Micro optimize count_1s_max_15() for 32 bit system

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index bc1900196d45cbc0c901158506096460195b426d..1140664838b47bfb875a4a4841b7c07f90c1e7e3 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -8,6 +8,7 @@
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
+
   Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ -112,8 +113,8 @@ extern const Bitboard RankBB[8];
 extern const Bitboard RelativeRankBB[2][8];
 extern const Bitboard InFrontBB[2][8];
 
-extern Bitboard SetMaskBB[64];
-extern Bitboard ClearMaskBB[64];
+extern Bitboard SetMaskBB[65];
+extern Bitboard ClearMaskBB[65];
 
 extern Bitboard StepAttackBB[16][64];
 extern Bitboard RayBB[64][8];
@@ -150,26 +151,16 @@ extern Bitboard QueenPseudoAttacks[64];
 /// Functions for testing whether a given bit is set in a bitboard, and for
 /// setting and clearing bits.
 
-inline Bitboard set_mask_bb(Square s) {
-  //  return 1ULL << s;
-  return SetMaskBB[s];
-}
-
-inline Bitboard clear_mask_bb(Square s) {
-  //  return ~set_mask_bb(s);
-  return ClearMaskBB[s];
-}
-
 inline Bitboard bit_is_set(Bitboard b, Square s) {
-  return b & set_mask_bb(s);
+  return b & SetMaskBB[s];
 }
 
 inline void set_bit(Bitboard *b, Square s) {
-  *b |= set_mask_bb(s);
+  *b |= SetMaskBB[s];
 }
 
 inline void clear_bit(Bitboard *b, Square s) {
-  *b &= clear_mask_bb(s);
+  *b &= ClearMaskBB[s];
 }
 
 
@@ -245,6 +236,19 @@ inline Bitboard in_front_bb(Color c, Square s) {
 }
 
 
+/// behind_bb() takes a color and a rank or square as input, and returns a
+/// bitboard representing all the squares on all ranks behind of the rank
+/// (or square), from the given color's point of view.
+
+inline Bitboard behind_bb(Color c, Rank r) {
+  return InFrontBB[opposite_color(c)][r];
+}
+
+inline Bitboard behind_bb(Color c, Square s) {
+  return in_front_bb(opposite_color(c), square_rank(s));
+}
+
+
 /// ray_bb() gives a bitboard representing all squares along the ray in a
 /// given direction from a given square.
 
@@ -393,11 +397,10 @@ inline int count_1s(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
   v = v - ((v >> 1) & 0x55555555);
   w = w - ((w >> 1) & 0x55555555);
+  v += w;
   v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
-  w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
   v = (v + (v >> 4)) & 0x0F0F0F0F;
-  w = (w + (w >> 4)) & 0x0F0F0F0F;
-  v = ((v+w) * 0x01010101) >> 24; // mul is fast on amd procs
+  v = (v * 0x01010101) >> 24; // mul is fast on amd procs
   return int(v);
 }
 
@@ -405,9 +408,9 @@ inline int count_1s_max_15(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
   v = v - ((v >> 1) & 0x55555555);
   w = w - ((w >> 1) & 0x55555555);
+  v += w;
   v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
-  w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
-  v = ((v+w) * 0x11111111) >> 28;
+  v = (v * 0x11111111) >> 28;
   return int(v);
 }