Chess::Zobrist Class Reference

Unsigned 64-bit values for generating zobrist position keys. More...

#include <zobrist.h>

Inheritance diagram for Chess::Zobrist:

Public Member Functions
virtual void	initialize (int squareCount, int pieceTypeCount)
bool	isInitialized () const
virtual quint64	piece (const Piece &piece, int square) const
virtual quint64	reservePiece (const Piece &piece, int slot) const
virtual quint64	side () const
	Zobrist (const quint64 *keys=nullptr)
virtual	~Zobrist ()

Protected Member Functions
const quint64 *	keys () const
int	pieceTypeCount () const
int	squareCount () const

Static Protected Member Functions
static quint64	random64 ()

Detailed Description

Unsigned 64-bit values for generating zobrist position keys.

Chess::Board uses zobrist keys to quickly and easily compare two positions for equality. Primary uses for zobrist keys are:

• Detecting repetitions, ie. a draw by three-fold repetition
• Opening books
• In hash table entries

Constructor & Destructor Documentation

Zobrist()

Chess::Zobrist::Zobrist

(

const quint64 *

keys = nullptr

)

Creates a new uninitialized Zobrist object.

Parameters

keys	An array of zobrist keys that can be used instead of the random numbers generated by the Zobrist class.

~Zobrist()

virtual Chess::Zobrist::~Zobrist ( )

inlinevirtual

Destroys the Zobrist object.

Member Function Documentation

initialize()

void Chess::Zobrist::initialize ( int squareCount, int pieceTypeCount )

virtual

Initializes the zobrist numbers.

Parameters

squareCount	The number of squares the board has, including the invisible "Wall" squares.
pieceTypeCount	The number of piece types the variant has, including the empty "NoPiece" type (type 0).

Note

Subclasses that reimplement this function must call the base implementation.

Reimplemented in Chess::WesternZobrist.

isInitialized()

bool Chess::Zobrist::isInitialized

(

)

const

Returns true if the keys are initialized.

keys()

const quint64 * Chess::Zobrist::keys ( ) const

inlineprotected

Returns the array of zobrist keys.

piece()

quint64 Chess::Zobrist::piece ( const Piece & piece, int square ) const

virtual

Returns the zobrist value for piece at square.

Reimplemented in Chess::WesternZobrist.

pieceTypeCount()

int Chess::Zobrist::pieceTypeCount ( ) const

inlineprotected

Returns the number of piece types the variant has, including the empty "NoPiece" type (type 0).

random64()

quint64 Chess::Zobrist::random64 ( )

staticprotected

Returns an unsigned 64-bit pseudo-random number.

reservePiece()

quint64 Chess::Zobrist::reservePiece ( const Piece & piece, int slot ) const

virtual

Returns the zobrist value for reserve piece piece at slot.

Note

slot is zero-based, so the first piece of type piece is at slot 0.

side()

quint64 Chess::Zobrist::side ( ) const

virtual

Returns the zobrist value for side to move. This value must be in the key on black's turn.

Reimplemented in Chess::WesternZobrist.

squareCount()

int Chess::Zobrist::squareCount ( ) const

inlineprotected

Returns the number of squares the board has, including the invisible "Wall" squares.

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

• projects/lib/src/board/zobrist.h
• projects/lib/src/board/zobrist.cpp