Generate pseudo-legal moves in generate_evasions()

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index e30629186fdb65ec9321c1fbb72c064cba268814..be4e234d99d9b937036ee9d6fabb9cec170a0e40 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -470,7 +470,6 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   assert(is_ok());
   assert(move_is_ok(m));
   assert(pinned == pinned_pieces(side_to_move()));
-  assert(!is_check());
 
   // Castling moves are checked for legality during move generation.
   if (move_is_castle(m))
@@ -482,7 +481,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   assert(color_of_piece_on(from) == us);
   assert(piece_on(king_square(us)) == piece_of_color_and_type(us, KING));
 
-  // En passant captures are a tricky special case.  Because they are
+  // En passant captures are a tricky special case. Because they are
   // rather uncommon, we do it simply by testing whether the king is attacked
   // after the move is made
   if (move_is_ep(m))
@@ -703,7 +702,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
   // pointer to point to the new, ready to be updated, state.
   struct ReducedStateInfo {
     Key key, pawnKey, materialKey;
-    int castleRights, rule50;
+    int castleRights, rule50, pliesFromNull;
     Square epSquare;
     Value mgValue, egValue;
     Value npMaterial[2];
@@ -724,6 +723,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
   // Increment the 50 moves rule draw counter. Resetting it to zero in the
   // case of non-reversible moves is taken care of later.
   st->rule50++;
+  st->pliesFromNull++;
 
   if (move_is_castle(m))
   {
@@ -1238,11 +1238,11 @@ void Position::do_null_move(StateInfo& backupSt) {
   // Note that differently from normal case here backupSt is actually used as
   // a backup storage not as a new state to be used.
   backupSt.key      = st->key;
-  backupSt.rule50   = st->rule50;
   backupSt.epSquare = st->epSquare;
   backupSt.mgValue  = st->mgValue;
   backupSt.egValue  = st->egValue;
   backupSt.previous = st->previous;
+  backupSt.pliesFromNull = st->pliesFromNull;
   st->previous = &backupSt;
 
   // Save the current key to the history[] array, in order to be able to
@@ -1258,7 +1258,8 @@ void Position::do_null_move(StateInfo& backupSt) {
 
   sideToMove = opposite_color(sideToMove);
   st->epSquare = SQ_NONE;
-  st->rule50 = 0;
+  st->rule50++;
+  st->pliesFromNull = 0;
   gamePly++;
 
   st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
@@ -1276,14 +1277,15 @@ void Position::undo_null_move() {
   // Restore information from the our backup StateInfo object
   StateInfo* backupSt = st->previous;
   st->key      = backupSt->key;
-  st->rule50   = backupSt->rule50;
   st->epSquare = backupSt->epSquare;
   st->mgValue  = backupSt->mgValue;
   st->egValue  = backupSt->egValue;
   st->previous = backupSt->previous;
+  st->pliesFromNull = backupSt->pliesFromNull;
 
   // Update the necessary information
   sideToMove = opposite_color(sideToMove);
+  st->rule50--;
   gamePly--;
 }
 
@@ -1335,6 +1337,7 @@ int Position::see(Square from, Square to) const {
 
   Bitboard attackers, stmAttackers, b;
 
+  assert(!shortcut || from != SQ_NONE);
   assert(square_is_ok(from) || from == SQ_NONE);
   assert(square_is_ok(to));
 
@@ -1347,6 +1350,10 @@ int Position::see(Square from, Square to) const {
   Piece capture = piece_on(to);
   Bitboard occ = occupied_squares();
 
+  // King cannot be recaptured
+  if (type_of_piece(piece) == KING)
+      return seeValues[capture];
+
   // Handle en passant moves
   if (st->epSquare == to && type_of_piece_on(from) == PAWN)
   {
@@ -1485,8 +1492,8 @@ void Position::clear() {
   for (int i = 0; i < 64; i++)
       board[i] = EMPTY;
 
-  for (int i = 0; i < 7; i++)
-      for (int j = 0; j < 8; j++)
+  for (int i = 0; i < 8; i++)
+      for (int j = 0; j < 16; j++)
           pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
 
   sideToMove = WHITE;
@@ -1684,7 +1691,7 @@ bool Position::is_draw() const {
       return true;
 
   // Draw by repetition?
-  for (int i = 2; i < Min(gamePly, st->rule50); i += 2)
+  for (int i = 2; i < Min(Min(gamePly, st->rule50), st->pliesFromNull); i += 2)
       if (history[gamePly - i] == st->key)
           return true;
 
@@ -1698,8 +1705,7 @@ bool Position::is_draw() const {
 bool Position::is_mate() const {
 
   MoveStack moves[256];
-
-  return is_check() && (generate_evasions(*this, moves, pinned_pieces(sideToMove)) == moves);
+  return is_check() && (generate_moves(*this, moves, false) == moves);
 }