return !(b & (b - 1));
}
-
/// first_1() finds the least significant nonzero bit in a nonzero bitboard.
/// pop_1st_bit() finds and clears the least significant nonzero bit in a
/// nonzero bitboard.
#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
FORCE_INLINE Square first_1(Bitboard b) {
- unsigned long index;
- _BitScanForward64(&index, b);
- return (Square) index;
+ unsigned long index;
+ _BitScanForward64(&index, b);
+ return (Square) index;
+}
+
+FORCE_INLINE Square last_1(Bitboard b) {
+ unsigned long index;
+ _BitScanReverse64(&index, b);
+ return (Square) index;
}
#else
__asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
return (Square) dummy;
}
+
+FORCE_INLINE Square last_1(Bitboard b) {
+ Bitboard dummy;
+ __asm__("bsrq %1, %0": "=r"(dummy): "rm"(b) );
+ return (Square) dummy;
+}
#endif
FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
#else // if !defined(USE_BSFQ)
extern Square first_1(Bitboard b);
+extern Square last_1(Bitboard b);
extern Square pop_1st_bit(Bitboard* b);
#endif
+// relative_rank() returns the relative rank of the closest bit set on the Bitboard.
+// Only to be used with bitboards that contain a single file.
+
+template<Color Us>
+inline Rank relative_rank(Bitboard b) {
+ Square s = Us == WHITE ? first_1(b)
+ : ~last_1(b);
+ return rank_of(s);
+}
extern void print_bitboard(Bitboard b);
extern void bitboards_init();