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Lookup square distance instead of calculate on the fly

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Microptimization that gives a +0.7% speed increase.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-09-11 10:00:52 +01:00
parent 6963c3802d
commit b706165527
2 changed files with 10 additions and 4 deletions
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11
src/bitboard.cpp
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@@ -56,6 +56,7 @@ Bitboard RookPseudoAttacks[64];
Bitboard QueenPseudoAttacks[64]; Bitboard QueenPseudoAttacks[64];
uint8_t BitCount8Bit[256]; uint8_t BitCount8Bit[256];
int SquareDistance[64][64];
namespace { namespace {
@@ -154,6 +155,13 @@ Square pop_1st_bit(Bitboard* bb) {
void init_bitboards() { void init_bitboards() {
for (Bitboard b = 0; b < 256; b++)
BitCount8Bit[b] = (uint8_t)count_1s<CNT32_MAX15>(b);
for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
SquareDistance[s1][s2] = Max(file_distance(s1, s2), rank_distance(s1, s2));
SquaresByColorBB[DARK] = 0xAA55AA55AA55AA55ULL; SquaresByColorBB[DARK] = 0xAA55AA55AA55AA55ULL;
SquaresByColorBB[LIGHT] = ~SquaresByColorBB[DARK]; SquaresByColorBB[LIGHT] = ~SquaresByColorBB[DARK];
@@ -194,9 +202,6 @@ void init_bitboards() {
AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s); AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s);
} }
for (Bitboard b = 0; b < 256; b++)
BitCount8Bit[b] = (uint8_t)count_1s<CNT32_MAX15>(b);
for (int i = 0; i < 64; i++) for (int i = 0; i < 64; i++)
if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems
{ {

3
src/types.h
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@@ -348,6 +348,7 @@ const Value QueenValueEndgame = Value(0x9FE);
extern const Value PieceValueMidgame[17]; extern const Value PieceValueMidgame[17];
extern const Value PieceValueEndgame[17]; extern const Value PieceValueEndgame[17];
extern int SquareDistance[64][64];
inline Value piece_value_midgame(Piece p) { inline Value piece_value_midgame(Piece p) {
return PieceValueMidgame[p]; return PieceValueMidgame[p];
@@ -440,7 +441,7 @@ inline int rank_distance(Square s1, Square s2) {
} }
inline int square_distance(Square s1, Square s2) { inline int square_distance(Square s1, Square s2) {
return Max(file_distance(s1, s2), rank_distance(s1, s2)); return SquareDistance[s1][s2];
} }
inline char file_to_char(File f) { inline char file_to_char(File f) {