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Skip offset calculation in slider attacks

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Another small simplification and micro optimization.

No functional change in both 32 and 64 bits.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-06-05 14:41:59 +01:00
parent 670cee44f0
commit b1b0c64046
2 changed files with 19 additions and 21 deletions
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19
src/bitboard.cpp
View file

@ -24,9 +24,6 @@
// Global bitboards definitions with static storage duration are
// automatically set to zero before enter main().
Bitboard RAttacks[0x19000];
Bitboard BAttacks[0x1480];
Magics RMagics[64];
Magics BMagics[64];
@ -53,6 +50,15 @@ uint8_t BitCount8Bit[256];
namespace {
CACHE_LINE_ALIGNMENT
int BSFTable[64];
Bitboard RAttacks[0x19000];
Bitboard BAttacks[0x1480];
void init_sliding_attacks(Bitboard attacks[], Magics m[], const Bitboard mult[], Square deltas[]);
#if defined(IS_64BIT)
const uint64_t DeBruijnMagic = 0x218A392CD3D5DBFULL;
@ -163,9 +169,6 @@ const uint64_t RMult[64] = {
#endif // defined(IS_64BIT)
CACHE_LINE_ALIGNMENT int BSFTable[64];
void init_sliding_attacks(Bitboard attacks[], Magics m[], const Bitboard mult[], Square deltas[]);
}
@ -397,7 +400,7 @@ namespace {
{
excluded = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s));
m[s].offset = offset;
m[s].attacks = &attacks[offset];
m[s].mult = mult[s];
m[s].mask = sliding_attacks(s, EmptyBoardBB, deltas, excluded);
m[s].shift = (CpuIs64Bit ? 64 : 32) - count_1s<CNT64>(m[s].mask);
@ -411,7 +414,7 @@ namespace {
index = CpuIs64Bit ? occupancy * mult[s]
: unsigned(occupancy * mult[s] ^ (occupancy >> 32) * (mult[s] >> 32));
attacks[offset + (index >> m[s].shift)] = sliding_attacks(s, occupancy, deltas, EmptyBoardBB);
m[s].attacks[index >> m[s].shift] = sliding_attacks(s, occupancy, deltas, EmptyBoardBB);
}
offset += maxKey;
}

15
src/bitboard.h
View file

@ -69,16 +69,13 @@ extern uint8_t BitCount8Bit[256];
struct Magics {
Bitboard mask;
uint64_t mult;
uint32_t offset;
uint32_t shift;
Bitboard* attacks;
};
extern Magics RMagics[64];
extern Magics BMagics[64];
extern Bitboard RAttacks[0x19000];
extern Bitboard BAttacks[0x1480];
/// Functions for testing whether a given bit is set in a bitboard, and for
/// setting and clearing bits.
@ -176,12 +173,12 @@ inline Bitboard in_front_bb(Color c, Square s) {
inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
const Magics& m = RMagics[s];
return RAttacks[m.offset + (((occ & m.mask) * m.mult) >> m.shift)];
return m.attacks[((occ & m.mask) * m.mult) >> m.shift];
}
inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
const Magics& m = BMagics[s];
return BAttacks[m.offset + (((occ & m.mask) * m.mult) >> m.shift)];
return m.attacks[((occ & m.mask) * m.mult) >> m.shift];
}
#else // if !defined(IS_64BIT)
@ -189,15 +186,13 @@ inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
inline Bitboard rook_attacks_bb(Square s, Bitboard occ) {
const Magics& m = RMagics[s];
Bitboard b = occ & m.mask;
return RAttacks[m.offset +
((unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift)];
return m.attacks[(unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift];
}
inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) {
const Magics& m = BMagics[s];
Bitboard b = occ & m.mask;
return BAttacks[m.offset +
((unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift)];
return m.attacks[(unsigned(b) * unsigned(m.mult) ^ unsigned(b >> 32) * unsigned(m.mult >> 32)) >> m.shift];
}
#endif