Add passed pawn evaluation

Author: ArcticXWolf

.goreleaser.yml

@@ -14,9 +14,8 @@ archives:
       linux: linux
       windows: windows
       386: i386
-      amd64: x86_64
     format: binary
-    name_template: "{{ tolower .ProjectName }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}"
+    name_template: "{{ tolower .ProjectName }}_{{ .Os }}_{{ .Arch }}"
 checksum:
   name_template: 'checksums.txt'
 snapshot:

Makefile

@@ -3,7 +3,7 @@ BUILD=`date +%FT%T%z`
 COMMIT=`git rev-list -1 HEAD`
 BINARY=axwchessbot
 
-LDFLAGS=-ldflags "-w -s -X main.engineVersion=${VERSION} -X main.buildDate=${BUILD} -X main.gitCommit=${COMMIT}"
+LDFLAGS=-ldflags "-w -s -X main.version=${VERSION} -X main.date=${BUILD} -X main.commit=${COMMIT}"
 
 build:
 	echo "Building for linux and windows"

README.md

@@ -37,6 +37,7 @@ implemented.
     * Tempo evaluation
     * Pair bonus
     * Rook on (half-)open files bonus
+    * Passed pawn bonus
 * Simple search algorithm using
     * Negamax with alpha-beta-pruning
     * Quiescence search
@@ -49,7 +50,6 @@ implemented.
 * Evaluation improvements
     * Pawnshield bonus
     * Blocked piece penalty
-    * Passed pawn bonus
 * Search improvements
     * Killer move heuristics
     * Multiprocessing (Lazy SMP?)

evaluation/evaluation.go

@@ -103,6 +103,7 @@ func calculateEvaluationPart(g *game.Game, color game.PlayerColor) EvaluationPar
 		PairModifier:            calculatePairModifier(g, color),
 		TempoModifier:           calculateTempoModifier(g, color),
 		RookFileModifier:        calculateRookModifier(g, color),
+		PassedPawnModifier:      calculatePassedPawns(g, color),
 	}
 	return evalPart
 }
@@ -215,15 +216,29 @@ func calculateRookModifier(g *game.Game, color game.PlayerColor) (result int) {
 	return rooksOnOpenFiles*weights[color].AdditionalModifier.OpenRookModifier + rooksOnHalfOpenFiles*weights[color].AdditionalModifier.HalfRookModifier
 }
 
-func calculatePawnFileFill(pawnBitboard uint64) uint64 {
-	// Northfill
-	pawnBitboard |= (pawnBitboard << 8)
-	pawnBitboard |= (pawnBitboard << 16)
-	pawnBitboard |= (pawnBitboard << 32)
-	// Southfill
-	pawnBitboard |= (pawnBitboard >> 8)
-	pawnBitboard |= (pawnBitboard >> 16)
-	pawnBitboard |= (pawnBitboard >> 32)
-
-	return pawnBitboard
+func calculatePassedPawns(g *game.Game, color game.PlayerColor) (result int) {
+	if color == game.White {
+		frontSpansBlack := calculatePawnSouthFill(g.Position.Black.Pawns) & ^g.Position.Black.Pawns
+		attackingSpansBlack := frontSpansBlack
+		attackingSpansBlack |= (frontSpansBlack << 1) & ^bitboardFileA //shift everything east and care for wraps
+		attackingSpansBlack |= (frontSpansBlack >> 1) & ^bitboardFileH //shift everything west and care for wraps
+		whitePassedPawns := g.Position.White.Pawns & ^attackingSpansBlack
+		for x := whitePassedPawns; x != 0; x &= x - 1 {
+			square := bits.TrailingZeros64(x)
+			result += weights[color].Midgame.PassedPawnModifier[square]
+		}
+		return
+	}
+
+	//black
+	frontSpansWhite := calculatePawnNorthFill(g.Position.White.Pawns) & ^g.Position.White.Pawns
+	attackingSpansWhite := frontSpansWhite
+	attackingSpansWhite |= (frontSpansWhite << 1) & ^bitboardFileA //shift everything east and care for wraps
+	attackingSpansWhite |= (frontSpansWhite >> 1) & ^bitboardFileH //shift everything west and care for wraps
+	blackPassedPawns := g.Position.Black.Pawns & ^attackingSpansWhite
+	for x := blackPassedPawns; x != 0; x &= x - 1 {
+		square := bits.TrailingZeros64(x)
+		result += weights[color].Midgame.PassedPawnModifier[square]
+	}
+	return
 }

evaluation/evaluation_test.go

@@ -217,3 +217,91 @@ func TestCalculateEvaluation(t *testing.T) {
 		})
 	}
 }
+
+func Test_calculatePairModifier(t *testing.T) {
+	type args struct {
+		g     *game.Game
+		color game.PlayerColor
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{"GameStart White", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.White}, 6},
+		{"GameStart Black", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.Black}, 6},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := calculatePairModifier(tt.args.g, tt.args.color); got != tt.want {
+				t.Errorf("calculatePairModifier() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_calculateTempoModifier(t *testing.T) {
+	type args struct {
+		g     *game.Game
+		color game.PlayerColor
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{"GameStart White", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.White}, 10},
+		{"GameStart Black", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.Black}, 0},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := calculateTempoModifier(tt.args.g, tt.args.color); got != tt.want {
+				t.Errorf("calculateTempoModifier() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_calculateRookModifier(t *testing.T) {
+	type args struct {
+		g     *game.Game
+		color game.PlayerColor
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{"GameStart White", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.White}, 0},
+		{"GameStart Black", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.Black}, 0},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := calculateRookModifier(tt.args.g, tt.args.color); got != tt.want {
+				t.Errorf("calculateRookModifier() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_calculatePassedPawns(t *testing.T) {
+	type args struct {
+		g     *game.Game
+		color game.PlayerColor
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{"GameStart White", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.White}, 0},
+		{"GameStart Black", args{game.NewFromFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"), game.Black}, 0},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := calculatePassedPawns(tt.args.g, tt.args.color); got != tt.want {
+				t.Errorf("calculatePassedPawns() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

evaluation/utils.go

@@ -0,0 +1,26 @@
+package evaluation
+
+var (
+	bitboardFileA uint64 = 0x0101010101010101
+	bitboardFileH uint64 = 0x8080808080808080
+)
+
+func calculatePawnFileFill(pawnBitboard uint64) uint64 {
+	pawnBitboard |= calculatePawnNorthFill(pawnBitboard)
+	pawnBitboard |= calculatePawnSouthFill(pawnBitboard)
+	return pawnBitboard
+}
+
+func calculatePawnNorthFill(pawnBitboard uint64) uint64 {
+	pawnBitboard |= (pawnBitboard << 8)
+	pawnBitboard |= (pawnBitboard << 16)
+	pawnBitboard |= (pawnBitboard << 32)
+	return pawnBitboard
+}
+
+func calculatePawnSouthFill(pawnBitboard uint64) uint64 {
+	pawnBitboard |= (pawnBitboard >> 8)
+	pawnBitboard |= (pawnBitboard >> 16)
+	pawnBitboard |= (pawnBitboard >> 32)
+	return pawnBitboard
+}

evaluation/weights.go

@@ -18,8 +18,9 @@ type AdditionalModifier struct {
 }
 
 type GamephaseWeights struct {
-	Material          map[dragontoothmg.Piece]int
-	PieceSquareTables map[dragontoothmg.Piece][64]int
+	Material           map[dragontoothmg.Piece]int
+	PassedPawnModifier [64]int
+	PieceSquareTables  map[dragontoothmg.Piece][64]int
 }
 
 type Weights struct {
@@ -49,6 +50,16 @@ var (
 			dragontoothmg.Queen:  900,
 			dragontoothmg.King:   0,
 		},
+		PassedPawnModifier: [64]int{
+			0, 0, 0, 0, 0, 0, 0, 0,
+			10, 10, 10, 10, 10, 10, 10, 10,
+			20, 20, 20, 20, 20, 20, 20, 20,
+			40, 40, 40, 40, 40, 40, 40, 40,
+			60, 60, 60, 60, 60, 60, 60, 60,
+			80, 80, 80, 80, 80, 80, 80, 80,
+			100, 100, 100, 100, 100, 100, 100, 100,
+			0, 0, 0, 0, 0, 0, 0, 0,
+		},
 		PieceSquareTables: map[dragontoothmg.Piece][64]int{
 			dragontoothmg.Pawn: [64]int{
 				0, 0, 0, 0, 0, 0, 0, 0,
@@ -116,11 +127,13 @@ var (
 
 var (
 	midgameWeights = GamephaseWeights{
-		Material:          weightsForAllPhases.Material,
-		PieceSquareTables: weightsForAllPhases.PieceSquareTables,
+		Material:           weightsForAllPhases.Material,
+		PassedPawnModifier: weightsForAllPhases.PassedPawnModifier,
+		PieceSquareTables:  weightsForAllPhases.PieceSquareTables,
 	}
 	endgameWeights = GamephaseWeights{
-		Material: weightsForAllPhases.Material,
+		Material:           weightsForAllPhases.Material,
+		PassedPawnModifier: weightsForAllPhases.PassedPawnModifier,
 		PieceSquareTables: map[dragontoothmg.Piece][64]int{
 			dragontoothmg.Pawn:   weightsForAllPhases.PieceSquareTables[dragontoothmg.Pawn],
 			dragontoothmg.Knight: weightsForAllPhases.PieceSquareTables[dragontoothmg.Knight],
@@ -160,7 +173,8 @@ var (
 		},
 		game.Black: Weights{
 			Midgame: GamephaseWeights{
-				Material: midgameWeights.Material,
+				Material:           midgameWeights.Material,
+				PassedPawnModifier: flipPstArrayVertically(midgameWeights.PassedPawnModifier),
 				PieceSquareTables: map[dragontoothmg.Piece][64]int{
 					dragontoothmg.Pawn:   flipPstArrayVertically(midgameWeights.PieceSquareTables[dragontoothmg.Pawn]),
 					dragontoothmg.Knight: flipPstArrayVertically(midgameWeights.PieceSquareTables[dragontoothmg.Knight]),
@@ -171,7 +185,8 @@ var (
 				},
 			},
 			Endgame: GamephaseWeights{
-				Material: endgameWeights.Material,
+				Material:           endgameWeights.Material,
+				PassedPawnModifier: flipPstArrayVertically(endgameWeights.PassedPawnModifier),
 				PieceSquareTables: map[dragontoothmg.Piece][64]int{
 					dragontoothmg.Pawn:   flipPstArrayVertically(endgameWeights.PieceSquareTables[dragontoothmg.Pawn]),
 					dragontoothmg.Knight: flipPstArrayVertically(endgameWeights.PieceSquareTables[dragontoothmg.Knight]),

search/search_test.go

@@ -112,7 +112,7 @@ func TestProblematicGames(t *testing.T) {
 			"Test QuiescenceSearch on Errors concerning no available moves",
 			fields{
 				"e2e4 e7e5 g1f3 b8c6 f1b5 a7a6 b5c6 d7c6 e1g1 d8f6 d2d4 e5d4 c1g5 f6d6 f3d4 c6c5 d4f3 d6d1 f1d1 f7f6 g5f4 g7g5 f4c7 c8g4 b1d2 e8d7 f3e5 f6e5 c7e5 g4d1 a1d1 d7e7 e5h8 a8d8 h8c3 b7b5 c3a5 d8d4 a5c3 d4d6 b2b4 d6g6 b4c5 e7e8 d2b3 g5g4 d1d3 g6e6 f2f3 f8e7 h2h3 g4f3 g2f3 e6c6 d3d5 e7f6 c3f6 c6f6 b3d4 b5b4 c5c6 g8e7 c6c7 e7c8 d5d8 e8e7 d8c8 e7d7 c8b8 d7c7 b8b4 a6a5 b4b5 f6d6 c2c3 a5a4 b5a5",
-				7,
+				4,
 				4,
 			},
 		},

search/transposition_table.go

@@ -14,6 +14,7 @@ const (
 	alphaBetaBoundUpper
 )
 
+// 96 bits = 12 Bytes
 type transpositionTableEntry struct {
 	lock  int32
 	move  dragontoothmg.Move
@@ -23,23 +24,28 @@ type transpositionTableEntry struct {
 }
 
 type TranspositionTable struct {
-	maxSize int
-	entries map[uint64]transpositionTableEntry
+	maxSizeInEntries int
+	entries          map[uint64]transpositionTableEntry
 }
 
-// 1 entry is 20 bytes
-func NewTranspositionTable(maxSize int) *TranspositionTable {
+// 1 entry is 12 bytes
+func NewTranspositionTable(maxSizeInBytes int) *TranspositionTable {
+	maxSizeInEntries := maxSizeInBytes / 12
 	return &TranspositionTable{
-		maxSize: maxSize,
-		entries: make(map[uint64]transpositionTableEntry, maxSize),
+		maxSizeInEntries: maxSizeInEntries,
+		entries:          make(map[uint64]transpositionTableEntry, maxSizeInEntries),
 	}
 }
 
 func (tt *TranspositionTable) Empty() {
-	tt.entries = make(map[uint64]transpositionTableEntry, tt.maxSize)
+	tt.entries = make(map[uint64]transpositionTableEntry, tt.maxSizeInEntries)
 }
 
 func (tt *TranspositionTable) InsertIfNeeded(hash uint64, move dragontoothmg.Move, score int, depth int, bound alphaBetaBound) {
+	if len(tt.entries) >= tt.maxSizeInEntries {
+		tt.Empty()
+	}
+
 	entry, found := tt.entries[hash]
 
 	if !found {

uci/timemanager.go

@@ -48,7 +48,7 @@ func NewTimingInfo(messageParts []string) (timingInfo *UciTimingInfo) {
 	return
 }
 
-func (timingInfo *UciTimingInfo) calculateTimeoutContext(ctx context.Context, g *game.Game) (context.Context, func()) {
+func (timingInfo *UciTimingInfo) calculateTimeoutContext(ctx context.Context, g *game.Game, options []UciOption) (context.Context, func()) {
 	if timingInfo.MovesToGo <= 0 && timingInfo.TimeWhite <= 0 && timingInfo.TimeBlack <= 0 {
 		return context.WithCancel(ctx)
 	}
@@ -62,7 +62,24 @@ func (timingInfo *UciTimingInfo) calculateTimeoutContext(ctx context.Context, g
 		timeLeft, increment = time.Duration(timingInfo.TimeBlack)*time.Millisecond, time.Duration(timingInfo.IncrementBlack)*time.Millisecond
 	}
 
-	timeLeft -= MoveOverhead
+	moveOverhead := MoveOverhead
+	maxTime := MaxTime
+	for _, option := range options {
+		if option.name == "Move Overhead" {
+			optionsMO, err := strconv.Atoi(option.value)
+			if err == nil {
+				moveOverhead = time.Duration(optionsMO) * time.Millisecond
+			}
+		}
+		if option.name == "Max Time" {
+			optionsMT, err := strconv.Atoi(option.value)
+			if err == nil {
+				maxTime = time.Duration(optionsMT) * time.Second
+			}
+		}
+	}
+
+	timeLeft -= moveOverhead
 	if timeLeft <= 0 {
 		timeLeft = 0
 	}
@@ -73,8 +90,8 @@ func (timingInfo *UciTimingInfo) calculateTimeoutContext(ctx context.Context, g
 	if limit > timeLeft-MinTimeLeft {
 		limit = timeLeft - MinTimeLeft
 	}
-	if limit > MaxTime {
-		limit = MaxTime
+	if limit > maxTime {
+		limit = maxTime
 	}
 
 	return context.WithDeadline(ctx, timingInfo.StartTimestamp.Add(limit))