Sifteo::BitArray< tSize > Class Template Reference

A fixed-size array of bits, with compact storage and fast iteration. More...

#include <sifteo/array.h>

Classes
struct	iterator
	An STL-style iterator for the BitArray. More...

Public Member Functions
iterator	begin () const
	Return an STL-style iterator for this array.
	BitArray ()
	Create a new empty BitArray.
	BitArray (unsigned index)
	Create a new BitArray with a single bit marked.
	BitArray (unsigned begin, unsigned end)
	Create a new BitArray with a range of bits marked. More...
void	clear (unsigned index)
	Clear (set to 0) a single bit.
void	clear ()
	Clear (set to 0) all bits in the array.
bool	clearFirst (unsigned &index)
	Find and clear the lowest marked bit. More...
bool	clearN (unsigned &index, unsigned n)
	Find and clear the Nth lowest marked bit. More...
unsigned	count () const
	How many bits are marked in this vector?
bool	empty () const
	Is every bit in this array set to zero?
iterator	end () const
	Return an STL-style iterator for this array.
bool	findFirst (unsigned &index) const
	Find the lowest index where there's a marked (1) bit. More...
void	mark (unsigned index)
	Mark (set to 1) a single bit.
void	mark ()
	Mark (set to 1) all bits in the array.
BitArray< tSize >	operator& (const BitArray< tSize > &other) const
	Bitwise AND of two BitArrays of the same size.
BitArray< tSize >	operator^ (const BitArray< tSize > &other) const
	Bitwise XOR of two BitArrays of the same size.
BitArray< tSize >	operator| (const BitArray< tSize > &other) const
	Bitwise OR of two BitArrays of the same size.
BitArray< tSize >	operator~ () const
	Negate a BitArray, returning a new array in which each bit is inverted.
bool	test (unsigned index) const
	Is a particular bit marked?

Static Public Member Functions
static unsigned	size ()
	Retrieve the size of this array in bits, always constant at compile-time.

Detailed Description

template<unsigned tSize>
class Sifteo::BitArray< tSize >

A fixed-size array of bits, with compact storage and fast iteration.

Supports arrays with any fixed-size number of bits. For sizes <= 32 bits, this is just as efficient as using a bare uint32_t.

This is a Plain Old Data type, with no constructor.

The default value of the bits in a BitArray is undefined. Initialize the BitArray prior to use, for example by calling mark() or clear().

BitArrays support iteration, through explicit method calls or via C++11 range-based for loops.

Constructor & Destructor Documentation

template<unsigned tSize>

Sifteo::BitArray< tSize >::BitArray ( unsigned  begin, unsigned  end  )

inlineexplicit

Create a new BitArray with a range of bits marked.

This is a half-open interval. All bits >= 'begin' and < 'end' are marked.

Member Function Documentation

template<unsigned tSize>

bool Sifteo::BitArray< tSize >::clearFirst ( unsigned &  index )

inline

Find and clear the lowest marked bit.

If we find any marked bits, returns true, sets "index" to that bit's index, and clears the bit. This can be used as part of an iteration pattern:

  unsigned index;
  while (vec.clearFirst(index)) {
      doStuff(index);
  }

This is functionally equivalent to findFirst() followed by clear(), but it's a tiny bit more efficient.

template<unsigned tSize>

bool Sifteo::BitArray< tSize >::clearN ( unsigned &  index, unsigned  n  )

inline

Find and clear the Nth lowest marked bit.

For n=0, this is equivalent to clearFirst(). For n=1, we skip the first marked bit and clear the second. And so on. If there is no Nth marked bit, returns false.

template<unsigned tSize>

bool Sifteo::BitArray< tSize >::findFirst ( unsigned &  index ) const

inline

Find the lowest index where there's a marked (1) bit.

If any marked bits exist, returns true and puts the bit's index in "index". Iff the entire array is zero, returns false.

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

• array.h