zeek/src/probabilistic/BitVector.cc
2025-07-28 13:03:25 -07:00

486 lines
12 KiB
C++

// See the file "COPYING" in the main distribution directory for copyright.
#include "zeek/probabilistic/BitVector.h"
#include <openssl/sha.h>
#include <cassert>
#include <cstring>
#include <limits>
#include "zeek/broker/Data.h"
#include "zeek/digest.h"
namespace zeek::probabilistic::detail {
BitVector::size_type BitVector::npos = static_cast<BitVector::size_type>(-1);
BitVector::block_type BitVector::bits_per_block = std::numeric_limits<BitVector::block_type>::digits;
namespace {
constexpr uint8_t count_table[] = {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3,
3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4,
3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4,
4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5,
3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 1, 2,
2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,
4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5,
5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5,
5, 6, 5, 6, 6, 7, 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8};
} // namespace
BitVector::Reference::Reference(block_type& block, block_type i) : block(block), mask((block_type(1) << i)) {
assert(i < bits_per_block);
}
BitVector::Reference& BitVector::Reference::Flip() {
block ^= mask;
return *this;
}
BitVector::Reference::operator bool() const { return (block & mask) != 0; }
bool BitVector::Reference::operator~() const { return (block & mask) == 0; }
BitVector::Reference& BitVector::Reference::operator=(bool x) {
if ( x )
block |= mask;
else
block &= ~mask;
return *this;
}
BitVector::Reference& BitVector::Reference::operator=(const Reference& other) {
if ( other )
block |= mask;
else
block &= ~mask;
return *this;
}
BitVector::Reference& BitVector::Reference::operator|=(bool x) {
if ( x )
block |= mask;
return *this;
}
BitVector::Reference& BitVector::Reference::operator&=(bool x) {
if ( ! x )
block &= ~mask;
return *this;
}
BitVector::Reference& BitVector::Reference::operator^=(bool x) {
if ( x )
block ^= mask;
return *this;
}
BitVector::Reference& BitVector::Reference::operator-=(bool x) {
if ( x )
block &= ~mask;
return *this;
}
BitVector::BitVector() { num_bits = 0; }
BitVector::BitVector(size_type size, bool value) : bits(bits_to_blocks(size), value ? ~block_type(0) : 0) {
num_bits = size;
}
BitVector::BitVector(BitVector const& other) : bits(other.bits) { num_bits = other.num_bits; }
BitVector BitVector::operator~() const {
BitVector b(*this);
b.Flip();
return b;
}
BitVector& BitVector::operator=(BitVector const& other) {
bits = other.bits;
return *this;
}
BitVector BitVector::operator<<(size_type n) const {
BitVector b(*this);
return b <<= n;
}
BitVector BitVector::operator>>(size_type n) const {
BitVector b(*this);
return b >>= n;
}
BitVector& BitVector::operator<<=(size_type n) {
if ( n >= num_bits )
return Reset();
if ( n > 0 ) {
size_type last = Blocks() - 1;
size_type div = n / bits_per_block;
block_type r = bit_index(n);
block_type* b = &bits[0];
assert(Blocks() >= 1);
assert(div <= last);
if ( r != 0 ) {
for ( size_type i = last - div; i > 0; --i )
b[i + div] = (b[i] << r) | (b[i - 1] >> (bits_per_block - r));
b[div] = b[0] << r;
}
else {
for ( size_type i = last - div; i > 0; --i )
b[i + div] = b[i];
b[div] = b[0];
}
std::fill_n(b, div, block_type(0));
zero_unused_bits();
}
return *this;
}
BitVector& BitVector::operator>>=(size_type n) {
if ( n >= num_bits )
return Reset();
if ( n > 0 ) {
size_type last = Blocks() - 1;
size_type div = n / bits_per_block;
block_type r = bit_index(n);
block_type* b = &bits[0];
assert(Blocks() >= 1);
assert(div <= last);
if ( r != 0 ) {
for ( size_type i = last - div; i > 0; --i )
b[i - div] = (b[i] >> r) | (b[i + 1] << (bits_per_block - r));
b[last - div] = b[last] >> r;
}
else {
for ( size_type i = div; i <= last; ++i )
b[i - div] = b[i];
}
std::fill_n(b + (Blocks() - div), div, block_type(0));
}
return *this;
}
BitVector& BitVector::operator&=(BitVector const& other) {
assert(Size() >= other.Size());
for ( size_type i = 0; i < Blocks(); ++i )
bits[i] &= other.bits[i];
return *this;
}
BitVector& BitVector::operator|=(BitVector const& other) {
assert(Size() >= other.Size());
for ( size_type i = 0; i < Blocks(); ++i )
bits[i] |= other.bits[i];
return *this;
}
BitVector& BitVector::operator^=(BitVector const& other) {
assert(Size() >= other.Size());
for ( size_type i = 0; i < Blocks(); ++i )
bits[i] ^= other.bits[i];
return *this;
}
BitVector& BitVector::operator-=(BitVector const& other) {
assert(Size() >= other.Size());
for ( size_type i = 0; i < Blocks(); ++i )
bits[i] &= ~other.bits[i];
return *this;
}
BitVector operator&(BitVector const& x, BitVector const& y) {
BitVector b(x);
return b &= y;
}
BitVector operator|(BitVector const& x, BitVector const& y) {
BitVector b(x);
return b |= y;
}
BitVector operator^(BitVector const& x, BitVector const& y) {
BitVector b(x);
return b ^= y;
}
BitVector operator-(BitVector const& x, BitVector const& y) {
BitVector b(x);
return b -= y;
}
bool operator==(BitVector const& x, BitVector const& y) { return x.num_bits == y.num_bits && x.bits == y.bits; }
bool operator!=(BitVector const& x, BitVector const& y) { return ! (x == y); }
bool operator<(BitVector const& x, BitVector const& y) {
assert(x.Size() == y.Size());
for ( BitVector::size_type r = x.Blocks(); r > 0; --r ) {
BitVector::size_type i = r - 1;
if ( x.bits[i] < y.bits[i] )
return true;
else if ( x.bits[i] > y.bits[i] )
return false;
}
return false;
}
void BitVector::Resize(size_type n, bool value) {
size_type old = Blocks();
size_type required = bits_to_blocks(n);
block_type block_value = value ? ~block_type(0) : block_type(0);
if ( required != old )
bits.resize(required, block_value);
if ( value && (n > num_bits) && extra_bits() )
bits[old - 1] |= (block_value << extra_bits());
num_bits = n;
zero_unused_bits();
}
void BitVector::Clear() {
bits.clear();
num_bits = 0;
}
void BitVector::PushBack(bool bit) {
size_type s = Size();
Resize(s + 1);
Set(s, bit);
}
void BitVector::Append(block_type block) {
size_type excess = extra_bits();
if ( excess ) {
assert(! Empty());
bits.push_back(block >> (bits_per_block - excess));
bits[Blocks() - 2] |= (block << excess);
}
else {
bits.push_back(block);
}
num_bits += bits_per_block;
}
BitVector& BitVector::Set(size_type i, bool bit) {
assert(i < num_bits);
if ( bit )
bits[block_index(i)] |= bit_mask(i);
else
Reset(i);
return *this;
}
BitVector& BitVector::Set() {
std::ranges::fill(bits, ~block_type(0));
zero_unused_bits();
return *this;
}
BitVector& BitVector::Reset(size_type i) {
assert(i < num_bits);
bits[block_index(i)] &= ~bit_mask(i);
return *this;
}
BitVector& BitVector::Reset() {
std::ranges::fill(bits, block_type(0));
return *this;
}
BitVector& BitVector::Flip(size_type i) {
assert(i < num_bits);
bits[block_index(i)] ^= bit_mask(i);
return *this;
}
BitVector& BitVector::Flip() {
for ( size_type i = 0; i < Blocks(); ++i )
bits[i] = ~bits[i];
zero_unused_bits();
return *this;
}
bool BitVector::operator[](size_type i) const {
assert(i < num_bits);
return (bits[block_index(i)] & bit_mask(i)) != 0;
}
BitVector::Reference BitVector::operator[](size_type i) {
assert(i < num_bits);
return {bits[block_index(i)], bit_index(i)};
}
BitVector::size_type BitVector::Count() const {
std::vector<block_type>::const_iterator first = bits.begin();
size_t n = 0;
size_type length = Blocks();
while ( length ) {
block_type block = *first;
while ( block ) {
// TODO: use _popcnt if available.
n += count_table[block & ((1u << 8) - 1)];
block >>= 8;
}
++first;
--length;
}
return n;
}
BitVector::size_type BitVector::Blocks() const { return bits.size(); }
BitVector::size_type BitVector::Size() const { return num_bits; }
bool BitVector::Empty() const { return bits.empty(); }
bool BitVector::AllZero() const {
for ( unsigned long long bit : bits ) {
if ( bit )
return false;
}
return true;
}
BitVector::size_type BitVector::FindFirst() const { return find_from(0); }
BitVector::size_type BitVector::FindNext(size_type i) const {
if ( i >= (Size() - 1) || Size() == 0 )
return npos;
++i;
size_type bi = block_index(i);
block_type block = bits[bi] & (~block_type(0) << bit_index(i));
return block ? bi * bits_per_block + lowest_bit(block) : find_from(bi + 1);
}
uint64_t BitVector::Hash() const {
u_char buf[SHA256_DIGEST_LENGTH];
uint64_t digest;
auto* ctx = zeek::detail::hash_init(zeek::detail::Hash_SHA256);
for ( size_type i = 0; i < Blocks(); ++i )
zeek::detail::hash_update(ctx, &bits[i], sizeof(bits[i]));
zeek::detail::hash_final(ctx, buf);
memcpy(&digest, buf, sizeof(digest)); // Use the first bytes as digest
return digest;
}
std::optional<BrokerData> BitVector::Serialize() const {
BrokerListBuilder builder;
builder.Reserve(2 + bits.size());
builder.AddCount(num_bits);
builder.AddCount(bits.size());
for ( auto bit : bits )
builder.AddCount(bit);
return std::move(builder).Build();
}
std::unique_ptr<BitVector> BitVector::Unserialize(BrokerDataView data) {
if ( ! data.IsList() )
return nullptr;
auto v = data.ToList();
if ( v.Size() < 2 || ! v[0].IsCount() || ! v[1].IsCount() )
return nullptr;
auto num_bits = v[0].ToCount();
auto size = v[1].ToCount();
if ( v.Size() != 2 + size )
return nullptr;
auto bv = std::make_unique<BitVector>();
bv->num_bits = num_bits;
for ( size_t i = 0; i < size; ++i ) {
auto x = v[2 + i];
if ( ! x.IsCount() )
return nullptr;
bv->bits.push_back(x.ToCount());
}
return bv;
}
BitVector::size_type BitVector::lowest_bit(block_type block) {
block_type x = block - (block & (block - 1));
size_type log = 0;
while ( x >>= 1 )
++log;
return log;
}
BitVector::block_type BitVector::extra_bits() const { return bit_index(Size()); }
void BitVector::zero_unused_bits() {
if ( extra_bits() )
bits.back() &= ~(~block_type(0) << extra_bits());
}
BitVector::size_type BitVector::find_from(size_type i) const {
while ( i < Blocks() && bits[i] == 0 )
++i;
if ( i >= Blocks() )
return npos;
return i * bits_per_block + lowest_bit(bits[i]);
}
} // namespace zeek::probabilistic::detail