X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=0ee0a6eb840bf2b0eabe740b0d1faf13d50e4ee5;hp=976b3d6365c46d4316784bb3ea078af54924e0b7;hb=431c3ac485386cc10413fc8a3c7d338dcc71602d;hpb=190aea4cdc6e8e165028803be846563da53f9330

diff --git a/src/endgame.cpp b/src/endgame.cpp
index 976b3d63..0ee0a6eb 100644
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -80,10 +80,10 @@ namespace {
     return sq;
   }
 
-  // Get the material key of a Position out of the given endgame key code
-  // like "KBPKN". The trick here is to first forge an ad-hoc fen string
-  // and then let a Position object to do the work for us. Note that the
-  // fen string could correspond to an illegal position.
+  // Get the material key of Position out of the given endgame key code
+  // like "KBPKN". The trick here is to first forge an ad-hoc FEN string
+  // and then let a Position object do the work for us. Note that the
+  // FEN string could correspond to an illegal position.
   Key key(const string& code, Color c) {
 
     assert(code.length() > 0 && code.length() < 8);
@@ -187,8 +187,8 @@ Value Endgame<KBNK>::operator()(const Position& pos) const {
   Square loserKSq = pos.king_square(weakSide);
   Square bishopSq = pos.list<BISHOP>(strongSide)[0];
 
-  // kbnk_mate_table() tries to drive toward corners A1 or H8, if we have a
-  // bishop that cannot reach the above squares we flip the kings in order
+  // kbnk_mate_table() tries to drive toward corners A1 or H8. If we have a
+  // bishop that cannot reach the above squares, we flip the kings in order
   // to drive the enemy toward corners A8 or H1.
   if (opposite_colors(bishopSq, SQ_A1))
   {
@@ -286,7 +286,7 @@ Value Endgame<KRKB>::operator()(const Position& pos) const {
 }
 
 
-/// KR vs KN.  The attacking side has slightly better winning chances than
+/// KR vs KN. The attacking side has slightly better winning chances than
 /// in KR vs KB, particularly if the king and the knight are far apart.
 template<>
 Value Endgame<KRKN>::operator()(const Position& pos) const {
@@ -328,9 +328,8 @@ Value Endgame<KQKP>::operator()(const Position& pos) const {
 
 /// KQ vs KR.  This is almost identical to KX vs K:  We give the attacking
 /// king a bonus for having the kings close together, and for forcing the
-/// defending king towards the edge.  If we also take care to avoid null move
-/// for the defending side in the search, this is usually sufficient to be
-/// able to win KQ vs KR.
+/// defending king towards the edge. If we also take care to avoid null move for
+/// the defending side in the search, this is usually sufficient to win KQ vs KR.
 template<>
 Value Endgame<KQKR>::operator()(const Position& pos) const {
 
@@ -349,7 +348,7 @@ Value Endgame<KQKR>::operator()(const Position& pos) const {
 }
 
 
-/// KBB vs KN. This is almost always a win. We try to push enemy king to a corner
+/// KBB vs KN. This is almost always a win. We try to push the enemy king to a corner
 /// and away from his knight. For a reference of this difficult endgame see:
 /// en.wikipedia.org/wiki/Chess_endgame#Effect_of_tablebases_on_endgame_theory
 
@@ -377,7 +376,7 @@ template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE
 template<> Value Endgame<KmmKm>::operator()(const Position&) const { return VALUE_DRAW; }
 
 
-/// K, bishop and one or more pawns vs K. It checks for draws with rook pawns and
+/// KB and one or more pawns vs K. It checks for draws with rook pawns and
 /// a bishop of the wrong color. If such a draw is detected, SCALE_FACTOR_DRAW
 /// is returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling
 /// will be used.
@@ -419,7 +418,7 @@ ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
       Square weakKingSq = pos.king_square(weakSide);
       Square bishopSq = pos.list<BISHOP>(strongSide)[0];
 
-      // There's potential for a draw if our pawn is blocked on the 7th rank
+      // There's potential for a draw if our pawn is blocked on the 7th rank,
       // the bishop cannot attack it or they only have one pawn left
       if (   relative_rank(strongSide, weakPawnSq) == RANK_7
           && (pos.pieces(strongSide, PAWN) & (weakPawnSq + pawn_push(weakSide)))
@@ -445,8 +444,8 @@ ScaleFactor Endgame<KBPsK>::operator()(const Position& pos) const {
 }
 
 
-/// K and queen vs K, rook and one or more pawns. It tests for fortress draws with
-/// a rook on the third rank defended by a pawn.
+/// KQ vs KR and one or more pawns. It tests for fortress draws with a rook on
+/// the third rank defended by a pawn.
 template<>
 ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
 
@@ -469,9 +468,9 @@ ScaleFactor Endgame<KQKRPs>::operator()(const Position& pos) const {
 }
 
 
-/// K, rook and one pawn vs K and a rook. This function knows a handful of the
-/// most important classes of drawn positions, but is far from perfect. It would
-/// probably be a good idea to add more knowledge in the future.
+/// KRP vs KR. This function knows a handful of the most important classes of
+/// drawn positions, but is far from perfect. It would probably be a good idea
+/// to add more knowledge in the future.
 ///
 /// It would also be nice to rewrite the actual code for this function,
 /// which is mostly copied from Glaurung 1.x, and isn't very pretty.
@@ -556,7 +555,7 @@ ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
                          - 8 * square_distance(wpsq, queeningSq)
                          - 2 * square_distance(wksq, queeningSq));
 
-  // If the pawn is not far advanced, and the defending king is somewhere in
+  // If the pawn is not far advanced and the defending king is somewhere in
   // the pawn's path, it's probably a draw.
   if (r <= RANK_4 && bksq > wpsq)
   {
@@ -613,9 +612,8 @@ ScaleFactor Endgame<KRPKB>::operator()(const Position& pos) const {
   return SCALE_FACTOR_NONE;
 }
 
-/// K, rook and two pawns vs K, rook and one pawn. There is only a single
-/// pattern: If the stronger side has no passed pawns and the defending king
-/// is actively placed, the position is drawish.
+/// KRPP vs KRP. There is just a single rule: if the stronger side has no passed
+/// pawns and the defending king is actively placed, the position is drawish.
 template<>
 ScaleFactor Endgame<KRPPKRP>::operator()(const Position& pos) const {
 
@@ -662,8 +660,8 @@ ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
   Bitboard pawns = pos.pieces(strongSide, PAWN);
   Square psq = pos.list<PAWN>(strongSide)[0];
 
-  // If all pawns are ahead of the king, all pawns are on a single
-  // rook file and the king is within one file of the pawns then draw.
+  // If all pawns are ahead of the king, on a single rook file and
+  // the king is within one file of the pawns, it's a draw.
   if (   !(pawns & ~in_front_bb(weakSide, rank_of(ksq)))
       && !((pawns & ~FileABB) && (pawns & ~FileHBB))
       && file_distance(ksq, psq) <= 1)
@@ -673,10 +671,10 @@ ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
 }
 
 
-/// K, bishop and a pawn vs K and a bishop. There are two rules: If the defending
-/// king is somewhere along the path of the pawn, and the square of the king is
-/// not of the same color as the stronger side's bishop, it's a draw. If the two
-/// bishops have opposite color, it's almost always a draw.
+/// KBP vs KB. There are two rules: if the defending king is somewhere along the
+/// path of the pawn, and the square of the king is not of the same color as the
+/// stronger side's bishop, it's a draw. If the two bishops have opposite color,
+/// it's almost always a draw.
 template<>
 ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
 
@@ -726,8 +724,7 @@ ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
 }
 
 
-/// K, bishop and two pawns vs K and bishop. It detects a few basic draws with
-/// opposite-colored bishops.
+/// KBPP vs KB. It detects a few basic draws with opposite-colored bishops
 template<>
 ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
 
@@ -796,9 +793,9 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
 }
 
 
-/// K, bisop and a pawn vs K and knight. There is a single rule: If the defending
-/// king is somewhere along the path of the pawn, and the square of the king is
-/// not of the same color as the stronger side's bishop, it's a draw.
+/// KBP vs KN. There is a single rule: If the defending king is somewhere along
+/// the path of the pawn, and the square of the king is not of the same color as
+/// the stronger side's bishop, it's a draw.
 template<>
 ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
 
@@ -819,9 +816,8 @@ ScaleFactor Endgame<KBPKN>::operator()(const Position& pos) const {
 }
 
 
-/// K, knight and a pawn vs K. There is a single rule: If the pawn is a rook pawn
-/// on the 7th rank and the defending king prevents the pawn from advancing, the
-/// position is drawn.
+/// KNP vs K. There is a single rule: if the pawn is a rook pawn on the 7th rank
+/// and the defending king prevents the pawn from advancing the position is drawn.
 template<>
 ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
 
@@ -839,8 +835,8 @@ ScaleFactor Endgame<KNPK>::operator()(const Position& pos) const {
 }
 
 
-/// K, knight and a pawn vs K and bishop. If knight can block bishop from taking
-/// pawn, it's a win. Otherwise, drawn.
+/// KNP vs KB. If knight can block bishop from taking pawn, it's a win.
+/// Otherwise the position is drawn.
 template<>
 ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
 
@@ -857,11 +853,11 @@ ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
 }
 
 
-/// K and a pawn vs K and a pawn. This is done by removing the weakest side's
-/// pawn and probing the KP vs K bitbase: If the weakest side has a draw without
-/// the pawn, she probably has at least a draw with the pawn as well. The exception
-/// is when the stronger side's pawn is far advanced and not on a rook file; in
-/// this case it is often possible to win (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1).
+/// KP vs KP. This is done by removing the weakest side's pawn and probing the
+/// KP vs K bitbase: If the weakest side has a draw without the pawn, it probably
+/// has at least a draw with the pawn as well. The exception is when the stronger
+/// side's pawn is far advanced and not on a rook file; in this case it is often
+/// possible to win (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1).
 template<>
 ScaleFactor Endgame<KPKP>::operator()(const Position& pos) const {