/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008 Marco Costalba
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
- Glaurung is distributed in the hope that it will be useful,
+ 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
GNU General Public License for more details.
int BAttackIndex[64];
Bitboard BAttacks[0x1480];
-Bitboard SetMaskBB[64];
-Bitboard ClearMaskBB[64];
+Bitboard SetMaskBB[65];
+Bitboard ClearMaskBB[65];
Bitboard StepAttackBB[16][64];
Bitboard RayBB[64][8];
/// pop_1st_bit() finds and clears the least significant nonzero bit in a
/// nonzero bitboard.
-#if defined(USE_32BIT_ATTACKS) && defined(_MSC_VER)
+#if defined(USE_32BIT_ATTACKS)
-// On 32bit system compiled with MSVC this verion seems
-// slightly faster then the standard one.
+// Use type-punning
+union b_union {
-Square pop_1st_bit(Bitboard *b) {
+ Bitboard b;
+ struct {
+ uint32_t l;
+ uint32_t h;
+ };
+};
- unsigned long index;
- uint32_t *l, *h;
+// WARNING: Needs -fno-strict-aliasing compiler option
+Square pop_1st_bit(Bitboard *bb) {
- if (*(l = (uint32_t*)b) != 0)
- {
- _BitScanForward(&index, *l);
- *l &= ~(1 << index);
- }
- else if (*(h = (uint32_t*)b + 1) != 0)
- {
- _BitScanForward(&index, *h);
- *h &= ~(1 << index);
- index += 32;
- } else
- return SQ_NONE;
-
- return Square(index);
+ b_union u;
+ uint32_t b;
+
+ u.b = *bb;
+
+ if (u.l)
+ {
+ b = u.l;
+ *((uint32_t*)bb) = b & (b - 1);
+ b ^= (b - 1);
+ }
+ else
+ {
+ b = u.h;
+ *((uint32_t*)bb+1) = b & (b - 1); // Little endian only?
+ b = ~(b ^ (b - 1));
+ }
+ return Square(BitTable[(b * 0x783a9b23) >> 26]);
}
#else
// be necessary to touch any of them.
void init_masks() {
+ SetMaskBB[SQ_NONE] = 0ULL;
+ ClearMaskBB[SQ_NONE] = ~SetMaskBB[SQ_NONE];
for(Square s = SQ_A1; s <= SQ_H8; s++) {
SetMaskBB[s] = (1ULL << s);
ClearMaskBB[s] = ~SetMaskBB[s];