A vector of bits. More...

#include "bitSet.h"

Inheritance diagram for epics::pvData::BitSet:

Collaboration diagram for epics::pvData::BitSet:

Public Member Functions
	POINTER_DEFINITIONS (BitSet)

	BitSet ()

	BitSet (uint32 nbits)

virtual	~BitSet ()

BitSet &	flip (uint32 bitIndex)

BitSet &	set (uint32 bitIndex)

BitSet &	clear (uint32 bitIndex)

void	set (uint32 bitIndex, bool value)

bool	get (uint32 bitIndex) const

void	clear ()

int32	nextSetBit (uint32 fromIndex) const

int32	nextClearBit (uint32 fromIndex) const

bool	isEmpty () const

uint32	cardinality () const

uint32	size () const

bool	logical_and (const BitSet &other) const
	Returns true if any bit is set in both *this and other. More...

bool	logical_or (const BitSet &other) const
	Returns true if any bit is set in both *this or other. More...

BitSet &	operator&= (const BitSet &set)

BitSet &	operator\|= (const BitSet &set)

BitSet &	operator^= (const BitSet &set)

BitSet &	operator= (const BitSet &set)

void	swap (BitSet &set)
	Swap contents. More...

void	or_and (const BitSet &set1, const BitSet &set2)

bool	operator== (const BitSet &set) const

bool	operator!= (const BitSet &set) const

virtual void	serialize (ByteBuffer buffer, SerializableControl flusher) const

virtual void	deserialize (ByteBuffer buffer, DeserializableControl flusher)

Public Member Functions inherited from epics::pvData::Serializable
virtual	~Serializable ()

Static Public Member Functions
static BitSetPtr	create (uint32 nbits)

Detailed Description

A vector of bits.

This class implements a vector of bits that grows as needed. Each component of the bit set has a bool value. The bits of a BitSet are indexed by nonnegative integers. Individual indexed bits can be examined, set, or cleared. One BitSet may be used to modify the contents of another BitSet through logical AND, logical inclusive OR, and logical exclusive OR operations.

By default, all bits in the set initially have the value false.

Every bit set has a current size, which is the number of bits of space currently in use by the bit set. Note that the size is related to the implementation of a bit set, so it may change with implementation. The length of a bit set relates to logical length of a bit set and is defined independently of implementation.

A BitSet is not safe for multithreaded use without external synchronization.

Based on Java implementation.

Since: 7.0.0 Many methods return BitSet& to facilite method chaining.

Definition at line 56 of file bitSet.h.

Constructor & Destructor Documentation

epics::pvData::BitSet::BitSet ( )

Creates a new bit set. All bits are initially false.

Definition at line 51 of file bitSet.cpp.

51 {}

epics::pvData::BitSet::BitSet ( uint32 nbits )

Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range 0 through nbits-1. All bits are initially false.

Parameters

nbits the initial size of the bit set

Definition at line 53 of file bitSet.cpp.

     {
         words.reserve((nbits == 0) ? 1 : WORD_INDEX(nbits-1) + 1);
     }

epics::pvData::BitSet::~BitSet ( )

virtual

Destructor.

Definition at line 71 of file bitSet.cpp.

71 {}

Member Function Documentation

uint32 epics::pvData::BitSet::cardinality ( ) const

Returns the number of bits set to true in this BitSet.

Returns: the number of bits set to true in this BitSet

Definition at line 203 of file bitSet.cpp.

                                      {
         uint32 sum = 0;
         for (uint32 i = 0; i < words.size(); i++)
             sum += bitCount(words[i]);
         return sum;
     }

BitSet & epics::pvData::BitSet::clear ( uint32 bitIndex )

Sets the bit specified by the index to false.

Parameters

bitIndex the index of the bit to be cleared

Definition at line 112 of file bitSet.cpp.

                                          {
 
         uint32 wordIdx = WORD_INDEX(bitIndex);
         if (wordIdx < words.size()) {
             words[wordIdx] &= ~(((uint64)1) << WORD_OFFSET(bitIndex));
 
             recalculateWordsInUse();
         }
         return *this;
     }

void epics::pvData::BitSet::clear ( )

Sets all of the bits in this BitSet to false.

Definition at line 136 of file bitSet.cpp.

                        {
         words.clear();
     }

BitSet::shared_pointer epics::pvData::BitSet::create ( uint32 nbits )

static

Definition at line 46 of file bitSet.cpp.

     {
         return BitSet::shared_pointer(new BitSet(nbits));
     }

void epics::pvData::BitSet::deserialize	(	ByteBuffer *	buffer,
		DeserializableControl *	flusher
	)

virtual

Deserialize buffer.

Parameters

buffer	serialization buffer.
flusher	deserialization control.

Implements epics::pvData::Serializable.

Definition at line 339 of file bitSet.cpp.

                                                                                {
 
         uint32 bytes = static_cast<uint32>(SerializeHelper::readSize(buffer, control)); // in bytes
 
         size_t wordsInUse = (bytes + 7) / BYTES_PER_WORD;
         words.resize(wordsInUse);
 
         if (wordsInUse == 0)
             return;
 
         control->ensureData(bytes);
 
         uint32 i = 0;
         uint32 longs = bytes / 8;
         while (i < longs)
             words[i++] = buffer->getLong();
 
         for (uint32 j = i; j < wordsInUse; j++)
             words[j] = 0;
 
         for (uint32 remaining = (bytes - longs * 8), j = 0; j < remaining; j++)
             words[i] |= (buffer->getByte() & 0xffLL) << (8 * j);
 
         recalculateWordsInUse(); // Sender shouldn't add extra zero bytes, but don't fail it it does
     }

BitSet & epics::pvData::BitSet::flip ( uint32 bitIndex )

Sets the bit at the specified index to the complement of its current value.

Parameters

bitIndex the index of the bit to flip

Definition at line 92 of file bitSet.cpp.

                                         {
 
         uint32 wordIdx = WORD_INDEX(bitIndex);
         expandTo(wordIdx);
 
         words[wordIdx] ^= (((uint64)1) << WORD_OFFSET(bitIndex));
 
         recalculateWordsInUse();
         return *this;
     }

bool epics::pvData::BitSet::get ( uint32 bitIndex ) const

Returns the value of the bit with the specified index. The value is true if the bit with the index bitIndex is currently set in this BitSet; otherwise, the result is false.

Parameters

bitIndex the bit index

Returns: the value of the bit with the specified index

Definition at line 130 of file bitSet.cpp.

                                           {
         uint32 wordIdx = WORD_INDEX(bitIndex);
         return ((wordIdx < words.size())
             && ((words[wordIdx] & (((uint64)1) << WORD_OFFSET(bitIndex))) != 0));
     }

bool epics::pvData::BitSet::isEmpty ( ) const

Returns true if this BitSet contains no bits that are set to true.

Returns: indicating whether this BitSet is empty

Definition at line 199 of file bitSet.cpp.

                                {
         return words.empty();
     }

bool epics::pvData::BitSet::logical_and ( const BitSet & other ) const

Returns true if any bit is set in both *this and other.

Definition at line 214 of file bitSet.cpp.

     {
         size_t nwords = std::min(words.size(), set.words.size());
         for(size_t i=0; i<nwords; i++) {
             if(words[i] & set.words[i])
                 return true;
         }
         return false;
     }

bool epics::pvData::BitSet::logical_or ( const BitSet & other ) const

Returns true if any bit is set in both *this or other.

Definition at line 223 of file bitSet.cpp.

     {
         return !words.empty() || !set.words.empty();
     }

int32 epics::pvData::BitSet::nextClearBit ( uint32 fromIndex ) const

Returns the index of the first bit that is set to false that occurs on or after the specified starting index.

Parameters

fromIndex the index to start checking from (inclusive)

Returns: the index of the next clear bit

Definition at line 181 of file bitSet.cpp.

                                                      {
         // Neither spec nor implementation handle bitsets of maximal length.
 
         uint32 u = WORD_INDEX(fromIndex);
         if (u >= words.size())
             return fromIndex;
 
         uint64 word = ~words[u] & (WORD_MASK << (fromIndex % BITS_PER_WORD));
 
         while (true) {
             if (word != 0)
                 return (u * BITS_PER_WORD) + numberOfTrailingZeros(word);
             if (++u == words.size())
                 return words.size() * BITS_PER_WORD;
             word = ~words[u];
         }
     }

int32 epics::pvData::BitSet::nextSetBit ( uint32 fromIndex ) const

Returns the index of the first bit that is set to true that occurs on or after the specified starting index. If no such bit exists then -1 is returned.

To iterate over the true bits in a BitSet, use the following loop:

for (int32 i = bs.nextSetBit(0); i >= 0; i = bs.nextSetBit(i+1)) {
    // operate on index i here
}

Parameters

fromIndex the index to start checking from (inclusive)

Returns: the index of the next set bit, or -1 if there is no such bit

Definition at line 164 of file bitSet.cpp.

                                                    {
 
         uint32 u = WORD_INDEX(fromIndex);
         if (u >= words.size())
             return -1;
 
         uint64 word = words[u] & (WORD_MASK << (fromIndex % BITS_PER_WORD));
 
         while (true) {
             if (word != 0)
                 return (u * BITS_PER_WORD) + numberOfTrailingZeros(word);
             if (++u == words.size())
                 return -1;
             word = words[u];
         }
     }

bool epics::pvData::BitSet::operator!= ( const BitSet & set ) const

Definition at line 310 of file bitSet.cpp.

     {
         return !(*this == set);
     }

BitSet & epics::pvData::BitSet::operator&= ( const BitSet & set )

Performs a bitwise AND of this target bit set with the argument bit set. This bit set is modified so that each bit in it has the value true if and only if it both initially had the value true and the corresponding bit in the bit set argument also had the value true.

Parameters

set a bit set

Definition at line 228 of file bitSet.cpp.

                                                 {
         // Check for self-assignment!
         if (this == &set) return *this;
 
         // the result length will be <= the shorter of the two inputs
         words.resize(std::min(words.size(), set.words.size()), 0);
 
         for(size_t i=0, e=words.size(); i<e; i++)
             words[i] &= set.words[i];
 
         recalculateWordsInUse();
         return *this;
     }

BitSet & epics::pvData::BitSet::operator= ( const BitSet & set )

Assignment operator.

Definition at line 269 of file bitSet.cpp.

                                                {
         // Check for self-assignment!
         if (this != &set) {
             words = set.words;
         }
         return *this;
     }

bool epics::pvData::BitSet::operator== ( const BitSet & set ) const

Comparison operator.

Definition at line 294 of file bitSet.cpp.

     {
         if (this == &set)
             return true;
 
         if (words.size() != set.words.size())
             return false;
 
         // Check words in use by both BitSets
         for (uint32 i = 0; i < words.size(); i++)
             if (words[i] != set.words[i])
                 return false;
 
         return true;
     }

BitSet & epics::pvData::BitSet::operator^= ( const BitSet & set )

Performs a bitwise XOR of this bit set with the bit set argument. This bit set is modified so that a bit in it has the value true if and only if one of the following statements holds:

The bit initially has the value true, and the corresponding bit in the argument has the value false.
The bit initially has the value false, and the corresponding bit in the argument has the value true.

Parameters

set a bit set

Definition at line 257 of file bitSet.cpp.

                                                 {
         // result length will <= the longer of the two inputs
         words.resize(std::max(words.size(), set.words.size()), 0);
 
         for(size_t i=0, e=set.words.size(); i<e; i++)
             words[i] ^= set.words[i];
 
         recalculateWordsInUse();
         return *this;
     }

BitSet & epics::pvData::BitSet::operator|= ( const BitSet & set )

Performs a bitwise OR of this bit set with the bit set argument. This bit set is modified so that a bit in it has the value true if and only if it either already had the value true or the corresponding bit in the bit set argument has the value true.

Parameters

set a bit set

Definition at line 242 of file bitSet.cpp.

                                                 {
         // Check for self-assignment!
         if (this == &set) return *this;
 
         // result length will be the same as the longer of the two inputs
         words.resize(std::max(words.size(), set.words.size()), 0);
 
         // since we expand w/ zeros, then iterate using the size of the other vector
         for(size_t i=0, e=set.words.size(); i<e; i++)
             words[i] |= set.words[i];
 
         CHECK_POST();
         return *this;
     }

void epics::pvData::BitSet::or_and	(	const BitSet &	set1,
		const BitSet &	set2
	)

Perform AND operation on set1 and set2, and OR on result and this instance.

Parameters

set1
set2

Definition at line 282 of file bitSet.cpp.

                                                               {
 
         const size_t andlen = std::min(set1.words.size(), set2.words.size());
         words.resize(std::max(words.size(), andlen), 0);
 
         // Perform logical AND on words in common
         for (uint32 i = 0; i < andlen; i++)
             words[i] |= (set1.words[i] & set2.words[i]);
 
         recalculateWordsInUse();
     }

epics::pvData::BitSet::POINTER_DEFINITIONS ( BitSet )

void epics::pvData::BitSet::serialize	(	ByteBuffer *	buffer,
		SerializableControl *	flusher
	)		const

virtual

Serialize field into given buffer.

Parameters

buffer	serialization buffer.
flusher	flush interface.

Implements epics::pvData::Serializable.

Definition at line 315 of file bitSet.cpp.

                                                                                  {
 
         uint32 n = words.size();
         if (n == 0) {
             SerializeHelper::writeSize(0, buffer, flusher);
             return;
         }
         uint32 len = BYTES_PER_WORD * (n-1); // length excluding bits in the last word
         // count non-zero bytes in the last word
         for (uint64 x = words[n - 1]; x != 0; x >>= 8)
             len++;
 
         SerializeHelper::writeSize(len, buffer, flusher);
         flusher->ensureBuffer(len);
 
         n = len / 8;
         for (uint32 i = 0; i < n; i++)
             buffer->putLong(words[i]);
 
         if (n < words.size())
             for (uint64 x = words[words.size() - 1]; x != 0; x >>= 8)
                 buffer->putByte((int8) (x & 0xff));
     }

BitSet & epics::pvData::BitSet::set ( uint32 bitIndex )

Sets the bit at the specified index to true.

Parameters

bitIndex a bit index

Definition at line 103 of file bitSet.cpp.

                                        {
 
         uint32 wordIdx = WORD_INDEX(bitIndex);
         expandTo(wordIdx);
 
         words[wordIdx] |= (((uint64)1) << WORD_OFFSET(bitIndex));
         return *this;
     }

void epics::pvData::BitSet::set	(	uint32	bitIndex,
		bool	value
	)

Sets the bit at the specified index to the specified value.

Parameters

bitIndex	a bit index
value	a boolean value to set

Definition at line 123 of file bitSet.cpp.

                                                 {
         if (value)
             set(bitIndex);
         else
             clear(bitIndex);
     }

uint32 epics::pvData::BitSet::size ( ) const

Returns the number of bits of space actually in use by this BitSet to represent bit values. The maximum element in the set is the size - 1st element.

Returns: the number of bits currently in this bit set

Definition at line 210 of file bitSet.cpp.

                               {
         return words.size() * BITS_PER_WORD;
     }

void epics::pvData::BitSet::swap ( BitSet & set )

Swap contents.

Definition at line 277 of file bitSet.cpp.

     {
         words.swap(set.words);
     }

The documentation for this class was generated from the following files:

modules/pvData/src/misc/pv/bitSet.h
modules/pvData/src/misc/bitSet.cpp

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation