141 lines
4.4 KiB
C++
141 lines
4.4 KiB
C++
/*
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Copyright (c) 2016, Arvid Norberg
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "libtorrent/sha1_hash.hpp"
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#include "libtorrent/hex.hpp" // to_hex, from_hex
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#if TORRENT_USE_IOSTREAM
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#include <iostream>
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#include <iomanip>
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#endif // TORRENT_USE_IOSTREAM
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namespace libtorrent
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{
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#if TORRENT_USE_IOSTREAM
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// print a sha1_hash object to an ostream as 40 hexadecimal digits
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std::ostream& operator<<(std::ostream& os, sha1_hash const& peer)
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{
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return os << aux::to_hex(peer);
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}
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// read 40 hexadecimal digits from an istream into a sha1_hash
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std::istream& operator>>(std::istream& is, sha1_hash& peer)
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{
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char hex[sha1_hash::size() * 2];
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is.read(hex, sha1_hash::size() * 2);
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if (!aux::from_hex(hex, peer.data()))
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is.setstate(std::ios_base::failbit);
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return is;
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}
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#endif // TORRENT_USE_IOSTREAM
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namespace aux
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{
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void bits_shift_left(span<std::uint32_t> number, int n)
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{
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TORRENT_ASSERT(n >= 0);
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int const num_words = n / 32;
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int const number_size = int(number.size());
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if (num_words >= number_size)
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{
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std::memset(number.data(), 0, number_size * 4);
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return;
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}
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if (num_words > 0)
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{
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std::memmove(number.data(), number.data() + num_words
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, (number_size - num_words) * sizeof(std::uint32_t));
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std::memset(number.data() + (number_size - num_words)
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, 0, num_words * sizeof(std::uint32_t));
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n -= num_words * 32;
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}
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if (n > 0)
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{
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// keep in mind that the uint32_t are stored in network
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// byte order, so they have to be byteswapped before
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// applying the shift operations, and then byteswapped
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// back again.
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number[0] = aux::network_to_host(number[0]);
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for (int i = 0; i < number_size - 1; ++i)
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{
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number[i] <<= n;
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number[i + 1] = aux::network_to_host(number[i + 1]);
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number[i] |= number[i + 1] >> (32 - n);
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number[i] = aux::host_to_network(number[i]);
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}
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number[number_size - 1] <<= n;
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number[number_size - 1] = aux::host_to_network(number[number_size - 1]);
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}
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}
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void bits_shift_right(span<std::uint32_t> number, int n)
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{
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TORRENT_ASSERT(n >= 0);
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int const num_words = n / 32;
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int const number_size = int(number.size());
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if (num_words >= number_size)
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{
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std::memset(number.data(), 0, number_size * 4);
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return;
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}
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if (num_words > 0)
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{
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std::memmove(number.data() + num_words
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, number.data(), (number_size - num_words) * sizeof(std::uint32_t));
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std::memset(number.data(), 0, num_words * sizeof(std::uint32_t));
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n -= num_words * 32;
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}
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if (n > 0)
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{
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// keep in mind that the uint32_t are stored in network
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// byte order, so they have to be byteswapped before
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// applying the shift operations, and then byteswapped
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// back again.
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number[number_size - 1] = aux::network_to_host(number[number_size - 1]);
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for (int i = number_size - 1; i > 0; --i)
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{
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number[i] >>= n;
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number[i - 1] = aux::network_to_host(number[i - 1]);
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number[i] |= (number[i - 1] << (32 - n)) & 0xffffffff;
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number[i] = aux::host_to_network(number[i]);
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}
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number[0] >>= n;
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number[0] = aux::host_to_network(number[0]);
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}
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}
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}
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}
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