231 lines
6.7 KiB
C++
231 lines
6.7 KiB
C++
/*
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Copyright (c) 2008-2018, 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/bitfield.hpp"
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#include "libtorrent/aux_/numeric_cast.hpp"
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#include "libtorrent/aux_/cpuid.hpp"
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#ifdef _MSC_VER
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#include <intrin.h>
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#endif
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namespace libtorrent {
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bool bitfield::all_set() const noexcept
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{
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if(size() == 0) return false;
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int const words = size() / 32;
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for (int i = 1; i < words + 1; ++i)
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{
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if (m_buf[i] != 0xffffffff) return false;
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}
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int const rest = size() & 31;
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if (rest > 0)
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{
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std::uint32_t const mask = aux::host_to_network(0xffffffff << (32 - rest));
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if ((m_buf[words + 1] & mask) != mask) return false;
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}
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return true;
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}
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int bitfield::count() const noexcept
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{
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int ret = 0;
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int const words = num_words();
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#if TORRENT_HAS_SSE
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if (aux::mmx_support)
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{
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for (int i = 1; i < words + 1; ++i)
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{
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#ifdef __GNUC__
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std::uint32_t cnt = 0;
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__asm__("popcnt %1, %0"
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: "=r"(cnt)
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: "r"(m_buf[i]));
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ret += cnt;
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#else
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ret += _mm_popcnt_u32(m_buf[i]);
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#endif
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}
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TORRENT_ASSERT(ret <= size());
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TORRENT_ASSERT(ret >= 0);
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return ret;
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}
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#endif // TORRENT_HAS_SSE
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#if TORRENT_HAS_ARM_NEON && defined __arm__
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if (aux::arm_neon_support)
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{
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for (int i = 1; i < words + 1; ++i)
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{
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std::uint32_t cnt;
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__asm__(
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"vld1.u32 d0[0], [%1] \n"
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"vcnt.u8 d0, d0 \n"
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"vpaddl.u8 d0, d0 \n"
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"vpaddl.u16 d0, d0 \n"
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"vst1.u32 d0[0], [%0]"
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:: "r"(&cnt), "r"(&m_buf[i])
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: "d0", "memory");
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ret += cnt;
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}
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TORRENT_ASSERT(ret <= size());
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TORRENT_ASSERT(ret >= 0);
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return ret;
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}
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#endif // TORRENT_HAS_ARM_NEON
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for (int i = 1; i < words + 1; ++i)
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{
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std::uint32_t const v = m_buf[i];
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// from:
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// http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
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static const int S[] = {1, 2, 4, 8, 16}; // Magic Binary Numbers
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static const std::uint32_t B[] = {0x55555555, 0x33333333, 0x0F0F0F0F, 0x00FF00FF, 0x0000FFFF};
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std::uint32_t c = v - ((v >> 1) & B[0]);
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c = ((c >> S[1]) & B[1]) + (c & B[1]);
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c = ((c >> S[2]) + c) & B[2];
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c = ((c >> S[3]) + c) & B[3];
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c = ((c >> S[4]) + c) & B[4];
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ret += c;
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TORRENT_ASSERT(ret <= size());
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}
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TORRENT_ASSERT(ret <= size());
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TORRENT_ASSERT(ret >= 0);
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return ret;
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}
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void bitfield::resize(int const bits, bool const val)
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{
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if (bits == size()) return;
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int const s = size();
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int const b = size() & 31;
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resize(bits);
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if (s >= size()) return;
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int const old_size_words = (s + 31) / 32;
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int const new_size_words = num_words();
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if (val)
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{
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if (old_size_words && b) buf()[old_size_words - 1] |= aux::host_to_network(0xffffffff >> b);
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if (old_size_words < new_size_words)
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std::memset(buf() + old_size_words, 0xff
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, static_cast<std::size_t>(new_size_words - old_size_words) * 4);
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clear_trailing_bits();
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}
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else
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{
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if (old_size_words < new_size_words)
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std::memset(buf() + old_size_words, 0x00
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, static_cast<std::size_t>(new_size_words - old_size_words) * 4);
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}
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TORRENT_ASSERT(size() == bits);
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}
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void bitfield::resize(int const bits)
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{
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if (bits == size()) return;
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TORRENT_ASSERT(bits >= 0);
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if (bits == 0)
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{
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m_buf.reset();
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return;
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}
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int const new_size_words = (bits + 31) / 32;
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int const cur_size_words = num_words();
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if (cur_size_words != new_size_words)
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{
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aux::unique_ptr<std::uint32_t[]> b(new std::uint32_t[std::size_t(new_size_words + 1)]);
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#ifdef BOOST_NO_EXCEPTIONS
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if (b == nullptr) std::terminate();
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#endif
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b[0] = aux::numeric_cast<std::uint32_t>(bits);
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if (m_buf) std::memcpy(&b[1], buf()
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, aux::numeric_cast<std::size_t>(std::min(new_size_words, cur_size_words) * 4));
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if (new_size_words > cur_size_words)
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{
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std::memset(&b[1 + cur_size_words], 0
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, aux::numeric_cast<std::size_t>((new_size_words - cur_size_words) * 4));
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}
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m_buf = std::move(b);
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}
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else
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{
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m_buf[0] = aux::numeric_cast<std::uint32_t>(bits);
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}
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clear_trailing_bits();
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TORRENT_ASSERT(size() == bits);
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}
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int bitfield::find_first_set() const noexcept
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{
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int const num = num_words();
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if (num == 0) return -1;
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int const count = aux::count_leading_zeros({&m_buf[1], num});
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return count != num * 32 ? count : -1;
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}
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int bitfield::find_last_clear() const noexcept
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{
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int const num = num_words();
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if (num == 0) return - 1;
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int const size = this->size();
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std::uint32_t const mask = 0xffffffff << (32 - (size & 31));
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std::uint32_t const last = m_buf[num] ^ aux::host_to_network(mask);
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int const ext = aux::count_trailing_ones(~last) - (31 - (size % 32));
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return last != 0
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? (num - 1) * 32 + ext
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: size - (aux::count_trailing_ones({&m_buf[1], num - 1}) + ext);
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}
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static_assert(std::is_nothrow_move_constructible<bitfield>::value
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, "should be nothrow move constructible");
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static_assert(std::is_nothrow_move_assignable<bitfield>::value
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, "should be nothrow move assignable");
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static_assert(std::is_nothrow_default_constructible<bitfield>::value
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, "should be nothrow default constructible");
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static_assert(std::is_nothrow_move_constructible<typed_bitfield<int>>::value
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, "should be nothrow move constructible");
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static_assert(std::is_nothrow_move_assignable<typed_bitfield<int>>::value
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, "should be nothrow move assignable");
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static_assert(std::is_nothrow_default_constructible<typed_bitfield<int>>::value
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, "should be nothrow default constructible");
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}
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