/// Mate with KX vs K. This function is used to evaluate positions with
-/// King and plenty of material vs a lone king. It simply gives the
+/// king and plenty of material vs a lone king. It simply gives the
/// attacking side a bonus for driving the defending king towards the edge
/// of the board, and for keeping the distance between the two kings small.
template<>
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 so to drive enemy toward corners A8 or H1.
+ // 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))
{
winnerKSq = ~winnerKSq;
}
-/// KQ vs KP. In general, a win for the stronger side, however, there are a few
-/// important exceptions. Pawn on 7th rank, A,C,F or H file, with king next can
-/// be a draw, so we scale down to distance between kings only.
+/// KQ vs KP. In general, this is a win for the stronger side, but there are a
+/// few important exceptions. A pawn on 7th rank and on the A,C,F or H files
+/// with a king positioned next to it can be a draw, so in that case, we only
+/// use the distance between the kings.
template<>
Value Endgame<KQKP>::operator()(const Position& pos) const {
return SCALE_FACTOR_DRAW;
}
- // All pawns on same B or G file? Then potential draw
+ // If all the pawns are on the same B or G file, then it's potentially a draw
if ( (pawnFile == FILE_B || pawnFile == FILE_G)
&& !(pos.pieces(PAWN) & ~file_bb(pawnFile))
&& pos.non_pawn_material(weakSide) == 0
&& pos.count<PAWN>(weakSide) >= 1)
{
- // Get weakSide pawn that is closest to home rank
+ // Get weakSide pawn that is closest to the home rank
Square weakPawnSq = backmost_sq(weakSide, pos.pieces(weakSide, PAWN));
Square strongKingSq = pos.king_square(strongSide);
Square weakKingSq = pos.king_square(weakSide);
Square bishopSq = pos.list<BISHOP>(strongSide)[0];
- // 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)))
int strongKingDist = square_distance(weakPawnSq, strongKingSq);
int weakKingDist = square_distance(weakPawnSq, weakKingSq);
- // Draw if the weak king is on it's back two ranks, within 2
+ // It's a draw if the weak king is on its back two ranks, within 2
// squares of the blocking pawn and the strong king is not
// closer. (I think this rule only fails in practically
// unreachable positions such as 5k1K/6p1/6P1/8/8/3B4/8/8 w
/// 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 not very pretty.
+/// which is mostly copied from Glaurung 1.x, and isn't very pretty.
template<>
ScaleFactor Endgame<KRPKR>::operator()(const Position& pos) const {
switch (file_distance(psq1, psq2))
{
case 0:
- // Both pawns are on the same file. Easy draw if defender firmly controls
- // some square in the frontmost pawn's path.
+ // Both pawns are on the same file. It's an easy draw if the defender firmly
+ // controls some square in the frontmost pawn's path.
if ( file_of(ksq) == file_of(blockSq1)
&& relative_rank(strongSide, ksq) >= relative_rank(strongSide, blockSq1)
&& opposite_colors(ksq, wbsq))
return SCALE_FACTOR_NONE;
case 1:
- // Pawns on adjacent files. Draw if defender firmly controls the square
- // in front of the frontmost pawn's path, and the square diagonally behind
- // this square on the file of the other pawn.
+ // Pawns on adjacent files. It's a draw if the defender firmly controls the
+ // square in front of the frontmost pawn's path, and the square diagonally
+ // behind this square on the file of the other pawn.
if ( ksq == blockSq1
&& opposite_colors(ksq, wbsq)
&& ( bbsq == blockSq2