Update ratings + minor fixes

Author: herohde

README.md

@@ -1,27 +1,26 @@
 # morlock
 
 Morlock is a hobbyist chess engine in Go. It supports a few standard techniques and protocols and
-is currently mainly used to re-implement a few historical engines, TUROCHAMP (1948) and SARGON (1978).
-These historical engine re-implementations can be played on [lichess.org](lichess.org). They are
-available 24/7 at various search depths.
+is currently mainly used to re-implement the following historical chess engines:
 
-TUROCHAMP (1948) by Alan Turing and David Champernowne. It uses a full search with an unbounded
+### TUROCHAMP (1948) by Alan Turing and David Champernowne
+
+Turochamp uses a full search with an unbounded
 quiescence search of "considerable moves" using material ratio and position play heuristics:
 
-*  [turochamp-1ply](https://lichess.org/@/turochamp-1ply). Rating ~1400 (blitz/rapid).
-*  [turochamp-2ply](https://lichess.org/@/turochamp-2ply). Rating ~1500 (blitz/rapid).
+*  [turochamp-1ply](https://lichess.org/@/turochamp-1ply). Rating ~1300 (blitz/rapid).
+*  [turochamp-2ply](https://lichess.org/@/turochamp-2ply). Rating ~1600 (blitz/rapid).
+
+### SARGON (1978) by Dan and Kathe Spracklen
 
-SARGON (1978) by Dan and Kathe Spracklen. It uses a full search with material exchange, king/queen pins
-and board control heuristics:
+Sargon uses a full search with material exchange, king/queen pins and board control heuristics:
 
 *  [sargon-1ply](https://lichess.org/@/sargon-1ply). Rating ~1300 (blitz/rapid).
 *  [sargon-2ply](https://lichess.org/@/sargon-2ply). Rating ~1400 (blitz/rapid).
-*  [sargon-3ply](https://lichess.org/@/sargon-3ply). Rating ~1500 (blitz/rapid).
-*  [sargon-4ply](https://lichess.org/@/sargon-4ply). Rating ~1600 (blitz/rapid).
-
-These engines each have quirks, blind spots and limitations, which is part of their charm. They play
-at low search depths to entertain rather than win.
+*  [sargon-3ply](https://lichess.org/@/sargon-3ply). Rating ~1700 (blitz/rapid).
+*  [sargon-4ply](https://lichess.org/@/sargon-4ply). Rating ~1800 (blitz/rapid).
 
-Enjoy!
+Each engine can be played 24/7 for free on [lichess.org](https://lichess.org). They have quirks, blind spots and limitations,
+which is part of their charm -- and play at low search depths to entertain rather than win.
 
-_June 2021_
+_September 2022_

pkg/board/bitboard.go

@@ -135,7 +135,7 @@ func init() {
 	}
 }
 
-// KnighAttackboard returns all potential moves/attacks for a Knight at the given square.
+// KnightAttackboard returns all potential moves/attacks for a Knight at the given square.
 func KnightAttackboard(sq Square) Bitboard {
 	return knight[sq]
 }

pkg/board/board.go

@@ -247,15 +247,15 @@ func (b *Board) LastMove() (Move, bool) {
 	return Move{}, false
 }
 
-// LastMove returns the second-to-last move, if any.
+// SecondToLastMove returns the second-to-last move, if any.
 func (b *Board) SecondToLastMove() (Move, bool) {
 	if b.current.prev != nil && b.current.prev.prev != nil {
 		return b.current.prev.prev.next, true
 	}
 	return Move{}, false
 }
 
-// HasCasted returns true iff the color has castled.
+// HasCastled returns true iff the color has castled.
 func (b *Board) HasCastled(c Color) bool {
 	return b.hasCastled[c]
 }

pkg/board/position.go

@@ -388,26 +388,3 @@ func safeCastlingSquares(c Color, t MoveType) []Square {
 		}
 	}
 }
-
-// rookSquares return the rook squares for castling.
-func rookSquares(c Color, t MoveType) []Square {
-	if c == White {
-		switch t {
-		case KingSideCastle:
-			return []Square{F1, H1}
-		case QueenSideCastle:
-			return []Square{A1, D1}
-		default:
-			return nil
-		}
-	} else {
-		switch t {
-		case KingSideCastle:
-			return []Square{F8, H8}
-		case QueenSideCastle:
-			return []Square{A8, D8}
-		default:
-			return nil
-		}
-	}
-}

pkg/eval/score.go

@@ -97,7 +97,7 @@ func (s Score) MateDistance() (int8, bool) {
 	}
 }
 
-// Negates returns the negative score, as viewed from the opponent.
+// Negate returns the negative score, as viewed from the opponent.
 func (s Score) Negate() Score {
 	switch s.Type {
 	case Heuristic: