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Documentation

Index

• func LmpMovesSearched(depth int) int
• func LmrReduction(depth int, movesSearched int) int
• type Limits
  • func NewSearchLimits() *Limits
• type Result
  • func (searchResult *Result) String() string
• type Search
  • func NewSearch() *Search
  • func (s *Search) ClearHash()
  • func (s *Search) GetUciHandlerPtr() uciInterface.UciDriver
  • func (s *Search) IsReady()
  • func (s *Search) IsSearching() bool
  • func (s *Search) LastSearchResult() Result
  • func (s *Search) NewGame()
  • func (s *Search) NodesVisited() uint64
  • func (s *Search) PonderHit()
  • func (s *Search) ResizeCache()
  • func (s *Search) SetUciHandler(uciHandler uciInterface.UciDriver)
  • func (s *Search) StartSearch(p position.Position, sl Limits)
  • func (s *Search) Statistics() *Statistics
  • func (s *Search) StopSearch()
  • func (s *Search) WaitWhileSearching()
• type Statistics
  • func (s *Statistics) String() string

Functions

func LmpMovesSearched

func LmpMovesSearched(depth int) int

LmpMovesSearched returns a depth dependent value for moves searched for late Move Prunings.

func LmrReduction

func LmrReduction(depth int, movesSearched int) int

LmrReduction returns the search depth reduction for LMR depended on depth and moves searched.

Types

type Limits

type Limits struct {
	// no time control
	Infinite bool
	Ponder   bool
	Mate     int

	// extra limits
	Depth int
	Nodes uint64
	Moves moveslice.MoveSlice

	//  time control
	TimeControl bool
	WhiteTime   time.Duration
	BlackTime   time.Duration
	WhiteInc    time.Duration
	BlackInc    time.Duration
	MoveTime    time.Duration

	// parameter
	MovesToGo int
}

Limits is data structure to hold all information about how a search of the chess games shall be controlled. Search needs to read these an determine the necessary limits. E.g. time controlled game or not

func NewSearchLimits

func NewSearchLimits() *Limits

NewSearchLimits creates a new empty Limits instance and returns a pointer to it

type Result

type Result struct {
	BestMove    Move
	BestValue   Value
	PonderMove  Move
	SearchTime  time.Duration
	SearchDepth int
	ExtraDepth  int
	BookMove    bool
	Pv          moveslice.MoveSlice
}

Result stores the result of a search. If BestMove is not MoveNone it can be assumed that all values are valid.

func (*Result) String

func (searchResult *Result) String() string

type Search

type Search struct {
	// contains filtered or unexported fields
}

Search represents the data structure for a chess engine search

Create new instance with NewSearch()

func NewSearch

func NewSearch() *Search

NewSearch creates a new Search instance. If the given uci handler is nil all output will be sent to Stdout.

func (*Search) ClearHash

func (s *Search) ClearHash()

ClearHash clears the transposition table. Is ignored with a warning while searching.

func (*Search) GetUciHandlerPtr

func (s *Search) GetUciHandlerPtr() uciInterface.UciDriver

GetUciHandlerPtr returns the current UciHandler or nil if none is set.

func (*Search) IsReady

func (s *Search) IsReady()

IsReady signals the uciHandler that the search is ready. This is part if the UCI protocol to make sure a chess engine is initialized and ready to receive commands. When called this will initialize the search which might take a while. When finished this will call the uciHandler set in SetUciHandler to send "readyok" to the UCI user interface.

func (*Search) IsSearching

func (s *Search) IsSearching() bool

IsSearching checks if search is running.

func (*Search) LastSearchResult

func (s *Search) LastSearchResult() Result

LastSearchResult returns a copy of the last search result.

func (*Search) NewGame

func (s *Search) NewGame()

NewGame stops any running searches and resets the search state to be ready for a different game. Any caches or states will be reset.

func (*Search) NodesVisited

func (s *Search) NodesVisited() uint64

NodesVisited returns the number of visited nodes in the last search.

func (*Search) PonderHit

func (s *Search) PonderHit()

PonderHit is called by the UCI user interface when the engine has been instructed to ponder before. The engine usually is in search mode without time control when this is sent. This command will then activate time control without interrupting the running search. If no search is running this has no effect.

func (*Search) ResizeCache

func (s *Search) ResizeCache()

ResizeCache resizes and clears the transposition table. Is ignored with a warning while searching.

func (*Search) SetUciHandler

func (s *Search) SetUciHandler(uciHandler uciInterface.UciDriver)

SetUciHandler sets the UCI handler to communicate with the UCI user interface. If not set output will be sent to Stdout.

func (*Search) StartSearch

func (s *Search) StartSearch(p position.Position, sl Limits)

StartSearch starts the search on the given position with the given search limits. Search can be stopped with StopSearch(). Search status can be checked with IsSearching() This takes a copy of the position and the search limits.

func (*Search) Statistics

func (s *Search) Statistics() *Statistics

Statistics returns a pointer to the search statistics of the last search.

func (*Search) StopSearch

func (s *Search) StopSearch()

StopSearch stops a running search as quickly as possible. The search stops gracefully and a result will be sent to UCI. This will wait for the search to be stopped before returning.

func (*Search) WaitWhileSearching

func (s *Search) WaitWhileSearching()

WaitWhileSearching checks if search is running and blocks until search has stopped.

type Statistics

type Statistics struct {
	QFpPrunings uint64

	BestMoveChange       uint64
	AspirationResearches uint64

	BetaCuts    uint64
	BetaCuts1st uint64

	RfpPrunings uint64
	FpPrunings  uint64

	ThreatExtension uint64
	NMPMateAlpha    uint64
	NMPMateBeta     uint64

	CheckExtension uint64
	CheckInQS      uint64

	LmpCuts       uint64
	LmrResearches uint64
	LmrReductions uint64

	Evaluations       uint64
	EvaluationsFromTT uint64

	TTHit      uint64
	TTMiss     uint64
	TTMoveUsed uint64
	NoTTMove   uint64
	TTCuts     uint64
	TTNoCuts   uint64

	IIDmoves    uint64
	IIDsearches uint64

	LeafPositionsEvaluated uint64
	Checkmates             uint64
	Stalemates             uint64
	RootPvsResearches      uint64
	PvsResearches          uint64
	NullMoveCuts           uint64
	StandpatCuts           uint64
	Mdp                    uint64

	CurrentIterationDepth    int
	CurrentSearchDepth       int
	CurrentExtraSearchDepth  int
	CurrentVariation         moveslice.MoveSlice
	CurrentRootMoveIndex     int
	CurrentRootMove          Move
	CurrentBestRootMove      Move
	CurrentBestRootMoveValue Value
}

Statistics are extra data and stats not essential for a functioning search

func (*Statistics) String

func (s *Statistics) String() string