Rewrite some bitboard init code

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index 033964b75b3d9c657e997d5e9b9b566284303172..349005787fd402d6ab958818f46e1262fc4b8356 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -18,7 +18,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#if !defined(BITBOARD_H_INCLUDED)
+#ifndef BITBOARD_H_INCLUDED
 #define BITBOARD_H_INCLUDED
 
 #include "types.h"
@@ -74,6 +74,7 @@ extern Bitboard AdjacentFilesBB[FILE_NB];
 extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
 extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
 extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard DistanceRingsBB[SQUARE_NB][8];
 extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
 extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
@@ -82,7 +83,7 @@ extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
 
 extern int SquareDistance[SQUARE_NB][SQUARE_NB];
 
-const Bitboard BlackSquares = 0xAA55AA55AA55AA55ULL;
+const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
 
 /// Overloads of bitwise operators between a Bitboard and a Square for testing
 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
@@ -156,7 +157,7 @@ inline Bitboard file_bb(Square s) {
 }
 
 
-/// adjacent_files_bb takes a file as input and returns a bitboard representing
+/// adjacent_files_bb() takes a file as input and returns a bitboard representing
 /// all squares on the adjacent files.
 
 inline Bitboard adjacent_files_bb(File f) {
@@ -174,7 +175,7 @@ inline Bitboard in_front_bb(Color c, Rank r) {
 }
 
 
-/// between_bb returns a bitboard representing all squares between two squares.
+/// between_bb() returns a bitboard representing all squares between two squares.
 /// For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with the bits for
 /// square d5 and e6 set.  If s1 and s2 are not on the same line, file or diagonal,
 /// 0 is returned.
@@ -184,7 +185,7 @@ inline Bitboard between_bb(Square s1, Square s2) {
 }
 
 
-/// forward_bb takes a color and a square as input, and returns a bitboard
+/// forward_bb() takes a color and a square as input, and returns a bitboard
 /// representing all squares along the line in front of the square, from the
 /// point of view of the given color. Definition of the table is:
 /// ForwardBB[c][s] = in_front_bb(c, s) & file_bb(s)
@@ -194,40 +195,39 @@ inline Bitboard forward_bb(Color c, Square s) {
 }
 
 
-/// passed_pawn_mask takes a color and a square as input, and returns a
+/// pawn_attack_span() takes a color and a square as input, and returns a bitboard
+/// representing all squares that can be attacked by a pawn of the given color
+/// when it moves along its file starting from the given square. Definition is:
+/// PawnAttackSpan[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
+
+inline Bitboard pawn_attack_span(Color c, Square s) {
+  return PawnAttackSpan[c][s];
+}
+
+
+/// passed_pawn_mask() takes a color and a square as input, and returns a
 /// bitboard mask which can be used to test if a pawn of the given color on
 /// the given square is a passed pawn. Definition of the table is:
-/// PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(s)
+/// PassedPawnMask[c][s] = pawn_attack_span(c, s) | forward_bb(c, s)
 
 inline Bitboard passed_pawn_mask(Color c, Square s) {
   return PassedPawnMask[c][s];
 }
 
 
-/// attack_span_mask takes a color and a square as input, and returns a bitboard
-/// representing all squares that can be attacked by a pawn of the given color
-/// when it moves along its file starting from the given square. Definition is:
-/// AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(s);
+/// squares_of_color() returns a bitboard representing all squares with the same
+/// color of the given square.
 
-inline Bitboard pawn_attack_span(Color c, Square s) {
-  return PawnAttackSpan[c][s];
+inline Bitboard squares_of_color(Square s) {
+  return DarkSquares & s ? DarkSquares : ~DarkSquares;
 }
 
 
-/// squares_aligned returns true if the squares s1, s2 and s3 are aligned
+/// aligned() returns true if the squares s1, s2 and s3 are aligned
 /// either on a straight or on a diagonal line.
 
-inline bool squares_aligned(Square s1, Square s2, Square s3) {
-  return  (BetweenBB[s1][s2] | BetweenBB[s1][s3] | BetweenBB[s2][s3])
-        & (     SquareBB[s1] |      SquareBB[s2] |      SquareBB[s3]);
-}
-
-
-/// same_color_squares() returns a bitboard representing all squares with
-/// the same color of the given square.
-
-inline Bitboard same_color_squares(Square s) {
-  return BlackSquares & s ? BlackSquares : ~BlackSquares;
+inline bool aligned(Square s1, Square s2, Square s3) {
+  return LineBB[s1][s2] & s3;
 }
 
 
@@ -254,11 +254,21 @@ inline Bitboard attacks_bb(Square s, Bitboard occ) {
   return (Pt == ROOK ? RAttacks : BAttacks)[s][magic_index<Pt>(s, occ)];
 }
 
+inline Bitboard attacks_bb(Piece p, Square s, Bitboard occ) {
+
+  switch (type_of(p))
+  {
+  case BISHOP: return attacks_bb<BISHOP>(s, occ);
+  case ROOK  : return attacks_bb<ROOK>(s, occ);
+  case QUEEN : return attacks_bb<BISHOP>(s, occ) | attacks_bb<ROOK>(s, occ);
+  default    : return StepAttacksBB[p][s];
+  }
+}
 
 /// lsb()/msb() finds the least/most significant bit in a nonzero bitboard.
 /// pop_lsb() finds and clears the least significant bit in a nonzero bitboard.
 
-#if defined(USE_BSFQ)
+#ifdef USE_BSFQ
 
 #  if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
 
@@ -311,7 +321,7 @@ FORCE_INLINE Square pop_lsb(Bitboard* b) {
   return s;
 }
 
-#else // if !defined(USE_BSFQ)
+#else // if defined(USE_BSFQ)
 
 extern Square msb(Bitboard b);
 extern Square lsb(Bitboard b);
@@ -319,4 +329,10 @@ extern Square pop_lsb(Bitboard* b);
 
 #endif
 
-#endif // !defined(BITBOARD_H_INCLUDED)
+/// frontmost_sq() and backmost_sq() find the square corresponding to the
+/// most/least advanced bit relative to the given color.
+
+inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); }
+inline Square  backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); }
+
+#endif // #ifndef BITBOARD_H_INCLUDED