy {
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/** Copy the contents of a buffer sequence into another buffer sequence.
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/** Copy the contents of a buffer sequence into another buffer sequence.
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    This function copies bytes from the constant buffer sequence `src` into
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    This function copies bytes from the constant buffer sequence `src` into
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    the mutable buffer sequence `dest`, stopping when any limit is reached.
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    the mutable buffer sequence `dest`, stopping when any limit is reached.
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    @par Constraints
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    @par Constraints
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    @code
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    @code
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    MutableBufferSequence<decltype(dest)> &&
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    MutableBufferSequence<decltype(dest)> &&
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    ConstBufferSequence<decltype(src)>
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    ConstBufferSequence<decltype(src)>
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    @endcode
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    @endcode
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    @return The number of bytes copied, equal to
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    @return The number of bytes copied, equal to
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    `std::min(size(dest), size(src), at_most)`.
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    `std::min(size(dest), size(src), at_most)`.
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    @param dest The destination buffer sequence.
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    @param dest The destination buffer sequence.
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    @param src The source buffer sequence.
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    @param src The source buffer sequence.
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    @param at_most The maximum bytes to copy. Default copies all available.
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    @param at_most The maximum bytes to copy. Default copies all available.
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*/
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*/
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constexpr struct buffer_copy_mrdocs_workaround_t
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constexpr struct buffer_copy_mrdocs_workaround_t
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{
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{
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    template<
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    template<
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        MutableBufferSequence MB,
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        MutableBufferSequence MB,
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        ConstBufferSequence CB>
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        ConstBufferSequence CB>
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    std::size_t
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    std::size_t
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    operator()(
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    operator()(
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        MB const& dest,
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        MB const& dest,
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        CB const& src,
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        CB const& src,
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        std::size_t at_most = std::size_t(-1)) const noexcept
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        std::size_t at_most = std::size_t(-1)) const noexcept
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    {
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    {
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        std::size_t total = 0;
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        std::size_t total = 0;
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        std::size_t pos0 = 0;
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        std::size_t pos0 = 0;
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        std::size_t pos1 = 0;
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        std::size_t pos1 = 0;
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        auto const end0 = end(src);
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        auto const end0 = end(src);
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        auto const end1 = end(dest);
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        auto const end1 = end(dest);
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        auto it0 = begin(src);
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        auto it0 = begin(src);
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        auto it1 = begin(dest);
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        auto it1 = begin(dest);
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        while(
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        while(
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            total < at_most &&
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            total < at_most &&
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            it0 != end0 &&
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            it0 != end0 &&
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            it1 != end1)
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            it1 != end1)
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        {
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        {
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            const_buffer b0 = *it0;
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            const_buffer b0 = *it0;
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            mutable_buffer b1 = *it1;
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            mutable_buffer b1 = *it1;
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            b0 += pos0;
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            b0 += pos0;
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            b1 += pos1;
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            b1 += pos1;
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            std::size_t const amount =
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            std::size_t const amount =
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            [&]
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            [&]
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            {
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            {
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                std::size_t n = b0.size();
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                std::size_t n = b0.size();
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                if( n > b1.size())
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                if( n > b1.size())
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                    n = b1.size();
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                    n = b1.size();
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                if( n > at_most - total)
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                if( n > at_most - total)
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                    n = at_most - total;
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                    n = at_most - total;
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                if(n != 0)
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                if(n != 0)
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                    std::memcpy(
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                    std::memcpy(
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                        b1.data(),
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                        b1.data(),
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                        b0.data(),
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                        b0.data(),
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                        n);
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                        n);
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                return n;
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                return n;
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            }();
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            }();
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            total += amount;
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            total += amount;
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            if(amount == b1.size())
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            if(amount == b1.size())
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            {
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            {
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                ++it1;
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                ++it1;
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                pos1 = 0;
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                pos1 = 0;
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            }
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            }
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            else
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            else
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            {
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            {
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                pos1 += amount;
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                pos1 += amount;
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            }
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            }
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            if(amount == b0.size())
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            if(amount == b0.size())
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            {
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            {
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                ++it0;
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                ++it0;
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                pos0 = 0;
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                pos0 = 0;
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            }
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            }
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            else
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            else
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            {
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            {
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                pos0 += amount;
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                pos0 += amount;
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            }
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            }
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        }
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        }
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        return total;
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        return total;
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    }
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    }
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} buffer_copy {};
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} buffer_copy {};
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} // capy
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} // capy
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} // boost
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} // boost
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#endif
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#endif