294 lines
7.6 KiB
C++
294 lines
7.6 KiB
C++
/*
|
|
|
|
Copyright (c) 2008, 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.
|
|
|
|
*/
|
|
|
|
#ifndef TORRENT_BITFIELD_HPP_INCLUDED
|
|
#define TORRENT_BITFIELD_HPP_INCLUDED
|
|
|
|
#include "libtorrent/assert.hpp"
|
|
#include "libtorrent/config.hpp"
|
|
#include <cstring> // for memset and memcpy
|
|
#include <cstdlib> // for malloc, free and realloc
|
|
#include <boost/cstdint.hpp> // uint32_t
|
|
|
|
namespace libtorrent
|
|
{
|
|
struct TORRENT_EXPORT bitfield
|
|
{
|
|
bitfield(): m_bytes(0), m_size(0), m_own(false) {}
|
|
bitfield(int bits): m_bytes(0), m_size(0), m_own(false)
|
|
{ resize(bits); }
|
|
bitfield(int bits, bool val): m_bytes(0), m_size(0), m_own(false)
|
|
{ resize(bits, val); }
|
|
bitfield(char const* b, int bits): m_bytes(0), m_size(0), m_own(false)
|
|
{ assign(b, bits); }
|
|
bitfield(bitfield const& rhs): m_bytes(0), m_size(0), m_own(false)
|
|
{ assign(rhs.bytes(), rhs.size()); }
|
|
|
|
void borrow_bytes(char* b, int bits)
|
|
{
|
|
dealloc();
|
|
m_bytes = (unsigned char*)b;
|
|
m_size = bits;
|
|
m_own = false;
|
|
}
|
|
~bitfield() { dealloc(); }
|
|
|
|
void assign(char const* b, int bits)
|
|
{ resize(bits); std::memcpy(m_bytes, b, (bits + 7) / 8); clear_trailing_bits(); }
|
|
|
|
bool operator[](int index) const
|
|
{ return get_bit(index); }
|
|
|
|
bool get_bit(int index) const
|
|
{
|
|
TORRENT_ASSERT(index >= 0);
|
|
TORRENT_ASSERT(index < m_size);
|
|
return (m_bytes[index / 8] & (0x80 >> (index & 7))) != 0;
|
|
}
|
|
|
|
void clear_bit(int index)
|
|
{
|
|
TORRENT_ASSERT(index >= 0);
|
|
TORRENT_ASSERT(index < m_size);
|
|
m_bytes[index / 8] &= ~(0x80 >> (index & 7));
|
|
}
|
|
|
|
// returns true if all bits in the bitfield are set
|
|
bool all_set() const
|
|
{
|
|
const int num_words = m_size / 32;
|
|
const int num_bytes = m_size / 8;
|
|
boost::uint32_t* bits = (boost::uint32_t*)m_bytes;
|
|
for (int i = 0; i < num_words; ++i)
|
|
{
|
|
if (bits[i] != 0xffffffff) return false;
|
|
}
|
|
|
|
for (int i = num_words * 4; i < num_bytes; ++i)
|
|
{
|
|
if (m_bytes[i] != 0xff) return false;
|
|
}
|
|
int rest = m_size - num_bytes * 8;
|
|
boost::uint8_t mask = 0xff << (8-rest);
|
|
if (rest > 0 && (m_bytes[num_bytes] & mask) != mask)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
void set_bit(int index)
|
|
{
|
|
TORRENT_ASSERT(index >= 0);
|
|
TORRENT_ASSERT(index < m_size);
|
|
m_bytes[index / 8] |= (0x80 >> (index & 7));
|
|
}
|
|
|
|
std::size_t size() const { return m_size; }
|
|
bool empty() const { return m_size == 0; }
|
|
|
|
char const* bytes() const { return (char*)m_bytes; }
|
|
|
|
bitfield& operator=(bitfield const& rhs)
|
|
{
|
|
assign(rhs.bytes(), rhs.size());
|
|
return *this;
|
|
}
|
|
|
|
int count() const
|
|
{
|
|
// 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111,
|
|
// 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111
|
|
const static char num_bits[] =
|
|
{
|
|
0, 1, 1, 2, 1, 2, 2, 3,
|
|
1, 2, 2, 3, 2, 3, 3, 4
|
|
};
|
|
|
|
int ret = 0;
|
|
const int num_bytes = m_size / 8;
|
|
for (int i = 0; i < num_bytes; ++i)
|
|
{
|
|
ret += num_bits[m_bytes[i] & 0xf] + num_bits[m_bytes[i] >> 4];
|
|
}
|
|
|
|
int rest = m_size - num_bytes * 8;
|
|
for (int i = 0; i < rest; ++i)
|
|
{
|
|
ret += (m_bytes[num_bytes] >> (7-i)) & 1;
|
|
}
|
|
TORRENT_ASSERT(ret <= m_size);
|
|
TORRENT_ASSERT(ret >= 0);
|
|
return ret;
|
|
}
|
|
|
|
struct const_iterator
|
|
{
|
|
friend struct bitfield;
|
|
|
|
typedef bool value_type;
|
|
typedef ptrdiff_t difference_type;
|
|
typedef bool const* pointer;
|
|
typedef bool& reference;
|
|
typedef std::forward_iterator_tag iterator_category;
|
|
|
|
bool operator*() { return (*byte & bit) != 0; }
|
|
const_iterator& operator++() { inc(); return *this; }
|
|
const_iterator operator++(int)
|
|
{ const_iterator ret(*this); inc(); return ret; }
|
|
const_iterator& operator--() { dec(); return *this; }
|
|
const_iterator operator--(int)
|
|
{ const_iterator ret(*this); dec(); return ret; }
|
|
|
|
const_iterator(): byte(0), bit(0x80) {}
|
|
bool operator==(const_iterator const& rhs) const
|
|
{ return byte == rhs.byte && bit == rhs.bit; }
|
|
|
|
bool operator!=(const_iterator const& rhs) const
|
|
{ return byte != rhs.byte || bit != rhs.bit; }
|
|
|
|
private:
|
|
void inc()
|
|
{
|
|
TORRENT_ASSERT(byte);
|
|
if (bit == 0x01)
|
|
{
|
|
bit = 0x80;
|
|
++byte;
|
|
}
|
|
else
|
|
{
|
|
bit >>= 1;
|
|
}
|
|
}
|
|
void dec()
|
|
{
|
|
TORRENT_ASSERT(byte);
|
|
if (bit == 0x80)
|
|
{
|
|
bit = 0x01;
|
|
--byte;
|
|
}
|
|
else
|
|
{
|
|
bit <<= 1;
|
|
}
|
|
}
|
|
const_iterator(unsigned char const* ptr, int offset)
|
|
: byte(ptr), bit(0x80 >> offset) {}
|
|
unsigned char const* byte;
|
|
int bit;
|
|
};
|
|
|
|
const_iterator begin() const { return const_iterator(m_bytes, 0); }
|
|
const_iterator end() const { return const_iterator(m_bytes + m_size / 8, m_size & 7); }
|
|
|
|
void resize(int bits, bool val)
|
|
{
|
|
int s = m_size;
|
|
int b = m_size & 7;
|
|
resize(bits);
|
|
if (s >= m_size) return;
|
|
int old_size_bytes = (s + 7) / 8;
|
|
int new_size_bytes = (m_size + 7) / 8;
|
|
if (val)
|
|
{
|
|
if (old_size_bytes && b) m_bytes[old_size_bytes - 1] |= (0xff >> b);
|
|
if (old_size_bytes < new_size_bytes)
|
|
std::memset(m_bytes + old_size_bytes, 0xff, new_size_bytes - old_size_bytes);
|
|
clear_trailing_bits();
|
|
}
|
|
else
|
|
{
|
|
if (old_size_bytes < new_size_bytes)
|
|
std::memset(m_bytes + old_size_bytes, 0x00, new_size_bytes - old_size_bytes);
|
|
}
|
|
}
|
|
|
|
void set_all()
|
|
{
|
|
std::memset(m_bytes, 0xff, (m_size + 7) / 8);
|
|
clear_trailing_bits();
|
|
}
|
|
|
|
void clear_all()
|
|
{
|
|
std::memset(m_bytes, 0x00, (m_size + 7) / 8);
|
|
}
|
|
|
|
void resize(int bits)
|
|
{
|
|
TORRENT_ASSERT(bits >= 0);
|
|
const int b = (bits + 7) / 8;
|
|
if (m_bytes)
|
|
{
|
|
if (m_own)
|
|
{
|
|
m_bytes = (unsigned char*)std::realloc(m_bytes, b);
|
|
m_own = true;
|
|
}
|
|
else if (bits > m_size)
|
|
{
|
|
unsigned char* tmp = (unsigned char*)std::malloc(b);
|
|
std::memcpy(tmp, m_bytes, (std::min)(int(m_size + 7)/ 8, b));
|
|
m_bytes = tmp;
|
|
m_own = true;
|
|
}
|
|
}
|
|
else if (bits > 0)
|
|
{
|
|
m_bytes = (unsigned char*)std::malloc(b);
|
|
m_own = true;
|
|
}
|
|
m_size = bits;
|
|
clear_trailing_bits();
|
|
}
|
|
|
|
void free() { dealloc(); m_size = 0; }
|
|
|
|
private:
|
|
|
|
void clear_trailing_bits()
|
|
{
|
|
// clear the tail bits in the last byte
|
|
if (m_size & 7) m_bytes[(m_size + 7) / 8 - 1] &= 0xff << (8 - (m_size & 7));
|
|
}
|
|
|
|
void dealloc() { if (m_own) std::free(m_bytes); m_bytes = 0; }
|
|
unsigned char* m_bytes;
|
|
int m_size:31; // in bits
|
|
bool m_own:1;
|
|
};
|
|
|
|
}
|
|
|
|
#endif // TORRENT_BITFIELD_HPP_INCLUDED
|
|
|