//
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// Copyright (c) 2017 Vinnie Falco (vinnie dot falco at gmail dot com)
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//
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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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//
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// Official repository: https://github.com/boostorg/beast
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//
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#ifndef BOOST_BEAST_DETAIL_VARINT_HPP
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#define BOOST_BEAST_DETAIL_VARINT_HPP
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#include <boost/static_assert.hpp>
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#include <cstdlib>
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#include <iterator>
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#include <type_traits>
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namespace boost {
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namespace beast {
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namespace detail {
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// https://developers.google.com/protocol-buffers/docs/encoding#varints
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inline
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std::size_t
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varint_size(std::size_t value)
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{
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std::size_t n = 1;
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while(value > 127)
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{
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++n;
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value /= 128;
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}
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return n;
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}
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template<class FwdIt>
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std::size_t
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varint_read(FwdIt& first)
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{
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using value_type = typename
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std::iterator_traits<FwdIt>::value_type;
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BOOST_STATIC_ASSERT(
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std::is_integral<value_type>::value &&
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sizeof(value_type) == 1);
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std::size_t value = 0;
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std::size_t factor = 1;
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while((*first & 0x80) != 0)
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{
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value += (*first++ & 0x7f) * factor;
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factor *= 128;
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}
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value += *first++ * factor;
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return value;
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}
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template<class FwdIt>
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void
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varint_write(FwdIt& first, std::size_t value)
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{
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using value_type = typename
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std::iterator_traits<FwdIt>::value_type;
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BOOST_STATIC_ASSERT(
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std::is_integral<value_type>::value &&
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sizeof(value_type) == 1);
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while(value > 127)
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{
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*first++ = static_cast<value_type>(
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0x80 | value);
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value /= 128;
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}
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*first++ = static_cast<value_type>(value);
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}
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} // detail
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} // beast
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} // boost
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#endif
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