Skip castle rights update when not needed

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index 4d132e033244e602fd0f1edfeedfe3244a7759fe..c17c5c5757e550680ee9929e144dcbf5bf3f2216 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -27,6 +27,7 @@
 #include <fstream>
 #include <iostream>
 
+#include "bitcount.h"
 #include "mersenne.h"
 #include "movegen.h"
 #include "movepick.h"
@@ -314,9 +315,10 @@ void Position::print(Move m) const {
 
 /// Position::copy() creates a copy of the input position.
 
-void Position::copy(const Position &pos) {
+void Position::copy(const Position& pos) {
 
   memcpy(this, &pos, sizeof(Position));
+  saveState(); // detach and copy state info
 }
 
 
@@ -741,12 +743,11 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
       do_capture_move(st->capture, them, to);
 
     // Move the piece
-    clear_bit(&(byColorBB[us]), from);
-    clear_bit(&(byTypeBB[piece]), from);
-    clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
-    set_bit(&(byColorBB[us]), to);
-    set_bit(&(byTypeBB[piece]), to);
-    set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+    Bitboard move_bb = make_move_bb(from, to);
+    do_move_bb(&(byColorBB[us]), move_bb);
+    do_move_bb(&(byTypeBB[piece]), move_bb);
+    do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
+
     board[to] = board[from];
     board[from] = EMPTY;
 
@@ -795,11 +796,14 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
     pieceList[us][piece][index[from]] = to;
     index[to] = index[from];
 
-    // Update castle rights
-    st->key ^= zobCastle[st->castleRights];
-    st->castleRights &= castleRightsMask[from];
-    st->castleRights &= castleRightsMask[to];
-    st->key ^= zobCastle[st->castleRights];
+    // Update castle rights, try to shortcut a common case
+    if ((castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES)
+    {
+        st->key ^= zobCastle[st->castleRights];
+        st->castleRights &= castleRightsMask[from];
+        st->castleRights &= castleRightsMask[to];
+        st->key ^= zobCastle[st->castleRights];
+    }
 
     // Update checkers bitboard, piece must be already moved
     st->checkersBB = EmptyBoardBB;
@@ -838,6 +842,7 @@ void Position::do_capture_move(PieceType capture, Color them, Square to) {
     // Remove captured piece
     clear_bit(&(byColorBB[them]), to);
     clear_bit(&(byTypeBB[capture]), to);
+    clear_bit(&(byTypeBB[0]), to);
 
     // Update hash key
     st->key ^= zobrist[them][capture][to];
@@ -1080,21 +1085,17 @@ void Position::do_ep_move(Move m) {
   assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
   assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
 
-  // Remove captured piece
+  // Remove captured pawn
   clear_bit(&(byColorBB[them]), capsq);
   clear_bit(&(byTypeBB[PAWN]), capsq);
   clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares
   board[capsq] = EMPTY;
 
-  // Remove moving piece from source square
-  clear_bit(&(byColorBB[us]), from);
-  clear_bit(&(byTypeBB[PAWN]), from);
-  clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
-
-  // Put moving piece on destination square
-  set_bit(&(byColorBB[us]), to);
-  set_bit(&(byTypeBB[PAWN]), to);
-  set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+  // Move capturing pawn
+  Bitboard move_bb = make_move_bb(from, to);
+  do_move_bb(&(byColorBB[us]), move_bb);
+  do_move_bb(&(byTypeBB[PAWN]), move_bb);
+  do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
   board[to] = board[from];
   board[from] = EMPTY;
 
@@ -1170,17 +1171,13 @@ void Position::undo_move(Move m) {
       assert(color_of_piece_on(to) == us);
 
       // Put the piece back at the source square
+      Bitboard move_bb = make_move_bb(to, from);
       piece = type_of_piece_on(to);
-      set_bit(&(byColorBB[us]), from);
-      set_bit(&(byTypeBB[piece]), from);
-      set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
+      do_move_bb(&(byColorBB[us]), move_bb);
+      do_move_bb(&(byTypeBB[piece]), move_bb);
+      do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
       board[from] = piece_of_color_and_type(us, piece);
 
-      // Clear the destination square
-      clear_bit(&(byColorBB[us]), to);
-      clear_bit(&(byTypeBB[piece]), to);
-      clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
-
       // If the moving piece was a king, update the king square
       if (piece == KING)
           kingSquare[us] = from;
@@ -1193,7 +1190,7 @@ void Position::undo_move(Move m) {
       {
           assert(st->capture != KING);
 
-          // Replace the captured piece
+          // Restore the captured piece
           set_bit(&(byColorBB[them]), to);
           set_bit(&(byTypeBB[st->capture]), to);
           set_bit(&(byTypeBB[0]), to);
@@ -1375,22 +1372,18 @@ void Position::undo_ep_move(Move m) {
   assert(piece_on(from) == EMPTY);
   assert(piece_on(capsq) == EMPTY);
 
-  // Replace captured piece
+  // Restore captured pawn
   set_bit(&(byColorBB[them]), capsq);
   set_bit(&(byTypeBB[PAWN]), capsq);
   set_bit(&(byTypeBB[0]), capsq);
   board[capsq] = piece_of_color_and_type(them, PAWN);
 
-  // Remove moving piece from destination square
-  clear_bit(&(byColorBB[us]), to);
-  clear_bit(&(byTypeBB[PAWN]), to);
-  clear_bit(&(byTypeBB[0]), to);
+  // Move capturing pawn back to source square
+  Bitboard move_bb = make_move_bb(to, from);
+  do_move_bb(&(byColorBB[us]), move_bb);
+  do_move_bb(&(byTypeBB[PAWN]), move_bb);
+  do_move_bb(&(byTypeBB[0]), move_bb);
   board[to] = EMPTY;
-
-  // Replace moving piece at source square
-  set_bit(&(byColorBB[us]), from);
-  set_bit(&(byTypeBB[PAWN]), from);
-  set_bit(&(byTypeBB[0]), from);
   board[from] = piece_of_color_and_type(us, PAWN);
 
   // Update piece list
@@ -1604,7 +1597,7 @@ int Position::see(Square from, Square to) const {
       if (pt == KING && stmAttackers)
       {
           assert(n < 32);
-          swapList[n++] = 100;
+          swapList[n++] = QueenValueMidgame*10;
           break;
       }
   } while (stmAttackers);
@@ -1618,15 +1611,16 @@ int Position::see(Square from, Square to) const {
 }
 
 
-/// Position::setStartState() copies the content of the argument
+/// Position::saveState() copies the content of the current state
 /// inside startState and makes st point to it. This is needed
 /// when the st pointee could become stale, as example because
 /// the caller is about to going out of scope.
 
-void Position::setStartState(const StateInfo& s) {
+void Position::saveState() {
 
-  startState = s;
+  startState = *st;
   st = &startState;
+  st->previous = NULL; // as a safe guard
 }
 
 
@@ -1977,7 +1971,7 @@ void Position::init_piece_square_tables() {
 /// the white and black sides reversed. This is only useful for debugging,
 /// especially for finding evaluation symmetry bugs.
 
-void Position::flipped_copy(const Position &pos) {
+void Position::flipped_copy(const Position& pos) {
 
   assert(pos.is_ok());