63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
// Copyright (c) 2012-2013 The Cryptonote developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#pragma once
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#include <limits>
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#include <type_traits>
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#include <utility>
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#include <sstream>
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#include <string>
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namespace tools {
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template<typename OutputIt, typename T>
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typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value, void>::type
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write_varint(OutputIt &&dest, T i) {
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while (i >= 0x80) {
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*dest++ = (static_cast<char>(i) & 0x7f) | 0x80;
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i >>= 7;
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}
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*dest++ = static_cast<char>(i);
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}
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template<typename t_type>
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std::string get_varint_data(const t_type& v)
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{
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std::stringstream ss;
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write_varint(std::ostreambuf_iterator<char>(ss), v);
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return ss.str();
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}
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template<int bits, typename InputIt, typename T>
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typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value && 0 <= bits && bits <= std::numeric_limits<T>::digits, int>::type
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read_varint(InputIt &&first, InputIt &&last, T &i) {
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int read = 0;
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i = 0;
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for (int shift = 0;; shift += 7) {
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if (first == last) {
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return read; // End of input.
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}
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unsigned char byte = *first++;
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++read;
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if (shift + 7 >= bits && byte >= 1 << (bits - shift)) {
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return -1; // Overflow.
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}
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if (byte == 0 && shift != 0) {
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return -2; // Non-canonical representation.
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}
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i |= static_cast<T>(byte & 0x7f) << shift;
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if ((byte & 0x80) == 0) {
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break;
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}
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}
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return read;
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}
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template<typename InputIt, typename T>
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int read_varint(InputIt &&first, InputIt &&last, T &i) {
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return read_varint<std::numeric_limits<T>::digits, InputIt, T>(std::move(first), std::move(last), i);
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}
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}
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