feat: chess960 castling and perft tests

chess/castling.go

@@ -99,9 +99,9 @@ func newCastleCheck(c Color, s side, kings [2]Square, cf [2]File, cr castlingRig
  rook1 := newSquare(cf[s], castleRank[c])
  rook2 := newSquare(rookFinalFile[s], castleRank[c])
 
- bbKingTravel := bbInBetweens[king1][king2] | king2.bitboard()
- bbRookTravel := bbInBetweens[rook1][rook2] | rook2.bitboard()
- bbNoCheck := bbKingTravel | king1.bitboard()
+ bbKingTravel := (bbInBetweens[king1][king2] | (king2.bitboard() & ^king1.bitboard())) & ^rook1.bitboard()
+ bbRookTravel := (bbInBetweens[rook1][rook2] | (rook2.bitboard() & ^rook1.bitboard())) & ^king1.bitboard()
+ bbNoCheck := bbInBetweens[king1][king2] | king1.bitboard() | king2.bitboard()
 
  var bbNoEnemyPawn, bbNoEnemyKnight, bbNoEnemyKing bitboard
  for bb := bbNoCheck; bb > 0; bb = bb.resetLSB() {

chess/castling_test.go

@@ -23,3 +23,98 @@ func TestCastling_String(t *testing.T) {
  })
  }
 }
+
+func TestNewCastleCheck(t *testing.T) {
+ type args struct {
+ c Color
+ s side
+ kings [2]Square
+ cf [2]File
+ cr castlingRights
+ }
+
+ all := castleBlackA | castleBlackH | castleWhiteA | castleWhiteH
+
+ tests := []struct {
+ name string
+ fen string
+ args
+ want castleCheck
+ }{
+ {
+ "Chess960 580",
+ "qbb1rkrn/1ppppppp/p7/7n/8/P2P4/1PP1PPPP/QBBRNKRN w Gg - 0 9",
+ args{White, hSide, [2]Square{F8, F1}, [2]File{FileD, FileG}, castleWhiteH},
+ castleCheck{
+ bbKingTravel: bbEmpty,
+ bbRookTravel: bbEmpty,
+ bbNoEnemyPawn: 61440,
+ bbNoEnemyKnight: 15767552,
+ bbNoEnemyKing: 61680,
+ bbNoCheck: F1.bitboard() | G1.bitboard(),
+ king1: F1,
+ king2: G1,
+ rook1: G1,
+ rook2: F1,
+ },
+ },
+ {
+ "Chess960 865",
+ "bqkr1rnn/1ppp1ppp/p4b2/4p3/P7/3PP2N/1PP2PPP/BQRBKR1N w FC - 3 9",
+ args{White, hSide, [2]Square{C8, E1}, [2]File{FileC, FileF}, castleWhiteA | castleWhiteH},
+ castleCheck{
+ bbKingTravel: G1.bitboard(),
+ bbRookTravel: bbEmpty,
+ bbNoEnemyPawn: 63488,
+ bbNoEnemyKnight: 16309248,
+ bbNoEnemyKing: 63736,
+ bbNoCheck: E1.bitboard() | F1.bitboard() | G1.bitboard(),
+ king1: E1,
+ king2: G1,
+ rook1: F1,
+ rook2: F1,
+ },
+ },
+ {
+ "Chess960 877",
+ "qrk1rnb1/p1pp1ppp/1p2Bbn1/8/4P3/6P1/PPPP1P1P/QRK1RNBN w EBeb - 1 9",
+ args{White, aSide, [2]Square{C8, C1}, [2]File{FileB, FileE}, all},
+ castleCheck{
+ bbKingTravel: bbEmpty,
+ bbRookTravel: D1.bitboard(),
+ bbNoEnemyPawn: 2560,
+ bbNoEnemyKnight: 659712,
+ bbNoEnemyKing: 3594,
+ bbNoCheck: C1.bitboard(),
+ king1: C1,
+ king2: C1,
+ rook1: B1,
+ rook2: D1,
+ },
+ },
+ {
+ "Chess960 944",
+ "b2krn1q/p1rppppp/1Q3n2/2p1b3/1P4P1/8/P1PPPP1P/BBRKRNN1 w - - 3 9",
+ args{White, aSide, [2]Square{D8, D1}, [2]File{FileC, FileE}, castleBlackH | castleWhiteA | castleWhiteH},
+ castleCheck{
+ bbKingTravel: bbEmpty,
+ bbRookTravel: bbEmpty,
+ bbNoEnemyPawn: 7680,
+ bbNoEnemyKnight: 1979136,
+ bbNoEnemyKing: 7710,
+ bbNoCheck: C1.bitboard() | D1.bitboard(),
+ king1: D1,
+ king2: C1,
+ rook1: C1,
+ rook2: D1,
+ },
+ },
+ }
+
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ got := newCastleCheck(tt.c, tt.s, tt.kings, tt.cf, tt.cr)
+ assert.Equal(t, tt.want, got)
+ })
+ }
+}

chess/perft.go

@@ -79,7 +79,7 @@ func perft(pos *Position, depth int) int {
  return nodes
 }
 
-// String implements fmt.Stringer.
+// String implements the Stringer interface.
 //
 // Returns the perft result as an output accepted by the perftree cli.
 func (pr PerftResult) String() string {
@@ -91,7 +91,7 @@ func (pr PerftResult) String() string {
  return b.String()
 }
 
-// String implements fmt.Stringer.
+// String implements the Stringer interface.
 //
 // Returns the move in UCI notation followed by a space, then the number of nodes
 // of which this move is an ancestor.