caching kign position

4 files changed, 37 insertions, 17 deletions

diff --git a/src/board/board.cpp b/src/board/board.cpp
index 2cd705d..572a3f0 100644
--- a/src/board/board.cpp
+++ b/src/board/board.cpp
@@ -2,21 +2,32 @@
 #include "moves.hpp"
 #include "zobrist.hpp"
 #include <cassert>
+#include <cstdint>
 #include <cstdlib>
 
 int PositionToIndex(Position i) { return i.rank * 8 + i.file; }
 
 Position FindKing(Game *b, bool color) {
-  for (int i = 0; i < 64; i++) {
-    Piece piece = b->pieces[i];
-
-    if (piece.type == KING && piece.color == color) {
-      return IndexToPosition(i);
-    }
+  if (b->WhiteKingPosition >= 64) {
+    assert(false && "weird position");
+    exit(1);
   }
-
-  assert(false && "King not found");
-  return {0, 0};
+  if (b->BlackKingPosition >= 64) {
+    assert(false && "weird position");
+    exit(1);
+  }
+  if (b->pieces[b->WhiteKingPosition].color != true ||
+      b->pieces[b->WhiteKingPosition].type != KING) {
+    assert(false && "Expected king at king position");
+    exit(1);
+  }
+  if (b->pieces[b->BlackKingPosition].color != false ||
+      b->pieces[b->BlackKingPosition].type != KING) {
+    assert(false && "Expected king at king position");
+    exit(1);
+  }
+  return color ? IndexToPosition(b->WhiteKingPosition)
+               : IndexToPosition(b->BlackKingPosition);
 }
 UndoMove MakeMove(Move move, Game *g) {
   UndoMove undo = {};
@@ -188,7 +199,7 @@ UndoMove MakeMove(Move move, Game *g) {
   if (g->halfMoveClock >= 50) {
     g->state = DRAW;
   }
-  UpdateBitboards(g);
+  UpdateHelpers(g);
   return undo;
 };
 void UnMakeMove(UndoMove undo, Game *g) {
@@ -244,15 +255,22 @@ void UnMakeMove(UndoMove undo, Game *g) {
   if (g->ThreeFoldMap[undo.ZobristKey] <= 0) {
     g->ThreeFoldMap.erase(undo.ZobristKey);
   };
-  UpdateBitboards(g);
+  UpdateHelpers(g);
 };
-void UpdateBitboards(Game *g) {
+void UpdateHelpers(Game *g) {
   g->PieceBitboard = 0;
-  for (int i = 0; i < 64; i++) {
+  for (uint8_t i = 0; i < 64; i++) {
     Piece piece = g->pieces[i];
     if (piece.type == NONEPIECE) {
       continue;
     }
+    if (piece.type == KING) {
+      if (piece.color) {
+        g->WhiteKingPosition = i;
+      } else {
+        g->BlackKingPosition = i;
+      }
+    }
     g->PieceBitboard |= (1ULL << i);
   }
 }
diff --git a/src/board/board.hpp b/src/board/board.hpp
index bcd0b95..869e223 100644
--- a/src/board/board.hpp
+++ b/src/board/board.hpp
@@ -53,7 +53,9 @@ struct TranspositionsEntry {
 struct Game {
   Piece pieces[64];
   uint64_t PieceBitboard = 0; // used for quicly iterating over all squares
-  bool turn = true;           // 1 white; 0 black
+  uint8_t WhiteKingPosition = 0;
+  uint8_t BlackKingPosition = 0;
+  bool turn = true; // 1 white; 0 black
   bool whiteCastleKing = false;
   bool whiteCastleQueen = false;
   bool blackCastleKing = false;
@@ -102,6 +104,6 @@ UndoMove MakeMove(Move move, Game *g);
 void UnMakeMove(UndoMove undo, Game *g);
 
 Position FindKing(Game *g, bool white);
-void UpdateBitboards(Game *g);
+void UpdateHelpers(Game *g);
 void SetPiece(int i, PieceType type, bool color, Game *g);
 #endif /* SRC_BOARD_H_ */
diff --git a/src/board/fen.cpp b/src/board/fen.cpp
index a7e65eb..fc52bfe 100644
--- a/src/board/fen.cpp
+++ b/src/board/fen.cpp
@@ -154,5 +154,5 @@ void setBoardFen(const std::string fen, Game *g) {
     break;
   }
   g->enPassant = enpassant;
-  UpdateBitboards(g);
+  UpdateHelpers(g);
 }
diff --git a/src/bot.cpp b/src/bot.cpp
index cffa202..3567ef3 100644
--- a/src/bot.cpp
+++ b/src/bot.cpp
@@ -254,7 +254,7 @@ Move GetBestMove(Game *b, const int maxDepth) {
   Nodes = 0;
 
   int actualDepth = maxDepth > 0 ? maxDepth : MAXIMUM_DEPTH;
-  bool usingDefaultDepth = maxDepth > 0;
+  bool usingDefaultDepth = maxDepth < 0;
   auto legalMoves = GetSortedLegalMoves(b, true, nullptr);
   if (legalMoves.empty()) {
     assert(false && "GetBestMove called with no legal moves");