board

type Board struct {
	// TODO: move occupancies into one array? Possible memory speed boost
	// White to move. 1=true, 0=false. Use uint because bools cannot be xor'd
	WToMove uint
	Zobrist uint64

	Pieces  [2]uint64
	Pawns   [2]uint64
	Knights [2]uint64
	Bishops [2]uint64
	Rooks   [2]uint64
	Queens  [2]uint64
	Kings   [2]uint64

	KingSqs      [2]int8
	CastleRights [2][2]bool // [b, w][queenside, kingside]

	EpSquare  int8
	PrevMove  Move
	HalfMoves uint8

	EvalMaterial   int
	PiecePhaseSum  int
	EvalMidGamePST int // piece-square tables (PST)
	EvalEndGamePST int
}

type IntArray interface {
	[8]int8 | [4]int8 | [3]int8
}

type Move struct {
	From, To         int8
	Piece, PromoteTo uint8
}

type Position struct {
	WToMove uint
	Zobrist uint64

	Pieces  [2]uint64
	Pawns   [2]uint64
	Knights [2]uint64
	Bishops [2]uint64
	Rooks   [2]uint64
	Queens  [2]uint64
	Kings   [2]uint64

	KingSqs      [2]int8
	CastleRights [2][2]bool

	EpSquare  int8
	PrevMove  Move
	HalfMoves uint8

	EvalMaterial   int
	PiecePhaseSum  int
	EvalMidGamePST int
	EvalEndGamePST int
}

type Zobrist struct {
	ColorPieceSq [2][6][64]uint64
	BToMove      uint64
	Castle       [2][2]uint64
	EpFile       [8]uint64
}