premiere-libtorrent/src/bitfield.cpp

164 lines
4.4 KiB
C++

/*
Copyright (c) 2008-2016, Arvid Norberg
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the distribution.
* Neither the name of the author nor the names of its
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
#include "libtorrent/bitfield.hpp"
#include "libtorrent/aux_/cpuid.hpp"
#ifdef _MSC_VER
#include <intrin.h>
#endif
namespace libtorrent
{
bool bitfield::all_set() const
{
const int words = size() / 32;
for (int i = 0; i < words; ++i)
{
if (m_buf[i] != 0xffffffff) return false;
}
int rest = size() & 31;
if (rest > 0)
{
boost::uint32_t mask = aux::host_to_network(0xffffffff << (32-rest));
if ((m_buf[words] & mask) != mask) return false;
}
return true;
}
int bitfield::count() const
{
int ret = 0;
const int words = num_words();
#if TORRENT_HAS_SSE
if (aux::mmx_support)
{
for (int i = 0; i < words; ++i)
{
#ifdef __GNUC__
boost::uint32_t cnt = 0;
__asm__("popcnt %1, %0"
: "=r"(cnt)
: "r"(m_buf[i]));
ret += cnt;
#else
ret += _mm_popcnt_u32(m_buf[i]);
#endif
}
return ret;
}
#endif // TORRENT_HAS_SSE
for (int i = 0; i < words; ++i)
{
boost::uint32_t v = m_buf[i];
// from:
// http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
static const int S[] = {1, 2, 4, 8, 16}; // Magic Binary Numbers
static const int B[] = {0x55555555, 0x33333333, 0x0F0F0F0F, 0x00FF00FF, 0x0000FFFF};
boost::uint32_t c = v - ((v >> 1) & B[0]);
c = ((c >> S[1]) & B[1]) + (c & B[1]);
c = ((c >> S[2]) + c) & B[2];
c = ((c >> S[3]) + c) & B[3];
c = ((c >> S[4]) + c) & B[4];
ret += c;
}
TORRENT_ASSERT(ret <= size());
TORRENT_ASSERT(ret >= 0);
return ret;
}
void bitfield::resize(int bits, bool val)
{
if (bits == size()) return;
int s = size();
int b = size() & 31;
resize(bits);
if (s >= size()) return;
int old_size_words = (s + 31) / 32;
int new_size_words = num_words();
if (val)
{
if (old_size_words && b) m_buf[old_size_words - 1] |= aux::host_to_network((0xffffffff >> b));
if (old_size_words < new_size_words)
std::memset(m_buf + old_size_words, 0xff
, size_t((new_size_words - old_size_words) * 4));
clear_trailing_bits();
}
else
{
if (old_size_words < new_size_words)
std::memset(m_buf + old_size_words, 0x00
, size_t((new_size_words - old_size_words) * 4));
}
TORRENT_ASSERT(size() == bits);
}
void bitfield::resize(int bits)
{
if (bits == size()) return;
TORRENT_ASSERT(bits >= 0);
// +1 because the first word is the size (in bits)
const int b = (bits + 31) / 32;
if (m_buf)
{
boost::uint32_t* tmp = static_cast<boost::uint32_t*>(std::realloc(m_buf-1, (b+1) * 4));
#ifndef BOOST_NO_EXCEPTIONS
if (tmp == NULL) throw std::bad_alloc();
#endif
m_buf = tmp + 1;
m_buf[-1] = bits;
}
else if (bits > 0)
{
boost::uint32_t* tmp = static_cast<boost::uint32_t*>(std::malloc((b+1) * 4));
#ifndef BOOST_NO_EXCEPTIONS
if (tmp == NULL) throw std::bad_alloc();
#endif
m_buf = tmp + 1;
m_buf[-1] = bits;
}
else if (m_buf != NULL)
{
std::free(m_buf-1);
m_buf = NULL;
}
clear_trailing_bits();
TORRENT_ASSERT(size() == bits);
}
}