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Reduce bitboard.cpp

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root 2015-01-10 12:47:14 +00:00
parent 48de70cdb8
commit 1aa5432cb2
1 changed files with 0 additions and 84 deletions
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src/bitboard.cpp
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@ -20,86 +20,6 @@ Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
namespace {
// De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL;
const uint32_t DeBruijn32 = 0x783A9B23;
int MS1BTable[256]; // To implement software msb()
Square BSFTable[SQUARE_NB]; // To implement software bitscan
typedef unsigned (Fn)(Square, Bitboard);
// bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses
// Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch.
inline unsigned bsf_index(Bitboard b) {
b ^= b - 1;
return Is64Bit ? (b * DeBruijn64) >> 58
: ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26;
}
}
#ifndef USE_BSFQ
/// Software fall-back of lsb() and msb() for CPU lacking hardware support
Square lsb(Bitboard b) {
return BSFTable[bsf_index(b)];
}
Square msb(Bitboard b) {
unsigned b32;
int result = 0;
if (b > 0xFFFFFFFF)
{
b >>= 32;
result = 32;
}
b32 = unsigned(b);
if (b32 > 0xFFFF)
{
b32 >>= 16;
result += 16;
}
if (b32 > 0xFF)
{
b32 >>= 8;
result += 8;
}
return Square(result + MS1BTable[b32]);
}
#endif // ifndef USE_BSFQ
/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable
/// to be printed to standard output. Useful for debugging.
const std::string Bitboards::pretty(Bitboard b) {
std::string s = "+---+---+---+---+---+---+---+---+\n";
for (Rank r = RANK_8; r >= RANK_1; --r)
{
for (File f = FILE_A; f <= FILE_H; ++f)
s.append(b & make_square(f, r) ? "| X " : "| ");
s.append("|\n+---+---+---+---+---+---+---+---+\n");
}
return s;
}
/// Bitboards::init() initializes various bitboard tables. It is called at
/// startup and relies on global objects to be already zero-initialized.
@ -108,12 +28,8 @@ void Bitboards::init() {
for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
SquareBB[s] = 1ULL << s;
BSFTable[bsf_index(SquareBB[s])] = s;
}
for (Bitboard b = 1; b < 256; ++b)
MS1BTable[b] = more_than_one(b) ? MS1BTable[b - 1] : lsb(b);
for (File f = FILE_A; f <= FILE_H; ++f)
FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;