#if defined(IS_64BIT)
+static const uint64_t DeBruijnMagic = 0x218A392CD3D5DBFULL;
+
const uint64_t BMult[64] = {
0x0440049104032280ULL, 0x1021023C82008040ULL, 0x0404040082000048ULL,
0x48C4440084048090ULL, 0x2801104026490000ULL, 0x4100880442040800ULL,
#else // if !defined(IS_64BIT)
+static const uint32_t DeBruijnMagic = 0x783A9B23;
+
const uint64_t BMult[64] = {
0x54142844C6A22981ULL, 0x710358A6EA25C19EULL, 0x704F746D63A4A8DCULL,
0xBFED1A0B80F838C5ULL, 0x90561D5631E62110ULL, 0x2804260376E60944ULL,
namespace {
+ CACHE_LINE_ALIGNMENT int BSFTable[64];
+
void init_masks();
void init_step_attacks();
void init_pseudo_attacks();
#if defined(IS_64BIT) && !defined(USE_BSFQ)
-static CACHE_LINE_ALIGNMENT
-const int BitTable[64] = {
- 0, 1, 2, 7, 3, 13, 8, 19, 4, 25, 14, 28, 9, 34, 20, 40, 5, 17, 26,
- 38, 15, 46, 29, 48, 10, 31, 35, 54, 21, 50, 41, 57, 63, 6, 12, 18, 24, 27,
- 33, 39, 16, 37, 45, 47, 30, 53, 49, 56, 62, 11, 23, 32, 36, 44, 52, 55, 61,
- 22, 43, 51, 60, 42, 59, 58
-};
-
Square first_1(Bitboard b) {
- return Square(BitTable[((b & -b) * 0x218a392cd3d5dbfULL) >> 58]);
+ return Square(BSFTable[((b & -b) * DeBruijnMagic) >> 58]);
}
Square pop_1st_bit(Bitboard* b) {
Bitboard bb = *b;
*b &= (*b - 1);
- return Square(BitTable[((bb & -bb) * 0x218a392cd3d5dbfULL) >> 58]);
+ return Square(BSFTable[((bb & -bb) * DeBruijnMagic) >> 58]);
}
#elif !defined(USE_BSFQ)
-static CACHE_LINE_ALIGNMENT
-const int BitTable[64] = {
- 63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2,
- 51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5,
- 52, 26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38,
- 28, 58, 20, 37, 17, 36, 8
-};
-
Square first_1(Bitboard b) {
-
b ^= (b - 1);
- uint32_t fold = int(b) ^ int(b >> 32);
- return Square(BitTable[(fold * 0x783a9b23) >> 26]);
+ uint32_t fold = unsigned(b) ^ unsigned(b >> 32);
+ return Square(BSFTable[(fold * DeBruijnMagic) >> 26]);
}
// Use type-punning
if (u.dw.l)
{
- ret = Square(BitTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783a9b23) >> 26]);
+ ret = Square(BSFTable[((u.dw.l ^ (u.dw.l - 1)) * DeBruijnMagic) >> 26]);
u.dw.l &= (u.dw.l - 1);
*bb = u.b;
return ret;
}
- ret = Square(BitTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783a9b23) >> 26]);
+ ret = Square(BSFTable[((~(u.dw.h ^ (u.dw.h - 1))) * DeBruijnMagic) >> 26]);
u.dw.h &= (u.dw.h - 1);
*bb = u.b;
return ret;
for (Bitboard b = 0; b < 256; b++)
BitCount8Bit[b] = (uint8_t)count_1s<CNT32>(b);
+
+ for (int i = 1; i < 64; i++)
+ if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems
+ {
+ Bitboard b = 1ULL << i;
+ b ^= b - 1;
+ b ^= b >> 32;
+ BSFTable[uint32_t(b * DeBruijnMagic) >> 26] = i;
+ }
+ else
+ BSFTable[((1ULL << i) * DeBruijnMagic) >> 58] = i;
}
void init_step_attacks() {